chapters 1 to 9
TRANSCRIPT
i
TABLE OF CONTENTS
Chapter 1: INTRODUCTION 1
1.1. Importance of electric usage in new human's life
1.2. History of electric industry and its expansion
1.3. Distribution system planning
1.4. Factors affecting planning system
1.5. Objective of the projects
1.6. Summary
Chapter 2: BUILDING WIRING CALUCLATION 4
2.1. Introduction
2.2. General Overview on Light 2.2.1. Nature of light
2.2.2. Basic Definitions
2.2.3. Requirements of a good lighting scheme
2.2.4. Factors affecting the illumination and wattage of a certain lamp
2.3. Types of lighting schemes
2.3.1. Direct Lighting
2.3.2. Semi-direct Lighting
2.3.3. Indirect lighting
2.3.4. Semi-indirect lighting
2.3.5. General lighting
2.4. Artificial sources of light 2.4.1. Arc lamps
2.4.2. Incandescent electric lamps
2.4.3. Discharge lamps
2.5. Building wiring calculations 2.5.1. Lighting loads calculations
2.5.2. Socket Loads
2.5.3. Riser calculations
2.6. General points to be considered in the design
2.7. Calculation of loads for flats & villas 2.7.1. Flat type (A)
2.7.2. Flat type (B)
2.7.3. Flat type (C)
2.7.4. Flat type (D)
2.7.5. Flat type (E)
2.7.6. Villa type (a)
2.7.7. Villa type (b)
2.7.8. Villa type (C)
ii
Chapter 3: LOW VOLATGE DISTUBUTION NETWORK PLANNING 84
3.1. Introduction
3.2. General Overview on the distribution system 3.2.1. Distribution Transformer
3.2.2. Distribution Box (Pillar)
3.2.3. Building Box (Coffree)
3.3. Low Voltage Network (LVN) types 3.3.1. Radial LVN
3.3.2. Open Loop (Ring) LVN
3.4. General points to be considered in design
3.5. Planning of Distribution Network in the Residential Area 3.5.1. Calculation of Distribution Boxes (Pillars) and Feeders ratings
3.5.2. Calculation of Transformer and feeders ratings
3.5.3. Voltage drop Calculations
3.5.4. Short Circuit Current Calculations
3.6. Example of calculations
Chapter 4: MEDIUM VOLTAGE DISTRIBUTION NETWORK 103
4.1. Introduction
4.2. General Overview on Medium Voltage Network (Primary Distribution Network)
4.3. Medium Voltage Network Types 4.3.1. Medium voltage switchboard supply modes
4.3.2. Medium voltage network structure
4.4. Calculation of the distribution point and sizing of the 22 KV cables
Chapter 5: 66/22 KV SUBSTATION 120
5.1. Introduction
5.2. General Overview
5.3. Substation Classifications
5.4. Types of substation
5.5. Substation layout
5.6. Substation Equipment
5.7. Earthing and Bonding
5.8. Essential Civil Structure in outdoor substations
5.9. Description of the Single Line Diagram and Layout for the Present 66/22KV
Substation
iii
Chapter 6: POWER SYSTEM PROTECTION 134
6.1. Introduction
6.2. General Overview
6.3. Types of faults in power systems
6.4. Division of power systems into protective zones
6.5. Fuses
6.6. Basic elements of protective switchgear
6.7. Relay
6.8. Differential Protection of Power systems
6.9. Applications:
6.10. Circuit Breakers
Chapter 7: STREET LIGHTING 158
7.1. Introduction
7.2. Classification of factors affecting the design of street lighting
7.3. Street lighting arrangements
7.4. Street lighting design process
7.5. Types of lamps used in Street lighting
7.6. Methods of switching of lamps
7.7. Street lighting system
7.8. Lighting control and Wiring system
7.9. Design of the street lighting scheme using DIALux program
Chapter 8: SYSTEM GROUNDING 171
8.1. The importance of Earthing
8.2. Types of earthing
8.3. Safety or protective
8.2. Types of earthing
8.4. System Earthing
8.5. Methods of Earting
8.6. Circuits & equations
8.7. Earth Resistivity & Gradient
8.8. Earth electrodes &networks
8.9. measurement of earth electrode resistance & earth loop impedance
8.11. The high pulse voltage E.S.E. lightening conductor
8.10. Substation earthing
iv
Chapter 9: The Shopping Mall 181 9.1. Introduction
9.2. Ground Floor 9.2.1. Ground Floor Lighting Calculations
9.2.2. Ground Floor Socket Calculations & Wiring
9.2.3. Ground Floor Local Feeders
9.2.4. Ground Floor SMDBs & Cable Tray Dimension
9.2.5. Ground Floor Emergency Backup Scheme
9.3 First Floor 9.3.1. First Floor Lighting Calculations
9.3.2. First Floor Socket Calculations & Wiring
9.3.3. First Floor Local Feeders
9.3.4. First Floor SMDBs & Cable Tray Dimension
9.3.5. First Floor Emergency Backup Scheme
9.4. Second Floor 9.4.1. Second Floor Lighting Calculations
9.4.2. Second Floor Socket Calculations & Wiring
9.4.3. Second Floor Local Feeders
9.4.4. Second Floor SMDBs & Cable Tray Dimension
9.4.5. Second Floor Emergency Backup Scheme
9.5. Air Conditioner and Elevator Panel (Roof Panel)
9.6. Mall Panel Boards Connection Diagram & Cable Specifications 9.7.2. Electrical Rooms 2 Panel Boards
9.7. Detailed Single Line Diagram of Each Panel Board 9.7.1. Electrical Rooms 1 Panel Boards
9.7.2. Electrical Rooms 2 Panel Boards
9.7.3. Emergency Panel Boards
9.8. Emergency Operation 9.8.1. ATS specifications
9.8.2. Emergency Generator
Chapter 10 223
Appendices
References
Introduction
Chapter 1
CHAPTER 1 INTRODUCTION
1
Chapter 1
INTRODUCTION
1.1 Importance of electric usage in new human's life:
As long as the electricity is available, no one thinks much about it. The importance
is realized when the power goes out. Whether itโs during the day or at night,
electricity keeps our lives in order. It affects your business, your schedule and even
your entertainment.
Electricity runs everything in our everyday life. Gas stations canโt pump gas
without it. Businesses have to close because their cash registers wonโt work without
it. Restaurants canโt cook food without it. Our lives almost come to a standstill
without electricity.
These are the times when back up electricity is most needed and becomes very
important. It can keep our clocks running, so we arenโt late for work. Appointments
will be kept on time. Itโs important to keep on schedule and backup electricity can do
just that.
1.2 History of electric industry and its expansion
The electric utility industry was born in 1882 when the 1st electric power station in
New York City went into operation .The industry grew up rapidly & generation
stations & transmission & distribution networks have spread across the entire
country., Energy is expected to be increasingly converted to electricity after year
2000. In the past the distribution systems represented over 80 percent of total system
investment .Production expenses is the major factor in the total electrical operation &
maintenance.
1.3 Distribution system planning
System planning is essential to assure that the growing demand for electricity can
be satisfied by both technically adequate & reasonably economical.
It is application has unfortunately been somewhat neglected. In the future, electric
utilities will need a fast & economical planning to provide the necessary economical,
reliable, and safe electric energy to consumers can be satisfied in an optimum way by
additional distribution systems, from the secondary conductors through the bulk
power substations. The distribution system's particularly important to an electrical utility for two
reasons:
It's close proximity to the ultimate customer. 1-
2-It's high investment cost.
CHAPTER 1 INTRODUCTION
2
1.4 Factors affecting planning system The number & complexity affecting system planning appears initially to be
staggering. The planning problem is an attempt to minimize the cost of sub-
transmission, sub-stations, feeders, as well as losses cost.
A) Load forecasting. The load growth of the geographical area served by a utility company is the
most important factor as it's essential to the planning process.
There are 2 common time scales:
*Long range (with time horizons on the order of 15~20 years old).
*Short range (with time horizons on the order of 5 years old).
B) Substation expansion. The planner makes a decision based on tangible or in tangible information. For ex.,
the forecasted load, load density, & load growth may require a substation or a new
substation construction .Here capacity & forecasted loads can play major roles.
C) Substation site selection. The distance from the load centers & from the existing sub-transmission lines as
well as other limitations such as availability of land, its cost, & land use regulations
are important.
The s/s sitting process can be described as a screening procedure through which all
possible locations for a site are passed .The service region is the area under
evaluation.
D) Other factors.
1.5 Objective of the projects Our target in this project is to study the factors affecting the Planning and
Distribution of a Power System in some specified areas; Agriculture, Residential, City
Center, Industrial.
At first, weโll begin by forecasting of loads in these areas for the next 10 years
(approximately) depending on a well known data of the previous years, so we are able
to calculate the load densities in these areas as follows:
Around 4~5 persons for each flat according to the living life level.
This table shows the different areas and the number of its people:
Zone Zone Area(mยฒ) Unit Area(m2) Class Population(persons)
Green 58100 205 High 1440 Cyan 130000 110 Low 9696
Pink 213600 138 Medium 13920
Orange 134500 245 Very High 3420
Yellow 88500
145 Medium 2800
40200 1840
Red 85600 300 Very High 390 Blue 120000 200 High 1440
White 51800 200 High 345
Total area of layout =1,260,000m
2
Total population =35,291 persons
CHAPTER 1 INTRODUCTION
3
After studying the load forecast, and calculating the load densities in the areas
mentioned before,
In chapter 2, weโll begin to discuss the adequate building wiring techniques, and
make their calculations, as to say, weโll begin to distribute electricity in building,
beginning by lighting and sockets loads inside flats, and reaching the riser
calculations and coffree of each building type, so we are able to choose the suitable
cables used in building wiring.
Then, weโll study the low voltage network and the distribution of the electric power
from medium voltage transformers to the distribution boxes and to the coffrees of
buildings, and thus calculating the suitable cables used in this part of the power
system network, and this is mentioned in chapter 3.
After studying the low voltage network, itโs desired to study the medium voltage
network that supplies this low voltage network, and this is discussed briefly using
some illustrated diagrams in chapter 4.
In chapter 5, weโll begin to talk about the design, construction and performance of
the high voltage distribution substations, and weโll mention the layout of the 66/22
KV substation.
Then weโll discuss the protection schemes of each part of the power system
showing which equipments are used in protection and their constructions, as well as
their theory of operation, and this will be in chapter 6.
Also weโll talk about the switchgear and its main components, and the different
types of circuit breaker, discussing the theory of operation and principles of
interrupting the arc in each type.
In chapter 7, weโll have an overview on the street lighting, the types of roads, the
different types of lamps used in the illumination of each type of roads, and the
wattage available of street lighting lamps.
In chapter 8, weโll have an overview on system grounding, its different schemes
and methods of grounding to the different components and equipments of our system.
After reaching that point, we have described the main steps in planning and
distribution of power system in a developed area, but before ending our project, weโll
add an additional project talking about the distribution of lighting and socket loads in
a mall. And that will be in chapter 9.
1.6 Summary In planning of a distribution system, we have to take many factors into
consideration. The most important factors are trying to make the system technically
good and reliable, not forgetting to consider the economic point of view.
BUILDING WIRING CALUCLATION
Chapter 2
CHAPTER 2 BUILDING WIRING CALCULATION
4
Chapter 2
BUILDING WIRING CALUCLATION
2.1 Introduction
Light is the prime factor in the human life as all activities of human beings
ultimately depend upon the light. Where there is no natural light, use of artificial is
made. Lighting increases production, reduces fatigue, protecting the health, eyes and
nervous system, and reduces accidents.
In this chapter, we are concerned with studying the electric indoor wiring design
including the lighting design, normal sockets and power sockets design. We are also
concerned with riser calculations and design of the suitable riser required in every
kind of buildings.
The mains wiring is generally built using insulated copper cables. The choice of
conductor material is a compromise among electrical properties, mechanical
properties, and price. From the start, copper has been the material of choice for
household branch circuits.
Aluminum is softer than copper and weaker, and a poorer electrical conductor, so is
not widely used in small sizes for home wiring. Aluminum cable material is
sometimes used (for economical reasons) for thick mains feeder cables coming from
electrical utility to the mains distribution panel.
The ratings of the sub-circuits' miniature circuit breakers (M.C.B) and the main
circuit breaker of the flat or the villa as well as energy meter are selected.
Any house that has been properly wired will have a circuit breaker panel used to
shut circuits off in case they draw too much current. It is the current capacity of
circuit breaker (in amperes) that determines how much current a circuit can supply. In
case of an overload or a short-circuit on that circuit, the breaker trips and
automatically shuts off power to that circuit. Ground fault circuit breakers offer
protection against more than just overloads.
After the load of the flat is being calculated, the diversified estimation of the total
load of the building is made. The buildings are fed from distribution boxes via cables
of suitable sizes, forming a part of the low voltage distribution network. The
distribution boxes are fed from 22 KV/380 V distribution transformers, preferably in
loops, to secure the continuity of supply to the distribution boxes and hence to the
buildings.
Detailed calculations and planning of the 380V low voltage distribution network, the
22KV medium voltage network as well as details of the 66/22KV substation feeding
the area, are presented in the following chapters. Before this, the principles of lighting
and wring are summarized in the following sections.
CHAPTER 2 BUILDING WIRING CALCULATION
5
2.2 General Overview on Light
2.2.1 Nature of light:
Various forms of incandescent bodies are sources of light and their light is emitted
by such bodies depending upon their temperature. Energy is radiated into the medium
by a body which is hotter than the medium surrounding it, in the form of
electromagnetic waves of various wavelengths. The velocity of propagation of radiant
energy is approximately 8103 m/sec. The properties and behavior of the radiant
energy depends upon the wavelength. When the temperature is low, the wavelength of
radiant energy will be sufficiently large and the available energy is in the form of heat
waves. As the temperature increases, the wavelength of the radiated energy becomes
smaller and smaller and enter into the range of the wavelength of the light. The
wavelength which can produce the sensation varies from 0.0004 to 0.00075 cm. the
wavelength of the light is expressed in Angstrom unit.
Where 1 Angstrom unit (A.U.) = 810cm.
2.2.2 Basic Definitions
Candela
International unit (SI) of luminous intensity; term evolved from considering a
standard candle, similar to a plumber's candle, as the basis of evaluating the
intensity of other light describe the relative intensity of a source .
Candlepower Distribution Curve
A graphical representation of the distribution of light intensity of a lamp or
luminaire.
Illumination (E)
The quantity of light (measured in foot-candles, Lux, etc) at a point on a
surface.
Inverse Square Law
Formula stating that illumination at a point on a surface varies directly with
the intensity of a point source, and inversely as the square of the distance between
the source and the point; it illustrates how the same quantity of light flux is
distributed over a greater area as the distance from the source to the surface is
increased.
Light Loss Factor
The product of all considered factors that contribute to a lighting system's
depreciated light output over a period of time, including dirt and lamp lumen
depreciation.
Lumen
The international unit of luminous flux or quantity of light.
CHAPTER 2 BUILDING WIRING CALCULATION
6
Luminaries
A complete lighting unit consisting of a lamp (or lamps) together with the
parts designed to distribute the light position and protect the lamps, and connect
them to the power supply. This is sometimes referred to as a "fixture".
Lamp efficiency
It is the amount of output lumen per watt.
Lux (lumen/mยฒ)
SI (international system) unit of illumination. One lumen uniformly distributed
over an area of one square meter.
Mounting Height
Distance from the bottom of the fixture to either the floor or work plane,
depending on usage.
Spacing to Mounting Height Ratio
Ratio of fixture spacing (distance apart) to mounting height above the work
plane. Sometimes it is called spacing criterion. A normal range is 1 1.5.
2.2.3 Requirements of a good lighting scheme:
A good lighting scheme should fulfill the following:
1. Provide adequate illumination.
2. Provide uniform illumination all over the working plan.
3. Provide light of suitable color.
4. Avoid glare and hard shadows.
2.2.4 Factors affecting the illumination and wattage of a certain lamp:
Utilization factor (U.F): (0.2 0.6)
It is the ratio of the lumen actually received to the total Lumens emitted by the
source, it depends on:
a. Room dimensions.
b. Color of the walls.
c. Type of lighting scheme.
Maintenance factor (M.F):
It is the ratio between illuminations under normal working conditions to the
illumination when everything is clean. It depends on the rate of cleaning.
M.F = 0.8 for houses.
= 0.3 for streets.
= 0.6 0.7 for schools and shopping centers.
Waste factor:
The ratio between the resultant illuminations due to more than one luminaire to
the summation of their illumination when they work individually. Waste factor is
CHAPTER 2 BUILDING WIRING CALCULATION
7
less than unity due to the loss when a place is illuminated by more than one source
due to overlapping.
Reflection factor:
Due to the fact that light reflected by an angle of incidence when impinged on a
surface.
Room index (k):
It is a factor that depends on the dimension of the room. It equals the ratio
between the product of length (L) and breadth (W) of the room to the product of
the mounting height (H) and the summation of the length and breadth of that room.
K = )(*
*
WLH
WL
Generally K varies from 0.6 to 5.0
2.3 Types of lighting schemes
Lighting schemes maybe classified as:
2.3.1 Direct Lighting
Itโs the most commonly used type of lighting schemes. In this type of lighting, the
light from the source falls directly on the object or the surface to be illuminated. In
this lighting scheme, more than 90 % of total light flux is made to fall directly on the
working plane with the help of reflectors, shades and globes. Itโs important to keep
lamps and fittings clean, otherwise the decrease in effective illumination due to dirty
bulbs or reflectors maybe amount to 15-25 % in offices and domestic lighting and
more in industrial areas.
Although direct lighting is most efficient but it causes hard shadows and glare.
Itโs mainly used for industrial and general outdoor lighting.
2.3.2 Semi-direct Lighting
This system utilities luminaries which send most of the light downwards directly
on the working plane but a considerable amount reaches the ceiling and walls. The
deviation is usually 70 % downwards and 30 % upwards.
Such systems are best suited to rooms with high ceilings where high levels of
uniformly distributed illumination desirable. Glare is avoided by using diffusing
globes which improve the brightness of the working plane.
2.3.3 Indirect lighting
In this form of lighting, light doesnโt reach the surface directly from the source,
but indirectly by diffuse reflection. Lamps are either placed behind a cornice or in
suspended opaque bowels. The division is usually 10 % downwards and 90 %
upwards.
CHAPTER 2 BUILDING WIRING CALCULATION
8
One of the main characteristics of indirect lighting is that it provides shadow-less
illumination which is very useful for drawing offices, composing rooms, and in
workshops. Itโs also used for decoration purposes in cinemas, hotels and theaters.
2.3.4 Semi-indirect lighting
In this system, the light partly received by diffuse reflection and partly direct from
the source. Most of light is directed upwards to the ceilings for diffuse reflection and
the rest reaches the working plane. The division is usually 25 % downwards and 75 %
upwards.
Itโs mainly used for indoor lighting decoration purpose.
2.3.5 General lighting
In this system, such illumination are employed which have almost equal light
distribution downwards and upwards.
2.4 Artificial sources of light
The various methods of producing light by electricity are:
1. By arc: By establishing an arc between carbon electrodes.
2. Incandescence of heated filament:
Where an electric current is passed through a filament of thin wire placed in
vacuum or an inert gas. The current generates enough heat to raise the temperature of
filament to luminosity.
3. Glow discharge:
Operate by ionization of gas. The color and intensity of light emitted depend
on the nature of the gas or vapor.
2.4.1 Arc lamps
The various forms of arc lamps are:
a) Carbon arc lamps
b) Flame arc lamps
c) Magnetic arc lamps
2.4.1. a Carbon arc lamps
Two hard carbon rods are placed and connected to a D.C. supply of not less
than 45 volts.
The source of light is incandescent electrode.
The arc is maintained by the transfer of carbon particles from one rod to the
other rod.
White light is produced.
A series resistance is used in stabilizing the arc.
The luminous efficiency of the lamp is 12 lumens / watt.
Used in cinemas projectors.
CHAPTER 2 BUILDING WIRING CALCULATION
9
2.4.1.b Flame arc lamps
The principle of operation is similar to that of carbon arc lamps.
It consists of carbon electrodes which are cored and filled with 5-15 % flame
material (fluoride) and 85-95 % carbon.
Different flame materials produce different colors.
The colors produce strain on eyes and do not appeal to eyes. Therefore, they
are replaced by discharge lamps.
The luminous efficiency of such lamp is 8 lumens / watt.
2.4.1.c Magnetic arc lamps
Such lamp has positive electrode made of copper and negative electrode made
of magnetic oxide of iron.
Itโs rarely used.
The arc is struck in similar ways as in case of carbon lamp.
2.4.2 Incandescent electric lamps
It consists of a fine wire of a high resistance metal placed in a glass bulb and
heated to luminosity by passage of current through it.
At low temperature, the wire radiates heat energy due to heating; it radiates heat
as well as light energy.
The higher the temperature of the wire results in a higher light energy radiated.
Properties of ideal material for filament lamps
High melting temperature
Low vapour pressure
Higher specific resistance
Low temperature coefficient
There are two types of incandescent lamps
a) Vacuum lamps
b) Gas filled lamps
2.4.2.a Vacuum lamps
Consists of a glass globe completely evacuated and a fine filament in it.
The purpose of vacuum is to prevent loss of heat from filament to bulb. And
also to prevent oxidation of the filament.
The highest temperature in a vacuum lamp is limited to 2100 ยฐC.
2.4.2.b Gas filled lamps
A metal filament can work in an evacuated bulb up to 2000 ยฐC without
oxidation.
To get higher efficiency, itโs necessary to raise the temperature more than
2000 ยฐC. This can be achieved by filling the bulb with an inert gas (argon)
with a small amount of nitrogen to reduce the possibility of arcing.
Introduction of inert gases enables the temperature to rise to about 2500 ยฐC.
Itโs used for flood lights of buildings, projectors and motor car headlights.
CHAPTER 2 BUILDING WIRING CALCULATION
10
Important characteristics of incandescent lamps
o They are very inefficient producers of light as less than 10 % of the wattage
goes to produce light, while the remainder is heat.
o Principle advantage is the low cost.
o It starts instantly.
o It has a cheap dimming.
o It has a good warm color.
2.4.3 Discharge lamps
They are superior to metal filament lamps.
Light is obtained by applying an electric potential difference, gas gets ionized and
an electric current flows and the tube is filled with luminous discharge.
The color is obtained and depends upon the nature of the gas or vapour used.
There are two types of discharge lamps:
1) Those which give light of the same colour as produced by the discharge
2.4.3.a Sodium vapor lamps
Consists of a bulb containing a small amount of metallic sodium neon gas and
two sets of electrodes connected to a pin type base.
The major application is for high ways and general outdoor lighting.
Its ratings are 45, 60, 85 and 140 watts and have average life time of about
3000 hours.
There are two types of sodium vapor lamps which are:
- High pressure sodium vapor lamps
- Low pressure sodium vapor lamps
2.4.3.b High pressure mercury vapor lamps
It consists of two bulbs, an arc tube containing the electric discharge and
houses three electrodes.
There are two main electrodes and an auxiliary starting electrode.
When supply is switched, an initial discharge is established in argon gas
between one of the main electrodes and the auxiliary electrode and then in
argon between the two main electrodes.
The produced heat is sufficient to evaporate mercury; the operation takes
about 5-7 minutes.
Emitted light is greenish-blue light and true reddish is not possible as there is
complete absence of red light from radiations and red objects appear black.
Its efficiency is about 40 lumens / watt, and lamps are produced in 250 and
400 watt for use on 200-250 a.c. voltage supplies.
Applications of mercury vapor lamps
Street lighting.
Industrial lighting where high illumination level is required and reddish light
is not important.
CHAPTER 2 BUILDING WIRING CALCULATION
11
2.4.3.c Neon lamps
It belongs to the cold cathode lamps.
It consists of a glass bulb filled with neon gas with small amount of helium.
It gives orange-pink colored light.
If helium gas is used in place of neon, white pink light is obtained.
Electrodes are of pure iron and placed few millimeters apart.
High resistance is used to prevent arcing.
Its efficiency is 15 lumens / watt.
Applications of neon lamps:
Itโs used as indicator lamps.
Itโs used in advertising.
2) Those which use the phenomena of fluorescence and are known as fluorescent
lamps.
2.4.3.d Fluorescent lamps
It consists of a long glass tube internally coated with fluorescent powder.
The glass tube contains a mixture of inert gas (argon) and mercury vapour.
A choke coil is in the circuit to limit current and provide a voltage impulse for
starting.
The lamp has starter which acts as a switch.
The efficiency of the lamp is about 40 lumens / watt and it has an average life
time of about 4000 hours.
Advantages of fluorescent lamps:
Efficiency is much higher than incandescent lamps.
It produces less heat radiations.
Itโs of relatively large size and low surface brightness.
2.4.3.e Compact Fluorescent Lamps (CFL)
It is a new and advanced lighting technology
More efficient than incandescent lamps
CFL use 70 - 75% less energy than their incandescent equivalents. When
replacing a 100 watt incandescent lamp a 28 watt CFL is used.
CFL last approximately 10,000 hours, which is 10 to 13 times the life of an
incandescent lamp (expected life approximately 750 hours).
Compact fluorescents are most cost-effective when used at least 2-3 hours per
day.
Although CFL may appear different than the common incandescent, they fit
most standard fixtures found in homes today. The screw-in base is the same on
both lamps.
The typical incandescent lamp wastes 90% of the energy it uses, producing
heat rather than light.
CFL will provide the same amount of light (or lumens) at a fraction of the
electricity used.
CHAPTER 2 BUILDING WIRING CALCULATION
12
2.5 Building wiring calculations
2.5.1 Lighting loads calculations
a) Lux's:
Type Lux
Stairs 50
Saloon 150
Bedrooms 120
Kitchen 300
Bathroom 300
b) Determine room factor (Ri) from tables according to the room dimensions.
Example: kitchen (4.7m*3.6m*2.7m). Ri=G type.
c) Determine utilization factor (u) for the type you choose from tables.
Example: kitchen (uแต) ceiling=75%, wall=50%. uแต=0.41.
d) Choose maintenance factor (m).
For regular maintenance: (0.76 to 1).
For irregular maintenance: (0.66 to 0.75)
e) Using : ๐ =๐ธโ๐ด
๐ขโ๐โ๐โ๐
Where:
N=number of lamps.
E=needed Lux.
A=room area.
U=utilization factor.
ฮท= Lamp efficiency (lumen/watt).
For incandescent lamp:
Rating: 25, 40, 50 , 60 , 80 , 100 ,120,200 Watt.
Power factor = 1.
ฮท=80 lumen/watt.
For fluorescent lamp:
Rating: 20, 40 Watt.
Power factor = 0.8.
ฮท=20 lumen/watt.
CHAPTER 2 BUILDING WIRING CALCULATION
13
2.5.2 Socket Loads
4.5.2.a Normal sockets (N.S.)
They have different ratings, which can be used such as 2A, 5A,10A the ratings of
2A,5A, can be used for bedrooms, entrance, balcony, which requires low electrical
sets as T.V, radio and small electric fans...etc.
In general we are going to use only the 2A sockets in all the rooms since this is
more practical.
4.5.2.b Power sockets (P.S.)
Sometimes we need some sockets to be used for special purposes like: full
automatic washing cloth machines, air conditions, water heaters, dish washers,
electric ovens and toasters. Such sockets are called power sockets and they require
higher current rating and taking into consideration the starting period which increases
the delivered current to a value higher than normal operation.
To estimate the socket load for certain domestic units the following are to be
considered:
a) Generally there are 2-5 sockets in the room.
b) Generally there are 5-8 normal sockets on a line.
c) Referring to the IEC standard specification, the ratings of sockets are:
M.C.B. rating for normal socket = 10 A
M.C.B. rating for power sockets = 16 A. or 25 A.
d) Calculate the normal socket loads on a line is according to the formula:
Socket load on a line = 100% of largest normal socket rating on the line +
(20%) of ratings of other normal sockets.
e) Each power socket has its own line.
f) To make calculations more exact, we should expect the loads to be used and
their power like:
Radio cassette : 40w, 0.182 A
T.V set: 65 w, 0.3 A
Video: 30w, 0.137 A
Vacuum cleaner: 800w, a p.f of 0.85 , 4.7 A
fans :200w, a p.f of 0.85, 1.069 A
Shaving Machine: 150w, 0.7 A
Hair dryer: 600w, a p.f of 0.85, 3.2 A
Small fridge to be placed in the bedroom: 80w, a p.f of 0.85, 0.43 A
Fridge :160w, p.f of 0.85, 0.86 A
Kitchen machine :600w, p.f of 0.85, 3.2 A
Water Heater:1500w, 6.82 A
Normal washing machines: 1500w, p.f of 0.9, 7.57 A.
Iron: 1000w, 4.64 A.
Sound system: 800w, 3.64 A
Air Conditioner: 2.25 Hp, p.f. 0.9,8.477 A
CHAPTER 2 BUILDING WIRING CALCULATION
14
2.5.3 Riser calculations
The riser is cable, which passes upward in each building for transmitting the
electric power from the coffree of the building to each unit of this building, in other
words, it starts from the fuse at the bottom of the house to the highest flat.
It is a three phase cable made usually of copper and has a number of outputs
equals to the number of floors; the output of riser is connected to the fuses which
feeds this floor.
Riser may be one cable or double cable depending on the height of the house, the
number of flats and on the load of each flat.
When choosing the riser we follow the next steps:
a) Calculating the KVA of the flat before diversification and use to determine the
suitable diversification curve.
b) We have two methods to get the diversified KVA of the flat:
i. Using the total number of flats in the building to get the diversified KVA
of the flat. Multiply this diversified KVA by the number of flats in the
building to get the total KVA of the building. Dividing this KVA by
380 3 we get the current that flows in the riser.
ii. Using the total number of flats on each phase to get the diversified KVA of
the flat. Multiply this diversified KVA by the number of flats on the phase
to get the total KVA per phase. Dividing this KVA by 220 we get the
current that flows in the riser.
c) Assuming that the riser must never be loaded by more than 80% of its current
capacity, we can get the current capacity of the riser by dividing the current
obtained in the last step by 0.8.
d) By knowing the value of the current capacity and using the tables of cables
attached in the appendix we can get the c.s.a of the riser and also the rating of
the fuse used for protection. In general 3-ph risers that are used are of the
following sizes: 10 mmยฒ, 16mmยฒ, 25mmยฒ, 50mmยฒ and 70mmยฒ.
e) Other services loads like water pumps, elevators (for buildings more than 6
floors) and stairs lighting are to be considered in our calculations.
f) A fuse is added for protection.
2.6 General points to be considered in the design:
1. In distribution of loads among light circuits or socket circuits we should
connect the rooms that are next to each other on the same sub circuit to avoid
crossing between connections. Also it is recommended that the circuits of the
same type are equally loaded.
2. Diversity factor between the sockets on the same line depends on some factors
like the area of the flat, the larger the area the smaller the diversity factor used.
3. In calculating the required amount of light for the shaving mirror in the
bathroom we consider the recommended lux to be half of that required for the
bathroom yet the area is the same area of the bathroom. We use incandescent
lamps for the shaving mirror.
4. Flats of area less than 90 mยฒ are considered as youth housing thus single phase
energy meters are used in them.
CHAPTER 2 BUILDING WIRING CALCULATION
15
5. The distribution of flats among riser phases is done in a way to make voltage
drop on each phase exactly equal to other phases.
6. Single phase energy meters are of ratings 20A and 40A. Three phase energy
meters are 3ร20A, 3ร25A, 3ร40A and 3ร80A.
7. For the c.s.a of the neutral conductor, we follow the Egyptian Electric Code
(EEC) which states " If the c.s.a of the phase conductor is less than or equal 16
mmยฒthen the neutral conductor is of the same c.s.a as the phase conductor. If
the phase conductor is of c.s.a less than 35 mmยฒthen the neutral conductor is of
c.s.a equal to the one preceding the concerned phase conductor. If the c.s.a of
the phase conductor is more than or equal 50 mmยฒ then the c.s.a of the neutral
conductor is half of the concerned phase conductor.
8. In general all our distribution of loads among the lines or the phases we must
care that the loads are almost balanced as much as we can to avoid the
unbalanced operation.
9. Low voltage fuses ratings are as follows:
2, 4, 6, 8, 10, 16, 20, 25, 32, 35, 40, 50, 63, 80, 100,125 and 160 according to
ABB pocket book (switchgear manual), 8th edition.
2.7 Calculation of loads for flats & villas:
2.7.1 Flat type (A)
a) Lighting:
Line room length width Lux Area u ฦ number of lamps lamps lamps wattage power factor
installed wattage
lamp current line 1 line2 line3 line4
1 Entrance 3.55 1.7 50 6.035 0.49 20 0.384885204 1 100 1 100 0.454545455 0.454545
1 Entrance Hall 1.7 4.35 50 7.395 0.49 20 0.786033163 2 60 1 120 0.545454545 0.545455
4 Inner Hall 5.5 2.5 50 13.75 0.49 20 1.461522109 2 60 1 120 0.545454545
0.545455
2 Saloon 4.8 11.95 150 57.36 0.49 20 18.29081633 20 60 1 1200 5.454545455 2.75 2.75
2 Balcony 1 3.25 5.8 50 18.85 0.49 20 1.202168367 2 100 1 200 0.909090909
0.909091
3 Bedroom 1 4 4.4 120 17.6 0.49 20 4.489795918 6 60 1 360 1.636363636
1.636364
3 Balcony 4 1.5 1.5 50 2.25 0.49 20 0.239158163 1 60 1 60 0.272727273
0.272727
3 Bathroom 2 2.3 2.1 300 4.83 0.35 80 1.6171875 2 40 0.8 80 0.454545455
0.454545
4 Kitchen 4.7 3.7 300 17.39 0.41 80 4.970464939 6 40 0.8 240 1.363636364
1.363636
4 Balcony 3 3 1.15 50 3.45 0.49 20 0.366709184 1 60 1 60 0.272727273
0.272727
4 Bathroom 1 1.45 3 300 4.35 0.35 80 1.456473214 2 40 0.8 80 0.454545455
0.454545
3 Bedroom 2 4.3 3.9 120 16.77 0.49 20 4.278061224 6 60 1 360 1.636363636
1.636364
3 Balcony 2 4.1 2.2 50 9.02 0.49 20 0.958758503 1 60 1 60 0.272727273
0.272727
4 Bedroom 3 4.9 3.8 120 18.62 0.49 20 7.125 6 40 1 240 1.090909091
1.0909
4 Bedroom 3-Closte 2.1 1.9 120 3.99 0.49 20 1.017857143 1 60 1 60 0.272727273
0.272
4 Bathroom 3 2 1.9 300 3.8 0.35 80 1.272321429 2 40 0.8 80 0.454545455
0.454
205.46 Sum 3.75 3.659091 4.272727 4.453264
CB rating 4.5 4.390909 5.127273 5.343916
closest CB 10 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
17
b) Normal & Power Sockets:
line Type Current C.B rating MCB C.S.A
line 1 Lighting 3.75 4.5 10 3*2.5 mmยฒ
line 2 Lighting 3.66 4.392 10 3*2.5 mmยฒ
line 3 Lighting 4.273 5.1276 10 3*2.5 mmยฒ
line 4 Lighting 4.453 5.3436 10 3*2.5 mmยฒ
line 5 Normal sockets 4.4 5.28 10 3*4 mmยฒ
line 6 Normal sockets 4 4.8 10 3*4 mmยฒ
line 7 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 8 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 9 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 10 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 11 AC 8.477 10.1724 25 3*6 mmยฒ
line 12 AC 8.477 10.1724 25 3*6 mmยฒ
line 13 AC 8.477 10.1724 25 3*6 mmยฒ
line 14 AC 8.477 10.1724 25 3*6 mmยฒ
line 15 Washing machine 7.57 9.084 16 3*4 mmยฒ
line 16 Dryer 7.57 9.084 16 3*4 mmยฒ
line 17 Water Heater 7.57 9.084 16 3*4 mmยฒ
line 18 Water Heater 7.57 9.084 16 3*4 mmยฒ
Power sockets calculations:
Type Current Calculations
Air conditioner (2.25 HP): ๐ฐ๐จ๐ช =
๐.๐๐โ๐๐๐
๐๐๐โ๐.๐= ๐.๐๐๐ ๐จ (normal current)
=8.477ร1.25=10.59 A (Starting current)
Water Heater: ๐ฐ๐พ๐ฏ =๐๐๐๐
๐๐๐ โ ๐.๐= ๐.๐๐ ๐จ
Washing machine: ๐ฐ๐พ๐ด =๐๐๐๐
๐๐๐ โ ๐.๐= ๐.๐๐ ๐จ
Dryer: ๐ฐ๐ซ๐๐๐๐ =๐๐๐๐
๐๐๐ โ ๐.๐= ๐.๐๐ ๐จ
CHAPTER 2 BUILDING WIRING CALCULATION
18
c) KVA calculation:
ฮฃ light =3.75+3.659091+4.272727+4.453264= 16.13 A.
ฮฃ Normal sockets=4.4+4+ (3.6ร4) =22.8 A.
ฮฃ Power sockets= (8.477ร4) + (7.57ร2) + (7.57ร2) =64.188 A.
โด ๐ฐ๐๐๐๐=0.7[16.13+22.8+64.188] =72.6 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐=72.6ร220=15.9 KVA.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =72.6
3= 24.2 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร16 mmยฒ.
Meter used = 40A Three phase meter.
Phase balance:
Phase R Phase S Phase T
Line Current Line Current Line Current
Lighting L1 3.75 L3 4.273 L4 4.453
L2 3.659
Normal Sockets L5 4.4 L7 3.6 L9 3.6
L6 4 L8 3.6 L10 3.6
Power Sockets
L11 8.477 L13 8.477 L16 7.57
L12 8.477 L14 8.477 L17 7.57
L15 7.57 L18 7.57
Sum
32.763
35.997
34.363
d) Riser calculation: We will have 24 building of this type, each of 12 apartments in 6 floors.
From diversity graph, we get the diversified KVA of flat.
โด ๐ฒ๐ฝ๐จ๐๐๐๐(๐ ๐๐๐๐๐๐๐๐๐ ) =7.9 KVA.
โด ๐ฒ๐ฝ๐จ๐ฉ๐๐๐๐ ๐๐๐=7.9ร12=94.8 KVA.
โด ๐ฐ๐น๐๐๐๐ =94.8โ103
380 3 =144.03 A.
Then, Fuse=160 A (3 phase).
C.S.A =3ร70+35+35 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
19
Fig 2.1 Distribution of lighting in flat type (A).
CHAPTER 2 BUILDING WIRING CALCULATION
20
Fig 2.2 Distribution of Sockets in flat type (A).
CHAPTER 2 BUILDING WIRING CALCULATION
21
ยฒ
ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒยฒยฒยฒยฒยฒยฒ
ยฒ ยฒ ยฒ
Fig 2.3 Distribution board in flat type (A).
CHAPTER 2 BUILDING WIRING CALCULATION
22
Fig 2.4 Riser diagram in flat type (A).
ยฒ
ยฒ
ยฒ
2.7.2 Flat type (B)
a) Lighting:
Line room length width Lux Area u ฦ number of
lamps lamps
lamps wattage
power factor
installed wattage
lamp current line 1 line2
2 entrance 1.35 1.4 50 1.89 0.49 20 0.20089286 2 60 1 120 0.545454545
0.5454
2 Saloon 6.35 3.85 150 24.4475 0.49 20 7.79575893 8 60 1 480 2.181818182
2.1818
2 bed room 1 4.05 3.5 120 14.175 0.49 20 3.61607143 4 60 1 240 1.090909091
1.0909
2 balcony 1 2 3.5 50 7 0.49 20 0.74404762 1 60 1 60 0.272727273
0.2727
2 bed room 2 5.25 3.45 120 18.1125 0.49 20 4.62053571 5 60 1 300 1.363636364
1.3636
1 bed room 3 5.45 4.2 120 22.89 0.49 20 5.83928571 6 60 1 360 1.636363636 1.636
1 balcony 2 1.1 1.1 50 1.21 0.49 20 0.12861395 1 60 1 60 0.272727273 0.27
1 kitchen 2.6 3.5 300 9.1 0.41 80 2.60099085 3 40 0.8 120 0.681818182 0.6818
1
0.7 0.7
1 small bathroom 2.6 1.1 300 2.86 0.35 80 0.95758929 1 40 0.8 40 0.227272727 0.227
1
1 1 25 0.8 25 0.142045455 0.142
1
0.7 0.7
1 big bathroom 2.6 1.75 300 4.55 0.35 80 1.5234375 2 40 0.8 80 0.454545455 0.45455
1
1 1 25 0.8 25 0.142045455 0.142
1
0.7 0.7
1 corridor 1.1 4.8 50 5.28 0.49 20 0.56122449 1 60 1 60 0.272727273 0.273
111.515
Sum 5.92635 5.4544
CB rating 7.11162 6.54528
closest CB 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
24
b) Normal & Power Sockets:
Line Type calculations current Column1 C.B C.S.A
line 1 Lighting - 5.92 - 10 3ร2.5 mmยฒ
line 2 Lighting - 5.45 - 10 3ร2.5 mmยฒ
line 3 normal sockets 2+.2(6x2) 4.4 5.28 10 3ร4 mmยฒ
line 4 normal sockets 2+.2(6x2) 4.4 5.28 10 3ร4 mmยฒ
line 5 normal sockets 2+.2(6x2) 4.4 5.28 10 3ร4 mmยฒ
line 6 ID55 (1500/220x0.9) 7.57 9.084 16 3ร4 mmยฒ
line 7 AC 2.25x746/(220x0.9) 8.477 10.1724 25 3ร6 mmยฒ
c) KVA calculation:
ฮฃ light =5.92+5.45= 11.37 A.
ฮฃ Normal sockets=4.4ร3 =13.2.
ฮฃ Power sockets=0.5ร [8.477+7.57] =8.0235 A.
โด ๐ฐ๐๐๐๐=0.7[11.37+13.2+8.0235] =22.8 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐=22.8ร220=5 KVA.
Then,
M.C.B=32 A (Single phase).
C.S.A =3ร10 mmยฒ.
Meter used = 40A Single phase meter.
d) Riser calculation: We will have 101 building of this type, each of 24 apartments in 6 floors.
From diversity graph, we get the diversified KVA of flat.
โด ๐ฒ๐ฝ๐จ๐๐๐๐(๐ ๐๐๐๐๐๐๐๐๐ ) =1.9 KVA.
โด ๐ฒ๐ฝ๐จ๐ฉ๐๐๐๐ ๐๐๐=1.9ร24= 45.6 KVA.
โด ๐ฐ๐น๐๐๐๐ =45.6โ103
380 3 =69.28 A.
Then,
Fuse=80 A (3 phase).
C.S.A =3ร25+25+25 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
25
Fig 2.5 Distribution of lighting in flat type (B).
Fig 2.6 Distribution of Sockets in flat type (B).
CHAPTER 2 BUILDING WIRING CALCULATION
26
ยฒ
ยฒ
ยฒ
Fig 2.7 Distribution board in flat type (B).
Fig 2.8 Riser diagram in flat type (B)
ยฒ ยฒ
ยฒ ยฒ ยฒ
ยฒ
ยฒ ยฒ
2.7.3 Flat type (C)
a) Lighting:
Line room length width Lux Area u ฦ number of
lamps lamps
lamps wattage
power factor
installed wattage
lamp current line 1 line2
1 entrance 2.06 1.3 50 2.678 0.49 20 0.28465136 2 60 1 120 0.545454545 0.5454
1 reception 7.8 5.35 150 41.73 0.49 20 13.3067602 14 60 1 840 3.818181818 3.818
1 trace 2.1 4.7 50 9.87 0.49 20 1.04910714 2 60 1 120 0.545454545 0.5454
1 bed room 1 3.6 5 120 18 0.49 20 4.59183673 5 60 1 300 1.363636364 1.3636
1 bathroom 1 1.7 2.7 300 4.59 0.35 80 1.53683036 2 40 0.8 80 0.454545455 0.4545
1
1 1 25 0.8 25 0.142045455 0.142
1
0.7 0.7
2 entrance bathroom 1 1.7 1.9 50 3.23 0.49 20 0.34332483 1 60 1 60 0.272727273
0.2727
2 bed room 2 3.7 3.7 120 13.69 0.49 20 3.49234694 5 60 1 300 1.363636364
1.3636
2 corridor 1.05 3.82 50 4.011 0.49 20 0.42633929 1 60 1 60 0.272727273
0.2727
2 bathroom 2 1.7 2.7 300 4.59 0.35 80 1.53683036 2 40 0.8 80 0.454545455
0.4545
2
1 1 25 0.8 25 0.142045455
0.142
2
0.7
0.7
2 entrance bathroom 2 1.7 1.89 50 3.213 0.49 20 0.34151786 1 60 1 60 0.272727273
0.2727
2 bedroom 3 3.9 4.78 120 18.642 0.49 20 4.75561224 5 60 1 300 1.363636364
1.3636
2 entrance bathroom 3 1.7 1.1 50 1.87 0.49 20 0.19876701 1 60 1 60 0.272727273
0.2727
2 bathroom 3 2.1 1.3 300 2.73 0.35 80 0.9140625 1 40 0.8 40 0.227272727
0.227
2
1 1 25 0.8 25 0.142045455
0.142
2
0.7
0.7
2 kitchen 3.7 2.6 300 9.62 0.41 80 2.7496189 3 40 0.8 120 0.681818182
0.6818
2
0.7
0.7
138.46
sum 7.5689 7.5653
C.B rating 9.08268 9.07836
Closet C.B 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
28
b) Normal & Power Sockets:
Line Type calculations current Column1 C.B C.S.A
line 1 Lighting - 7.57 - 10 3*2.5 mmยฒ
line 2 Lighting - 7.57 - 10 3*2.5 mmยฒ
line 3 normal sockets 2+.2(6x2) 4.4 5.28 10 3*4 mmยฒ
line 4 normal sockets 2+.2(4x2) 3.6 4.32 10 3*4 mmยฒ
line 5 normal sockets 2+.2(4x2) 3.6 4.32 10 3*4 mmยฒ
line 6 normal sockets 2+.2(6x2) 4.4 5.28 10 3*4 mmยฒ
line 7 ID55 (1500/220x0.9) 7.57 9.084 16 3*4 mmยฒ
line 8 ID55 (1500/220x0.9) 7.57 9.084 16 3*4 mmยฒ
line 9 AC 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line 10 AC 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
c) KVA calculation:
ฮฃ light =7.57+7.57= 15.14 A.
ฮฃ Normal sockets=4.4+3.6+3.6+4.4 =16 A.
ฮฃ Power sockets=0.5ร [2ร8.477+2ร7.57] =16.047 A.
โด ๐ฐ๐๐๐๐=0.7[15.14+16+16.047] =33 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐=33ร220=7.263 KVA.
Then,
M.C.B=40 A (Single phase).
C.S.A =3ร16 mmยฒ.
Meter used = 40A Single phase meter.
d) Riser calculation: We will have 145 building of this type, each of 24 apartments in 6 floors.
From diversity graph, we get the diversified KVA of flat.
โด ๐ฒ๐ฝ๐จ๐๐๐๐(๐ ๐๐๐๐๐๐๐๐๐ ) =2.8 KVA.
โด ๐ฒ๐ฝ๐จ๐ฉ๐๐๐๐ ๐๐๐=2.8ร24= 67.2 KVA.
โด ๐ฐ๐น๐๐๐๐ =67.2โ103
380 3 =102.1 A.
Then,
Fuse=160 A (3 phase).
C.S.A =3ร70+35+35 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
29
Fig 2.9 Distribution of lighting in flat type (C).
Fig 2.10 Distribution of Sockets in flat type (C).
CHAPTER 2 BUILDING WIRING CALCULATION
30
Fig 2.11 Distribution board in flat type (C).
ยฒ ยฒ
ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
CHAPTER 2 BUILDING WIRING CALCULATION
31
Fig2.12 Riser diagram in flat type (B).
ยฒ
ยฒ
ยฒ
2.7.4 Flat type (D)
a) Lighting:
room Lux Area u ฦ number of lamps lamps lamps wattage power factor installed wattage lamp current line 1 line 2 line 3 line 4 line5
Door entrance 50 3.9 0.49 20 0.622 1 40 1 40 0.181818
0.182
Saloon 150 82 0.49 20 15.69 16 100 1 1600 7.272727 3.637 3.637
Hall entrance 50 7 0.49 20 0.744 1 60 1 60 0.272727
0.273
Kitchen 300 17.85 0.41 80 5.102 6 40 0.8 240 1.363636
1.364
Path 1 50 3.25 0.49 20 0.345 1 60 1 60 0.272727
0.273
Path 2 50 12 0.49 20 1.276 2 60 1 120 0.545455
0.545
Path 3 50 4.75 0.49 20 0.505 1 60 1 60 0.272727
0.273
Living room 150 20.4 0.49 20 3.903 4 100 1 400 1.818182
1.818
Bathroom 1 300 4.42 0.35 80 1.48 2 40 0.8 80 0.454545
0.455
Bathroom 2 300 4.9 0.35 80 1.641 2 40 0.8 80 0.454545
0.455
Bathroom 3 300 5.2 0.35 80 1.741 2 40 0.8 80 0.454545
0.455
Nanny room 120 5.5 0.49 20 1.403 2 60 1 120 0.545455
0.545
Nanny's bath 200 2.6 0.35 80 0.58 1 40 0.8 40 0.227273
0.227
Bedroom 1 120 20.4 0.49 20 5.204 6 60 1 360 1.636364
1.636
Bedroom 2 120 18.4 0.49 20 4.694 5 60 1 300 1.363636
1.364
Extension 50 5.66 0.49 20 0.602 1 60 1 60 0.272727
0.273
Bedroom 3 120 20 0.49 20 5.102 6 60 1 360 1.636364
1.636
Balcony 50 6 0.49 20 0.638 1 60 1 60 0.272727
0.273
244.2
Sum 3.637 3.909 3.182 4.409 4
CB rating 4.364 4.691 3.818 5.291 4.8
closest CB 10 10 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
33
b) Normal & Power Sockets:
Line Type Current C.B M.C.B C.S.A
line 1 Lighting 3.6365 4.3638 10 3*2.5 mmยฒ
line 2 Lighting 4.1825 5.019 10 3*2.5 mmยฒ
line 3 Lighting 2.909 3.4908 10 3*2.5 mmยฒ
line 4 Lighting 4.411 5.2932 10 3*2.5 mmยฒ
line 5 Lighting 3.185 3.822 10 3*2.5 mmยฒ
line 6 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 7 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 8 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 9 Normal sockets 3.2 3.84 10 3*4 mmยฒ
line 10 Normal sockets 3.6 4.32 10 3*4 mmยฒ
line 11 Normal sockets 4.4 5.28 10 3*4 mmยฒ
line 12 Normal sockets 4.4 5.28 10 3*4 mmยฒ
line 13 Normal sockets 4.4 5.28 10 3*4 mmยฒ
line 14 AC 8.477 10.1724 25 3*6 mmยฒ
line 15 AC 8.477 10.1724 25 3*6 mmยฒ
line 16 AC 8.477 10.1724 25 3*6 mmยฒ
line 17 AC 8.477 10.1724 25 3*6 mmยฒ
line 18 Water Heater 7.576 9.0912 16 3*4 mmยฒ
line 19 Water Heater 7.576 9.0912 16 3*4 mmยฒ
line 20 Dryer 7.576 9.0912 20 3*6 mmยฒ
line 21 Washing machine 7.576 9.0912 20 3*6 mmยฒ
c) KVA calculation:
ฮฃ light =3.63+4.183+2.91+4.411+3.185= 18.32 A.
ฮฃ Normal sockets=3.2+ (4.4ร3) + (3.6ร4) =30.8 A.
ฮฃ Power sockets= (8.477ร4) + (7.57ร2) + (7.57ร2) =64.188 A.
โด ๐ฐ๐๐๐๐=0.7[18.32+30.8+64.188] =79.3156 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐=79.3156ร220=17.4 KVA.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =79.1356
3= 26.4 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร16 mmยฒ.
Meter used = 40A Three phase meter.
CHAPTER 2 BUILDING WIRING CALCULATION
34
Phase balance:
Phase R Phase S Phase T
Line Current Line Current Line Current
Lighting L1 3.6365 L3 3.182 L5 4
L2 3.91 L4 4.41
Normal Sockets
L6 3.6 L10 3.6 L12 4.4
L7 3.6 L11 4.4 L13 4.4
L8 3.6
L9 3.2
Power Sockets
L18 7.576 L15 8.477 L14 8.477
L19 7.576 L16 8.477 L17 8.477
L20 7.576 L21 7.576
Sum
36.6985
40.122
37.33
d) Riser calculation: We will have 57 building of this type, each of 12 apartments in 6 floors.
From diversity graph, we get the diversified KVA of flat.
โด ๐ฒ๐ฝ๐จ๐๐๐๐(๐ ๐๐๐๐๐๐๐๐๐ ) =8.2 KVA.
โด ๐ฒ๐ฝ๐จ๐ฉ๐๐๐๐ ๐๐๐=8.2ร12=98.4 KVA.
โด ๐ฐ๐น๐๐๐๐ =98.4โ103
380 3 =149.5 A.
Then, Fuse=160 A (3 phase).
C.S.A =3ร70+35+35 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
35
Fig 2.13 Distribution of lighting in flat type (D).
CHAPTER 2 BUILDING WIRING CALCULATION
36
Fig 2.14 Distribution of Sockets in flat type (D).
CHAPTER 2 BUILDING WIRING CALCULATION
37
Fig 2.15 Distribution board in flat type (D).
ยฒ
ยฒ
ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
ยฒยฒยฒยฒยฒยฒยฒยฒ ยฒ ยฒ ยฒ
CHAPTER 2 BUILDING WIRING CALCULATION
38
Fig 2.16 Riser diagram in flat type (D).
ยฒ
ยฒ
ยฒ
2.7.5 Flat type (E)
Repeated apartments:
a) Lighting:
Line 2 Line 1 Current Total
Wattage (Positions x N lamps x Watt)
Wattage needed
Illumination Type
Area Dimensions Lux Room
8.18 8.18 1800 3x3x200 1764 Incandescent 44.1 5.4*3.7+3.6*6.7 200 Open Salon Living
0.45 0.45 100 1x1x100 77 Incandescent 7.7 2.14*3.6 50 Balcony
0.45 0.45 80 1x2x40 72.216 Florescent 3.54 2.36*1.5 300 Guest's Bathroom
1.82
1.82 320 2x4x40 293.76 Florescent 14.4 4*3.6 300 Kitchen
0.45 0.45 100 1x100 70.8 Incandescent 3.54 1.5*2.36 100 Entrance
2 2 450 3x1x150 439 Incandescent 8.78 1.12*7.84 50 Hallway
1.82
1.82 400 1x4x100 388.8 Incandescent 12.96 3.6*3.6 150 Children's Bedroom
0.27
0.27 60 1x1x60 55.7 Incandescent 5.57 2.36*2.36 50 Room Entrance
Hallway
0.68
0.68 120 1x3x40 113.628 Florescent 5.57 2.36*2.36 300 Children's Bathroom
3.64
3.64 800 2x2x200 790.5 Incandescent 26.35 7.32*3.6 150 Master Bedroom
0.68
0.68 150 1x1x150 124.5 Incandescent 4.15 1.76*2.36 150 Changing Room
0.68
0.68 120 1x3x40 112.2 Florescent 5.5 2.36*2.33 300 Master Bathroom
line2=9.59A line1=11.53A Total
Current=21.12A Total Area
=142.16
6.32A 7.61A Diversified
current
10 10 C.B
CHAPTER 2 BUILDING WIRING CALCULATION
40
b) Normal & Power Sockets:
Normal Socket Lines Calculations For Repeated apartments
Div. Line Current Rating
Number of 5A Sockets
Number of 3A Sockets Normal Sockets
Lines
5.4 0 5 S1
8.2 3 2 S2
7.8 2 3 S3
7.4 1 4 S4
5.4 0 5 S5
7.6 3 1 S6
Power Socket Lines Rating For Repeated Apts
Line Current Rating
Assuming 0.7 p.f
Kwatt Rating
Air Cond.Rating
in Hp
Horse Power needed
10sqm/hp
Air Cond. Coverage
Area
Power Sockets
Lines
14.5 2.24 3 2.2 22 P1
14.5 2.24 3 2.2 22 P2
7.27 1.12 1.5 1.44 14.4 P3
7.27 1.12 1.5 1.3 13 P4
14.5 2.24 3 2.6 26 P5
Repeated Apt CBs And CSAs
CSA MCB Current Line
3x2.5mm2 10 7.61 L1
3x2.5mm2 10 6.32 L2
3x2mm2 10 5.4 S1
3x2mm2 10 8.2 S2
3x2mm2 10 7.8 S3
3x2mm2 10 7.4 S4
3x2mm2 10 5.4 S5
3x2mm2 10 7.6 S6
3x3mm2 15 7.27 P1
3x3mm2 15 7.27 P2
3x6mm2 32 14.5 P3
Ground floor apartment:
a) Lighting:
Line 4 Line 3 Line 2 Line 1 Current Total
Wattage
(Positions x N.lamps
x Watt)
Wattage needed
Illumination Type
Area Width Length Lux Room
0.18 0.18 40 1x1x40 15.25 Incandescent 1.525 1.22 1.25 50 Door 1
4.1 4.1 900 1x6x150 898.4 Incandescent 22.4576 4.64 4.84 200 Salon
0.27 0.27 60 1x1x60 57 Incandescent 5.7112 4.84 1.18 50 Balcony 1
5.45 5.45 1200 1x8x150 1159.6 Incandescent 28.9916 4.84 5.99 200 Dining
0.45
0.45 80 1x2x40 77 Florescent 3.776 2.36 1.6 300 Guest's Bathroom
0.18
0.18 40 1x1x40 37.76 Incandescent 3.776 2.36 1.6 50 Entrance hall
0.36
0.36 80 2x1x40 54.2 Incandescent 5.4208 1.12 4.84 50 Hall 1
0.68
0.68 120 1x3x40 96.3 Florescent 7.08 2.36 3 200 Laundry Room
0.45
0.45 80 1x2x40 82.8 Florescent 4.0592 1.72 2.36 300 Maid's Bathroom
2.05
2.05 360 3x3x40 352.512 Florescent 17.28 3.6 4.8 300 Kitchen
2.27
2.27 500 1x5x100 522.72 Incandescent 17.424 3.6 4.84 150
Children's Bedroom
0.18
0.18 40 1x1x40 15.25 Incandescent 1.525 1.22 1.25 50 Door 2
10.9
10.9 2400 3x4x200 2156.7 Incandescent 53.9176 4.84 11.14 200 Reception
0.27
0.27 60 1x1x60 57 Incandescent 5.7112 4.84 1.18 50 Balcony 2
0.55
0.55 120 3x1x40 62.5 Incandescent 6.2496 1.12 5.58 50 Hall 2
0.9
0.9 200 1x5x40 180.54 Florescent 8.8485 3.47 2.55 300 Master Bathroom
1.36
1.36 300 1x2x150 274.5 Incandescent 9.1516 3.34 2.74 150 Changing Room
2.73
2.73 600 1x4x150 612.6 Incandescent 20.4248 4.22 4.84 150 Master Bedroom
2.73
2.73 600 1x4x150 580.8 Incandescent 19.36 4.84 4 150 Living
0.55
0.55 120 1x3x40 114.2 Incandescent 11.4224 4.84 2.36 50 Balcony 3
8.27 11.35 6.99 10 Sum
5.46 7.49 4.61 6.6 Diversified
current
10 10 10 10 C.B.
CHAPTER 2 BUILDING WIRING CALCULATION
42
b) Normal & Power Sockets:
Normal Socket Lines Calculations For Ground floor Apt.
Div. Line Current Rating
Number of 10A Sockets
Number of 5A Sockets Normal Socket
Lines
10 0 6 S1
18 3 4 S2
15 1 5 S3
11 0 7 S4
10 0 6 S5
15 1 5 S6
Power Socket Lines Calculations For Ground floor Apt.
Current Assuming 0.7 p.f Wattage Power Use Power Sockets Lines
14.5 2.23 3hp Air Cond P1
14.5 2.23 3hp Air Cond P2
9.74 1.5 2hp Air Cond P3
9.74 1.5 2hp Air Cond P4
14.5 2.23 3hp Air Cond P5
14.5 2.23 3hp Air Cond P6
14.5 2.23 3hp Air Cond P7
14.5 2.23 3hp Air Cond P8
32.47 5 __ Washer+Dryer P9
Panel 1 Lines
Phase T Phase S Phase R CSA(mmยฒ) MCB Current Lines
6.6
3x2.5 10 6.6 L1
4.61 3x2.5 10 4.61 L2
7.49
3x2.5 10 7.49 L3
5.46 3x2.5 10 5.46 L4
10 3x3 15 10 S1
18
3x4 20 18 S2
15
3x4 20 15 S3
11 3x3 15 11 S4
10
3x3 15 10 S5
15
3x4 20 15 S6
14.5 3x6 32 14.5 P1
14.5 3x6 32 14.5 P2
9.74 3x4 20 9.74 P3
9.74
3x4 20 9.74 P4
14.5 3x6 32 14.5 P5
14.5
3x6 32 14.5 P6
14.5
3x6 32 14.5 P7
14.5
3x6 32 14.5 P8
32.47
3x10 40 32.47 P9
78.57 79.23 84.31
242.11
IT Div0 =46.97A IS Div0 =33.438A IR Div0 =36.518A
CHAPTER 2 BUILDING WIRING CALCULATION
43
c) KVA calculation:
โด ๐ฐ๐๐๐๐=(7.61+6.32)+14.5+0.2[7.27ร2+5.4ร2+7.8+7.4+8.2+7.6] =39.698 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐=39.698ร220=8.733 KVA.
Then,
M.C.B=63 A (Single phase).
C.S.A =3ร16 mmยฒ.
Meter used = 40A Single phase meter.
d) Riser calculation: We will have 116 building of this type, each of 10 apartments in 4 floors.
From diversity graph, we get the diversified KVA of flat.
โด ๐ฒ๐ฝ๐จ๐๐๐๐(๐ ๐๐๐๐๐๐๐๐๐ ) =6.5 KVA.
โด ๐ฒ๐ฝ๐จ๐ฉ๐๐๐๐ ๐๐๐=6.5ร10=65 KVA.
โด ๐ฐ๐น๐๐๐๐ =65โ103
380 3 =98.757 A.
Then, Fuse=160 A (3 phase).
C.S.A =3ร70+35+35 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
44
Fig 2.17 Distribution of lighting in flat type repeated (E).
CHAPTER 2 BUILDING WIRING CALCULATION
45
Fig 2.18 Distribution of Sockets in flat type repeated (E).
CHAPTER 2 BUILDING WIRING CALCULATION
46
Fig 2.19 Distribution of Light in flat type zero floor (E).
CHAPTER 2 BUILDING WIRING CALCULATION
47
Fig 2.20 Distribution of Sockets in flat type zero floor (E).
2.7.6 Villa type (A)
Ground Floor:
a) Lighting:
line room length width Lux Area ฦ u lamp type
watt no of lamps
lamps wattage
power factor
installed wattage
lamp current
current line 1 line 2 line 3 line 4 line5 line6
3 villa
entrance1 _ _ 50 225.5 20 0.49 0.2 2255 22 60 1 1320 6 6
6
5 villa
entrance2 _ _ 50 70 20 0.49 0.2 700 12 100 1 1200 5.454545 5.454545
5.45
6 entrance 1 1.06 4.25 50 4.505 20 0.49 0.2 45.05 1 40 1 40 0.181818 0.181818
0.181
6 kitchen1 3.95 4.2 300 16.59 80 0.41 0.0683 339.9291 8 40 0.8 320 1.818182 1.818182
1.818
1 bath1 2.22 3.29 300 7.3038 80 0.35 0.0683 149.654862 3 40 0.8 120 0.681818 1.381818 1.38
4 corridor1 2.22 1.59 100 3.5298 20 0.49 0.2 70.596 1 40 1 40 0.181818 0.181818
0.1818
1 bed room 1 4.88 5.26 150 25.669 20 0.41 0.2 770.064 8 100 1 800 3.636364 3.636364 3.63
5 nani2 3 1.88 150 5.64 20 0.35 0.2 169.2 4 40 1 160 0.727273 0.727273
0.72
5 bath4 1.96 2.46 300 4.8216 80 0.49 0.0683 98.794584 2 40 0.8 80 0.454545 1.154545
1.15
3 corridor4 3.87 1.2 50 4.644 20 0.49 0.2 46.44 1 20 1 20 0.090909 0.090909
0.0909
6 dinning 2 5.22 4.2 200 21.924 20 0.35 0.2 876.96 8 100 1 800 3.636364 3.636364
3.6363
3.636
4 sallon1 a 6.66 3.75 150 24.975 20 0.49 0.2 749.25 8 100 1 800 3.636364 3.636364
2 sallon1 b 9.88 6.19 150 61.157 20 0.49 0.2 1834.716 20 100 1 2000 9.090909 9.090909
9.09
1 stairs 4.8 3.7 100 17.76 20 0.49 0.2 355.2 6 60 1 360 1.636364 1.636364 1.63
9 hall 3.26 9.15 150 29.829 20 0.49 0.2 894.87 18 40 1 720 3.272727 3.272727
2 trace2 4.52 1.42 50 6.4184 20 0.49 0.2 364.952 1 40 1 40 0.181818 0.181818
0.1818
Sum 6.65 9.2718 6.0909 3.8181 7.33 5.636
CB rating 7.98 11.126 7.3090 4.5818 8.80 6.763
closest CB 10 10 10 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
49
b) Normal & Power Sockets:
Line Type current MCB CSA
1 light 6.65 10 3*2.5mmยฒ
2 light 9.27 10 3*2.5mmยฒ
3 light 6.09 10 3*2.5mmยฒ
4 light 4.27 10 3*2.5mmยฒ
5 light 7.34 10 3*2.5mmยฒ
6 light 5.64 10 3*2.5mmยฒ
7 Spare
8 Normal sockets 4.4 10 3*4mmยฒ
9 Normal sockets 4.4 10 3*4mmยฒ
10 Normal sockets 4.8 10 3*4mmยฒ
11 Normal sockets 4.4 10 3*4mmยฒ
12 Normal sockets 4 10 3*4mmยฒ
13 Power Socket 7.57 16 3*4mmยฒ
14 Power Socket 7.57 16 3*4mmยฒ
15 Water heater 7.57 16 3*4mmยฒ
16 Water heater 7.57 16 3*4mmยฒ
17 AC 8.48 25 3*6mmยฒ
18 AC 8.48 25 3*6mmยฒ
19 AC 8.48 25 3*6mmยฒ
20 AC 8.48 25 3*6mmยฒ
c) KVA calculation:
ฮฃ light =6.65+7.27+6.09+4.27+7.34+5.64= 29.92 A.
ฮฃ Normal sockets=4 + (4.4ร3) + 4.8 =22 A.
ฮฃ Power sockets= 0.5[(8.48ร4) + (7.57ร2) + (7.57ร2)] =32.1 A.
โด ๐ฐ๐๐๐๐=0.7[29.92+22+32.1] =65.35 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐๐๐ =65.35ร220=14.377 KVA.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =65.35
3= 21.78 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร10 mmยฒ.
First Floor:
a) Lighting: line room length width Lux Area
lamp type
watt number of
lamps lamps
wattage power factor
installed wattage lamp
current Line 1 Line 2 Line 3 Line 4 Line 5 Line 6
5 trace1 1.18 3.68 50 4.342 0.2 43.42 1 40 1 40 0.182
0.182
5 bedroom1 4.2 4.15 150 17.43 0.2 522.9 6 100 1 600 2.727
2.727
5 bath1 2.16 3.36 300 7.258 0.063 137.8 3 40 0.8 120 0.682
0.682
4 corridor1 2.34 1.76 100 4.118 0.2 82.37 1 40 1 40 0.182
0.182
4 bedroom2 4.82 5.3 150 25.55 0.2 766.4 6 100 1 600 2.727
2.727
4 bath 2 2.88 1.77 300 5.098 0.068 104.4 3 40 0.8 120 0.682
1.382
4 office 1 2.48 2.08 250 5.158 0.068 88.08 3 40 0.8 120 0.682
0.364
4 corridor 2 1.1 8.03 50 8.833 0.2 88.33 2 40 1 80 0.364
2.727
3 bedroom 3 5.3 4.15 150 22 0.2 659.9 6 100 1 600 2.727
2.727
6 bath 3 5.22 1.86 300 9.709 0.068 198.9 5 40 0.8 200 1.136
1.364
6 dressing room1
5.2 2.88 150 14.98 0.2 449.3 4 100 1 400 1.818
1.818
2 stairs 4.72 4.8 100 22.66 0.2 453.1 6 100 1 600 2.727
2.727
1 living room 5.6 6.08 200 34.05 0.2 1362 10 150 1 1500 6.818 6.818
6 bedroom 4 5.34 4.88 150 26.06 0.2 781.8 8 100 1 800 3.636
3.636
3.636
1 trace 2 5.22 1.06 50 5.533 0.2 55.33 2 40 1 80 0.364 0.364
3 trace 3 6.08 1.2 50 7.296 0.2 72.96 2 40 1 80 0.364
0.364
Sum 7.182 2.727 6.727 7.382 3.591 6.818
CB rating 8.6181 3.2727 8.0726 8.8580 4.3089 8.1817
closest
CB 10 10 10 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
51
b) Normal & Power Sockets:
line type current MCB CSA
1 light 7.18 10 3*2.5mmยฒ
2 light 2.73 10 3*2.5mmยฒ
3 light 6.73 10 3*2.5mmยฒ
4 light 7.38 10 3*2.5mmยฒ
5 light 6.82 10 3*2.5mmยฒ
6 light 6.82 10 3*2.5mmยฒ
7 light spare 10 3*2.5mmยฒ
8 Normal Sockets 4.4 10 3*4mmยฒ
9 Normal Sockets 4.4 10 3*4mmยฒ
10 Normal Sockets 3.2 10 3*4mmยฒ
11 Normal Sockets 4.4 10 3*4mmยฒ
12 Normal Sockets 3.2 10 3*4mmยฒ
13 Normal Sockets 4.4 10 3*4mmยฒ
14 Power Sockets 7.57 20 3*6mmยฒ
15 Water heater 7.57 16 3*4mmยฒ
16 Water heater 7.57 16 3*4mmยฒ
17 Water heater 7.57 16 3*4mmยฒ
18 AC 8.48 25 3*6mmยฒ
19 Water heater 7.57 16 3*4mmยฒ
20 AC 8.48 25 3*6mmยฒ
d) KVA calculation:
ฮฃ light =7.18+2.73+6.73+7.38+6.82+6.82= 37.66 A.
ฮฃ Normal sockets= (4.4ร4) + (3.2ร2) =24 A.
ฮฃ Power sockets= 0.5[(8.48ร2) + (7.57ร4) + (7.57)] =27.405 A.
โด ๐ฐ๐๐๐๐=0.7[37.66+24+27.405] =62.34 A.
โด ๐ฒ๐ฝ๐จ๐ญ๐๐๐๐=62.34ร220=13.716 KVA.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =62.34
3= 20.78 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร10 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
52
Garage:
line current MCB CSA
1 1.818 10 3*2.5mmยฒ
2 2.727 10 3*2.5mmยฒ
3 2.045 10 3*2.5mmยฒ
4 2.045 10 3*2.5mmยฒ
5 2.727 10 3*2.5mmยฒ
6 0.682 10 3*2.5mmยฒ
7 7.57 20 3*6mmยฒ
8 7.57 20 3*6mmยฒ
9 7.57 20 3*6mmยฒ
10 7.57 20 3*6mmยฒ
KVA calculation:
ฮฃ light =1.818+2.727+2.045+2.045+2.727+0.682= 10 A.
ฮฃ Power sockets= 0.5[(7.57ร4)] =15.14 A.
โด ๐ฐ๐๐๐๐=0.7[10+15.14] =19.66 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐๐๐ =19.66ร220=4.325 KVA.
Then,
M.C.B=32 A (Single phase).
C.S.A =3ร10 mmยฒ.
Riser calculation: We will have 26 building of this type, each of 2 apartments duplex.
we get the diversified KVA of apartment.
โด ๐ฒ๐ฝ๐จ๐๐๐๐๐๐๐๐๐(๐ ๐๐๐๐๐๐๐๐๐ ) =0.7[14.377+13.7] =19.66 KVA.
โด ๐ฒ๐ฝ๐จ๐๐๐๐๐=19.66ร2+4.18=31.7 KVA.
โด ๐ฐ๐น๐๐๐๐ =31.7โ103
380 3 =48.16 A.
Then, Fuse=63 A (3 phase).
C.S.A =3ร25+25+25 mmยฒ.
Meter used = 80A Three phase meter.
CHAPTER 2 BUILDING WIRING CALCULATION
53
Fig 2.21 Distribution of Light in Villa type (A) ground floor.
CHAPTER 2 BUILDING WIRING CALCULATION
54
Fig 2.22 Distribution of Sockets in Villa type (A) ground floor.
CHAPTER 2 BUILDING WIRING CALCULATION
55
Fig 2.23 Distribution of lighting in Villa (A) First floor.
CHAPTER 2 BUILDING WIRING CALCULATION
56
Fig 2.24 Distribution of Sockets in Villa (A) First floor.
CHAPTER 2 BUILDING WIRING CALCULATION
57
Fig 2.25 Distribution board in Villa type (A) ground floor.
Fig 2.26 Distribution board in Villa type (A) First floor.
ยฒ
ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
ยฒ ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒยฒยฒยฒยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
CHAPTER 2 BUILDING WIRING CALCULATION
58
Fig 2.27 Distribution board in Villa type (A) Garage.
ยฒ
ยฒ
ยฒ
Fig 2.28 Riser diagram in Villa type (A).
ยฒ ยฒ
ยฒ ยฒ ยฒ
ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ
2.7.7 Villa type (B)
Ground Floor:
a) Lighting:
line Room Lux Area u n no. of lamps
lamps lamps
wattage power factor installed wattage lamp current LINE 1 LINE2 LINE 3 LINE4 LINE5
L1 - - -
12 100
1200 5.45 5.45
L2,L3 Reception 150 85.9 0.49 20 16.4 16 100 1 1600 7.27
3.64 3.64
L2 Terrace 150 20.52 0.49 20 3.9
3 100 1 300 1.36
1.36
L3
0.49 20 4 40 1 160 0.72
0.7
L4 Bathroom1 300 7 0.35 80 2.2 2 40 0.8 80 0.45
0.45
L4 Bathroom2 300 8 0.35 80 2.2 2 40 0.8 80 0.45
0.45
L4 Store 100 4.2 0.49 80 0.66 1 20 0.8 20 0.114
0.114
L4 kitchen 300 21.2 0.41 80 6.05 6 40 0.8 240 1.36
1.36
L4 kitchen balcony 100 3 0.49 80 0.47 1 20 0.8 20 0.114
0.114
L4 Entrance 200 12 0.49 20 3.06 3 100 1 300 1.36
1.36
L4 door lights - -
3 15 1 45 0.2
0.2
L5 M.bedroom 150 32.5 0.49 20
6.2 6 100 1 600 2.72
2.72
0.49 20 4 40 1 160 0.72
0.72
SUM 5.45 5 4.34 4.05 3.44
C.B 6.54 6 5.2 4.85 4.128
closest C.B 10 10 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
60
b) Normal & Power Sockets:
Line Type Calculations current C.B. rating M.C.B C.S.A
L1 Lighting - 5.45 - 10 3*2.5mmยฒ
L2 Lighting - 5 - 10 3*2.5mmยฒ
L3 Lighting - 4.34 - 10 3*2.5mmยฒ
L4 Lighting - 4.05 - 10 3*2.5mmยฒ
L5 Lighting - 3.44 - 10 3*2.5mmยฒ
L6 Normal socket 2+0.2(2*5) 4 4.8 10 3*2.5mmยฒ
L7 Normal socket 2+0.2(2*5) 4 4.8 10 3*2.5mmยฒ
L8 power plug 1*10 10 12 16 3*4mmยฒ
L9 power plug 1*10 10 12 16 3*4mmยฒ
L10 power plug 1*10 10 12 16 3*4mmยฒ
L11 power plug 1*10 10 12 16 3*4mmยฒ
L12 power plug 1*10 10 12 16 3*4mmยฒ
L13 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mmยฒ
L14 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mmยฒ
L15 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mmยฒ
L16 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mmยฒ
L17 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mmยฒ
L18 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mmยฒ
L19 Elevator 1.5*746/(220*0.9) 5.7 10 16 3*4mmยฒ
c) KVA calculation:
ฮฃ light =5.45+5+4.34+4.05+3.44= 22.28 A.
ฮฃ Normal sockets= (4ร2) =8 A.
ฮฃ Power sockets= (11.4ร4) + (7.6ร2) +0.5[10ร3] =75.8 A.
โด ๐ฐ๐๐๐๐=0.7[22.28+8+75.8] =74.256 A.
โด ๐ฒ๐ฝ๐จ๐๐๐๐๐๐ =74.256ร220=16.336 KVA.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =74.256
3= 24.752 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร10 mmยฒ.
First Floor:
a) Lighting:
Room Lux Area u n no. of lamps lamps lamps wattage power factor installed wattage lamp current LINE 1 LINE2 LINE 3
L1 M.bedroom 150 36.2 0.49 20 6.7 6 100 1 600 2.72 2.72
L1 Terrace 150 32.2 0.49 20 6.1
4 100 1 400 1.8 1.8
L1
0.49 20 4 40 1 160 0.72 0.72
L2 Bedroom1 150 30 0.49 20 5.7
4 100 1 400 1.8
1.8
L2
0.49 20 4 40 1 160 0.72
0.72
L2 Bedroom2 150 20.5 0.49 20 3.9 4 100 1 400 1.8
1.8
L2 Bathroom1 300 7 0.35 80 2.2 2 40 0.8 80 0.36
0.45
L3 Living 150 20.8 0.49 20 3.9 4 100 1 400 1.8
1.8
L3 corridor 100 5 0.49 20 0.7 2 40 1 80 0.36
0.36
L3 stairs area 100 10 0.49 20 1.4 1 100 1 100 0.45
0.45
L3 kitchen 300 6.3 0.41 20 2.1 2 100 1 200 0.9
0.9
L3 kitchen bar
3 15 1 45 0.2
0.2
L3 Dressing 150 11 0.49 80 0.8 1 20 0.8 20 0.1
0.1
L3 Bathroom2 300 7 0.35 80 2.2 2 40 0.8 80 0.36
0.36
L3 corridor 100 5 0.49 20 0.7 2 40 1 80 0.36
0.36
SUM 5.24 4.68 4.53
C.B 6.3 5.6 5.436
closest C.B 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
62
b) Normal & Power Sockets:
Line Type Calculations current column C.B C.S.A
L1 Lighting - 5.24 - 10 3*2.5mmยฒ
L2 Lighting - 4.68 - 10 3*2.5mmยฒ
L3 Lighting - 4.53 - 10 3*2.5mmยฒ
L4 Normal socket 2+0.2(2*6) 4.4 5.6 10 3*2.5mmยฒ
L5 Normal socket 2+0.2(2*5) 4 4.8 10 3*2.5mmยฒ
L6 power plug 1*10 10 12 16 3*4mmยฒ
L7 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mmยฒ
L8 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mmยฒ
L9 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mmยฒ
L10 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mmยฒ
L11 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mmยฒ
L12 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mmยฒ
L13 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mmยฒ
c) KVA calculation:
ฮฃ light =5.24+4.68+4.53= 14.42 A.
ฮฃ Normal sockets= 4.4+4 =8.4 A.
ฮฃ Power sockets=(11.4ร2) + (7.6ร2) + (8.5ร3) + (10) =73.5 A.
โด ๐ฐ๐๐๐๐=0.7[14.42+8.4+73.5] =67.424 A.
โด ๐ฒ๐ฝ๐จ๐ญ๐๐๐๐=67.424*220=15 KVA.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =67.424
3= 22.47 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร10 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
63
Roof Floor:
a) Lighting: line Room Lux Area u n
no. of lamps
lamps
lamps wattage
power factor
installed wattage
lamp current
LINE 1 LINE2
L2 Bedroom 150 26.4 0.49 20 5.6
4 100 1 400 1.8
1.8
L2
0.49 20 4 40 1 160 0.72
0.72
L2 Bathroom 300 7.5 0.35 80 2.2 2 40 0.8 80 0.36
0.36
L2 kitchen 300 3.5 0.49 20 1.12 1 100 1 100 0.45
0.45
L2 kitchen
bar 3 15 1 45 0.19
0.19
L2 Living 150 22 0.49 20 4.73
3 100 1 300 1.6
1.6
L1
0.49 20 4 40 1 160 0.72 0.72
L2 corridor 100 10 0.49 20 0.6 2 40 1 80 0.36
0.36
L1 Roof - -
9 100 1 900 4.09 4.09
SUM 4.81 5.12
C.B 5.77 6.144
closest C.B 10 10
b) Normal & Power Sockets:
Line Type Calculations current C.B. rating M.C.B C.S.A
L1 Lighting - 4.81 - 10 3*2.5mmยฒ
L2 Lighting - 5.12 - 10 3*2.5mmยฒ
L3 Normal socket 2+0.2(2*4) 3.6 4.2 10 3*2.5mmยฒ
L4 Normal socket 2+0.2(2*5) 4 4.8 10 3*2.5mmยฒ
L5 power plug 1*10 10 12 16 3*4mmยฒ
L6 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mmยฒ
L7 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mmยฒ
L8 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mmยฒ
c) KVA calculation:
ฮฃ light =4.81+5.12= 9.93 A.
ฮฃ Normal sockets= 3.6+4 =7.6 A.
ฮฃ Power sockets= 8.5+11.4+7.6+10 =37.5 A.
โด ๐ฐ๐๐๐๐=0.7[9.93+7.6+13.75] =38.521 A.
โด ๐ฒ๐ฝ๐จ๐ญ๐๐๐๐=38.521*220=8.4746 KVA.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =38.521
3= 12.84 ๐ด.
Then,
M.C.B=16 A (3 phase).
C.S.A =5ร6 mmยฒ.
CHAPTER 2 BUILDING WIRING CALCULATION
64
d) Riser calculation:
We will have 96 building of this type; we get the diversified KVA of apartment.
โด ๐ฒ๐ฝ๐จ๐๐๐๐๐ =0.6[8.5+15+16.5] =24 KVA.
โด ๐ฐ๐น๐๐๐๐ =24โ103
380 3 =36.46 A.
Then, Fuse=63 A (3 phase).
C.S.A =3ร25+25+25 mmยฒ.
Meter used = 80A Three phase meter.
CHAPTER 2 BUILDING WIRING CALCULATION
65
Fig 2.29 Distribution of lighting in Villa (B) Ground floor.
CHAPTER 2 BUILDING WIRING CALCULATION
66
Fig 2.30 Distribution of Sockets in Villa (B) Ground floor.
CHAPTER 2 BUILDING WIRING CALCULATION
67
Fig 2.31 Distribution of lighting in Villa (B) First floor.
Fig 2.32 Distribution of Sockets in Villa (B) First floor.
First Floor Plan
First Floor Plan
CHAPTER 2 BUILDING WIRING CALCULATION
68
Fig 2.33 Distribution board in Villa type (B) ground floor.
Fig 2.34 Distribution board in Villa type (B) First.
ยฒ
ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
ยฒ ยฒ ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒยฒ ยฒ
CHAPTER 2 BUILDING WIRING CALCULATION
69
Fig 2.35 Distribution board in Villa type (B) Roof.
Fig 2.36 Riser diagram in Villa type (B).
ยฒ ยฒ
ยฒ
ยฒ ยฒ
ยฒ
ยฒยฒยฒ
ยฒ
ยฒ
ยฒ
2.7.8 Villa type (C)
Basement Floor:
a) Lighting:
lines place room calculated
number of lamps
installed number of
lamps length width Lux Area U m ศ
lamps wattage
number of lamps
installed wattage
power factor
lamp current
line 1
line 2
line 3
line 4
1 1 entrance 6 6 18.835 3.36 50 63.2856 0.6 0.8 20 60 5.493542 360 1 1.63636 1.636
1 2 cinema 10 4 7.42 4.75 75 35.245 0.5 0.8 20 40 8.260547 160 1 0.72727 0.727
1
6
40
240 1 1.09091 1.091
2 3 living 6 6 4.69 4.12 150 19.3228 0.5 0.8 20 60 6.038375 360 1 1.63636
1.636
1 4 balcony 1 1 2.637 0.95 50 2.50515 0.5 0.8 20 40 0.39143 40 1 0.18182 0.182
2 5 big bathroom 9 10 4.69 5.32 300 24.9508 0.35 0.8 80 40 8.354063 400 1 1.81818
1.818
2 6 small bathroom 1 1 2 1.475 300 2.95 0.35 0.6 80 40 1.316964 40 0.8 0.22727
0.227
2
1
25
25 0.8 0.14205
0.142
2
0.7
0.7
2 7 bathroom extension
1 1 1.5 2.5 150 3.75 0.5 0.6 80 40 0.585938 40 0.8 0.22727
0.227
2
1
25
25 0.8 0.14205
0.142
2,3 8 stairs 1 6 6 9.113 3.6 50 32.8068 0.5 0.8 20 40 5.126063 240 1 1.09091
0.366 0.733
3 9 mosque
extension 3 3 1.8 3.7 150 6.66 0.5 0.8 20 40 3.121875 120 1 0.54545
0.546
3 10 mosque 8 8 6 3.7 200 22.2 0.5 0.8 80 20 6.9375 160 0.8 0.90909
0.909
3 11 corridor 1 1 1.68 1.23 50 2.0664 0.5 0.8 80 20 0.161438 20 0.8 0.11364
0.114
4 12 kitchen 8 8 4.5 6.5 300 29.25 0.41 0.8 80 40 8.360328 320 0.8 1.81818
1.818
3 13 door man room
bathroom 1 1 1.7 1.6 300 2.72 0.35 0.8 80 40 0.910714 40 0.8 0.22727
0.227
3
1
25 0.8 0.14205
0.142
3
0.7
0.7
3 14 door man room 5 4 3 2.875 120 43.64 0.5 0.6 20 100 8.728 400 1 1.81818
1.818
3 14
1
40
40 0.8 0.22727
0.227
4 15 servant room 4 4 4.13 3.65 120 15.0745 0.5 0.8 20 60 3.768625 240 1 1.09091
1.091
4 16 servant room
entrance 1 1 1.231 1.788 75 2.201028 0.5 0.8 80 40 0.128966 40 0.8 0.22727
0.227
4 17 servant room
bathroom 1 1 1.46 1.705 300 2.4893 0.35 0.6 80 40 1.111295 40 0.8 0.22727
0.227
4
1
25
25 0.8 0.14205
0.142
4
0.7
0.7
1 18 villa entrance 12 12 11.7 2.28 200 20.825 0.5 0.8 20 40 13.01563 480 1 2.18182 2.182
4 19 stairs 2 6 6 11.21 0.878 50 48.46 0.6 0.8 20 40 6.309896 240 1 1.09091
1.091
sum 5.818 5.259 5.416 5.296
C.B 10 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
71
b) Normal & Power Sockets:
Line Type number calculations current Column1 C.B C.S.A
line1 Lighting - - 5.818 - 10 3*2.5 mmยฒ
line2 Lighting - - 5.26 - 10 3*2.5 mmยฒ
line3 Lighting - - 5.416 - 10 3*2.5 mmยฒ
line4 Lighting - - 5.3 - 10 3*2.5 mmยฒ
line5 normal sockets 5 2+.2(2X4) 3.6 4.32 10 3*4 mmยฒ
line6 normal sockets 5 2+.2(2X4) 3.6 4.32 10 3*4 mmยฒ
line7 normal sockets 5 2+.2(2X4) 3.6 4.32 10 3*4 mmยฒ
line8 normal sockets 7 2+.2(2X6) 4.4 5.28 10 3*4 mmยฒ
line9 normal sockets 5 2+.2(2X4) 3.6 4.32 10 3*4 mmยฒ
line10 normal sockets 6 2+.2(2X5) 4 4.8 10 3*4 mmยฒ
line11 normal sockets 5 2+.2(2X4) 3.6 4.32 10 3*4 mmยฒ
line12 power socket 1 1x16 16 19.2 20 3*6 mmยฒ
line13 power socket 1 1x16 16 19.2 20 3*6 mmยฒ
line14 power socket 1 1x16 16 19.2 20 3*6 mmยฒ
line15 power socket 1 1x16 16 19.2 20 3*6 mmยฒ
line16 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line17 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line18 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line19 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line20 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line21 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line22 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
c) KVA calculation: ฮฃ light =5.818+5.26+5.416+5.3= 21.79 A.
ฮฃ Normal sockets=4.4+4+ (3.6ร5) =26.4 A.
ฮฃ Power sockets=0.3[(8.477ร4) + (7.57ร3) + (16ร4)] =33.64 A.
โด ๐ฐ๐๐๐๐=0.7[21.79+26.4+33.64] =57.267 A.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =57.267
3= 19.09 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร16 mmยฒ
Phase balance:
Phase A Phase B Phase C
light Line number L1,L2 L3 L4
current 11.0772 5.416 5.2964
Normal sockets Line number L(5,6) L(7,8) L(9,10,11)
current 7.2 8 11.2
Power sockets Line number L(12,16,17,19) L(13,14,20) L(15,18,21,22)
current 39.617 40.477 40.524
Sum
57.8942 53.893 57.0204
Ground Floor:
a) Lighting:
place room calculated number of
lamps
installed number of
lamps length width Lux Area U m ศ
lamps wattage
number of lamps
installed wattage
power factor
lamp current
LINE1 LINE2 LINE3
1 saloon 1 11 12 4.5 8.928 150 40.176 0.6 0.8 20 60 10.4625 720 1 3.272727 3.2727
2 reception 7 6 4.5 3.34 150 15.03 0.5 0.6 20 60 6.2625 360 1 1.636364 1.6363
3 saloon2 7 6 4.25 4.8 150 20.4 0.5 0.8 20 60 6.375 360 1 1.636364
1.6363
4 dining room
13 12 4.6 6.5 200 29.9 0.5 0.8 20 60 12.45833 720 1 3.272727
3.273
5 blank 6 6 4.5 4 150 18 0.5 0.8 20 60 5.625 360 1 1.636364
1.636
6 stairs 4 4 3.6 9 50 32.4 0.5 0.8 20 60 3.375 240 1 1.090909
1.09
7 passage 1 1 1 2 50 2 0.5 0.8 80 40 0.078125 40 0.8 0.227273
0.2273
8 bath ext. 1 1 1.72 1.85 150 3.182 0.5 0.8 80 40 0.372891 40 0.8 0.227273
0.2273
9 bath room 1 1 1.85 1.28 300 2.368 0.35 0.6 80 40 1.057143 40 0.8 0.227273
0.2273
1
0.35 0.6 80 25
25 0.8 0.142045
0.142
0.7
0.7
10 entrance 3 4 4 3.325 100 13.3 0.5 0.8 20 60 2.770833 240 1 1.090909
1.09
11 kitchen 5 6 4.5 4.16 300 18.72 0.5 0.8 80 40 4.3875 240 0.8 1.363636
1.363
12 back stairs 1 1 1.1 0.95 50 1.045 0.5 0.8 20 40 0.163281 40 1 0.181818
0.1818
13 balcony 5 6 11.5 2.3 50 26.45 0.5 0.8 20 40 4.132813 240 1 1.090909 1.09
SUM 5.999 5.795 5.999
C.B 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
73
b) Normal & Power Sockets:
Line Type number calculations current Column1 C.B C.S.A
line1 Lighting - - 5.99 - 10 3*2.5 mmยฒ
line2 Lighting - - 5.79 - 10 3*2.5 mmยฒ
line3 Lighting - - 5.99 - 10 3*2.5 mmยฒ
line4 normal sockets 6 2+.2(2X5) 4 4.8 10 3*4 mmยฒ
line5 normal sockets 6 2+.2(2X5) 4 4.8 10 3*4 mmยฒ
line6 normal sockets 5 2+.2(4x2) 3.6 4.32 10 3*4 mmยฒ
line7 normal sockets 7 2+.2(2X6) 4.4 5.28 10 3*4 mmยฒ
line8 normal sockets 5 2+.2(4x2) 3.6 4.32 10 3*4 mmยฒ
line9 normal sockets 6 2+.2(2X5) 4 4.8 10 3*4 mmยฒ
line10 power socket 1 1x16 16 19.2 20 3*6 mmยฒ
line11 power socket 1 1x16 16 19.2 20 3*6 mmยฒ
line12 power socket 1 1x16 16 19.2 20 3*6 mmยฒ
line13 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line14 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line15 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line16 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line17 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
c) KVA calculation: ฮฃ light =5.99+5.79+5.99= 17.77 A.
ฮฃ Normal sockets=4.4+ (4ร3) + (3.6ร2) =23.6 A.
ฮฃ Power sockets=0.5[(8.477ร4) + (7.57) + (16ร3)] =44.739 A.
โด ๐ฐ๐๐๐๐=0.7[17.77+23.6+44.739] =60.276 A.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =60.276
3= 20.092 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร16 mmยฒ
Phase balance:
Phase A Phase B Phase C
light Line number L1 _ L2,L3
current 5.99
11.78
Normal sockets Line number L(4,5) L(6,7) L(8,9)
current 8 8 7.6
Power sockets Line number L(10,14,15) L(11,16,17) L(12,13)
current 32.954 32.954 23.57
Sum
46.944 40.954 42.95
First Floor:
a) Lighting:
LINES place room calculated number of
lamps
installed number of lamps
length width Lux Area U m ศ lamps
wattage number of lamps
installed wattage
power factor
lamp current
line1 line2 line3 line4
1 1 main bed room 5 6 4.5 4.35 120 19.575 0.5 0.8 20 60 4.89375 360 1 1.636364 1.6363
1 2 balcony 0 1 1 2.36 0.5 50 1.18 0.5 0.6 20 40 0.245833 40 1 0.181818 0.1818
1 3 bed room living 7 6 3.9 4 150 15.6 0.5 0.6 20 60 6.5 360 1 1.636364 1.6363
1 4 balcony 1 1 1 4 1 50 4 0.5 0.8 20 40 0.625 40 1 0.181818 0.1818
1 5 bed room 1 5 6 4.5 4.4 120 19.8 0.5 0.8 20 60 4.95 360 1 1.636364 1.6363
1 6 balcony 2 1 1 2.36 0.5 50 1.18 0.5 0.8 20 40 0.184375 40 1 0.181818 0.1818
2 7 closet 1 2 2 2 3.12 250 6.24 0.5 0.8 80 40 1.21875 80 1 0.363636
0.3636
2 8 corridor1 1 1 1.26 5.643 50 7.11018 0.5 0.8 80 40 0.277741 40 0.8 0.227273
0.2273
2 9 bath room 1 4 4 3.52 3.12 300 10.9824 0.35 0.8 80 40 3.677143 160 0.8 0.909091
0.909
2
1
0.35 0.8 80 25
25 0.8 0.142045
0.142
2
0.7
0.7
2 10 closet 2 2 2 4.26 2 250 8.52 0.5 0.8 80 40 1.664063 80 0.8 0.454545
0.454
2 11 bathroom 2 3 3 3.18 2 300 6.36 0.35 0.8 80 40 2.129464 120 0.8 0.681818
0.6818
2
1
0.35 0.8 80 25
25 0.8 0.142045
0.142
2
0.7
0.7
2 12 corridor 2 1 1 1.2 2 50 2.4 0.5 0.8 80 40 0.09375 40 0.8 0.227273
0.2273
3,4 13 hall 9 8 4.6 9 100 41.4 0.5 0.8 20 60 8.625 480 1 2.181818
1.09 1.09
3 14 bed room 2 6 6 4.5 4.5 120 20.25 0.5 0.8 20 60 5.0625 360 1 1.636364
1.6363
3 15 balcony 3 1 1 2.36 0.5 50 1.18 0.5 0.8 20 40 0.184375 40 1 0.181818
0.1818
3 16 corridor 1 1 1.332 1.87 50 2.49084 0.5 0.8 80 40 0.097298 40 0.8 0.227273
0.2273
4 18 corridor 1 1 1.2652 2.01 50 2.543052 0.5 0.8 80 40 0.099338 40 0.8 0.227273
0.2273
4 19 bathroom 3 3 3 3.12 2.01 300 6.2712 0.35 0.8 80 40 2.099732 120 0.8 0.681818
0.6818
4
1
0.35 0.8 80 25
25 0.8 0.142045
0.142
4
0.7
0.7
4 21 bed room 3 6 6 4.578 4.63 120 21.19614 0.5 0.8 20 60 5.299035 360 1 1.636364
1.6363
4 22 balcony 3 1 1 2.36 0.5 50 1.18 0.5 0.8 20 40 0.184375 40 1 0.181818
0.1818
3 23 bathroom 4 3 3 3.12 2.01 300 6.2712 0.35 0.8 80 40 2.099732 120 0.8 0.681818
0.6818
3
1
0.35 0.8 80 25
25 0.8 0.142045
0.142
3
0.7
0.7
sum 5.4543 4.547 4.6592 4.6592
C.B 10 10 10 10
CHAPTER 2 BUILDING WIRING CALCULATION
75
b) Normal & Power Sockets:
Lines Type number calculations current Column1 C.B C.S.A
line1 Lighting - - 5.454 - 10 3*2.5 mmยฒ
line2 Lighting - - 4.547 - 10 3*2.5 mmยฒ
line3 Lighting - - 4.66 - 10 3*2.5 mmยฒ
line4 Lighting - - 4.66 - 10 3*2.5 mmยฒ
line5 normal sockets 6 2+.2(2X5) 4 4.8 10 3*4 mmยฒ
line6 normal sockets 7 2+.2(2X6) 4.4 5.28 10 3*4 mmยฒ
line7 normal sockets 7 2+.2(2X6) 4.4 5.28 10 3*4 mmยฒ
line8 normal sockets 5 2+.2(4x2) 3.6 4.32 10 3*4 mmยฒ
line9 normal sockets 5 2+.2(4x2) 3.6 4.32 10 3*4 mmยฒ
line10 normal sockets 7 2+.2(2X6) 4.4 5.28 10 3*4 mmยฒ
line11 normal sockets 7 2+.2(2X6) 4.4 5.28 10 3*4 mmยฒ
line12 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line13 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line14 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line15 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mmยฒ
line16 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line17 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line18 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line19 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
line20 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mmยฒ
d) KVA calculation: ฮฃ light =5.454+4.547+4.66+4.66= 19.27 A.
ฮฃ Normal sockets= (4.4ร4) + 4 + (3.6ร2) =28.8 A.
ฮฃ Power sockets=0.5[(8.477ร5) + (7.57ร4)] =32.094 A.
โด ๐ฐ๐๐๐๐=0.7[19.27+28.8+32.094] =56.1148 A.
โด ๐ฐ๐๐๐๐ ๐๐๐๐๐ =56.1148
3= 18.705 ๐ด.
Then,
M.C.B=32 A (3 phase).
C.S.A =5ร16 mmยฒ
Phase balance:
Phase A Phase B Phase C
light Line number L1,L2 L3 L4
current 10.001 4.66 4.66
Normal sockets Line number L(5,6,7) L(8) L(9,10,11)
current 12.8 3.6 12.4
Power sockets Line number L(12,16) L(13,14,17,18) L(15,19,20)
current 16.047 32.094 24.524
Sum
38.848 40.354 41.584
CHAPTER 2 BUILDING WIRING CALCULATION
76
Riser calculation:
We will have 23 building of this type; we get the diversified KVA of Villa. =0.7[57.267+60.276+56.1148] =121.56 A. =121.56ร220=26.74 KVA.
= 26 .74103
380 โ3 =40.627 A.
Then,
Fuse=63 A (3 phase). C.S.A =3ร35+35+35 mmยฒ. Meter used = 80A Three phase meter.
Fig 2.37 Distribution of lighting in Villa (C) Basement floor.
CHAPTER 2 BUILDING WIRING CALCULATION
77
Fig 2.38 Distribution of Sockets in Villa (C) Basement floor.
CHAPTER 2 BUILDING WIRING CALCULATION
78
Fig2.39 Distribution of Light in Villa (C) Ground floor.
CHAPTER 2 BUILDING WIRING CALCULATION
79
Fig 2.40 Distribution of Sockets in Villa (C) Ground floor
CHAPTER 2 BUILDING WIRING CALCULATION
80
Fig 2.41 Distribution of Light in Villa (C) First floor
CHAPTER 2 BUILDING WIRING CALCULATION
81
Fig 2.42 Distribution of Sockets in Villa (C) First floor
CHAPTER 2 BUILDING WIRING CALCULATION
82
Fig 2.43 Distribution board in Villa type (C) Basement.
Fig 2.44 Distribution board in Villa type (C) Ground Floor.
ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
ยฒยฒ ยฒ ยฒ
ยฒ
ยฒยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒยฒยฒยฒยฒยฒยฒ
ยฒ
ยฒ ยฒ
CHAPTER 2 BUILDING WIRING CALCULATION
83
Fig 2.45 Distribution board in Villa type (C) First floor.
Fig 2.46 Riser diagram in Villa type (C)
ยฒ
ยฒยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ ยฒ
ยฒ
ยฒ ยฒ ยฒ
Basement
ยฒ
ยฒ
ยฒ
LOW VOLATGE DISTUBUTION NETWORK
PLANNING
Chapter 3
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
84
Chapter 3
LOW VOLATGE DISTUBUTION NETWORK PLANNING
3.1 Introduction
In designing a system, distribution engineers may find a conflict between fulfilling
the requirements of the electrical considerations and the economical considerations in
the same time, so the good distribution system is the one than can fulfill both
considerations as much as possible in the same time.
An example of this conflict is the voltage drop on the feeders. For achieving good
performance of the system, voltage drop should be eliminated in order to have a flat
voltage profile. To achieve this we use cables of larger cross sectional area (c.s.a) in
order to have smaller resistance. On the other hand, the economical considerations in
some cases permits a certain range of voltage drop so as to fully use the used cables.
Yet if the conflict between electrical requirements and economical requirements can't
be solved; the priority is always for the electrical requirements since they represent
the safe operation which is the main aim of the distribution engineer.
Another example on the conflict between electrical and economical requirements
is to increase the service reliability for the critical loads, e.g. hospitals, computer and
control centers, critical industrial loads. To do this some back-up systems such as
emergency generators and/or batteries with automatic switching devices are used in
such places. These extra equipments cost more money, yet the reliability of the
service is more important than money in this case.
In their system design decisions of the secondary distribution network,
distribution engineers are primarily motivated by the considerations of economy,
coppers losses in the transformer and the secondary circuit, permissible voltage drops
and voltage flickers of the system. Of course, there are some other engineering and
economic factors affecting the selection of the distribution transformer and the
secondary configuration, such as permissible transformer loading, balanced phase
loads for the primary system, investment costs of the various secondary system
components, cost of labor, capital cost, inflation rates and other factors.
3.2 General Overview on the distribution system
The main components of the low voltage distribution network (secondary
distribution network):
3.2.1 Distribution Transformer
The first step of the low voltage distribution network is the distribution
transformer. At normal operation the transformer is loaded with 80% of its full load to
be able to withstand the loads of other transformer in case of fault. Distribution
transformers are put in either a kiosk in the street or in a room that is specially
designed for it. The transformer room is generally made of two compartments; the
RMU is placed in one of them and the transformer itself is placed in the other room.
This is to avoid any problems that might happen in the transformer when the switches
of the RMU are closed or opened. At normal operation the feeders are loaded with
70% of their full load to be able to withstand the other loads in case of fault; these
feeders are aluminum, because the probability of stealing copper cables is high.
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
85
3.2.2 Distribution Box (Pillar)
The second step in the network is the distribution box (pillar). The pillar can be
seen on the street. Itโs a short metal box. It is used to connect the distribution
transformer to the building box. The pillar is fed from two different feeders; one
comes from a distribution transformer and the other comes from another feeder on the
same transformer or another distribution transformer. When the pillar is fed from two
feeders from the same transformer and a fault occurs on this transformer; this
transformer goes out the network so this pillar will go out of the network too, but this
method is cheap and the maneuvering on network will be easy. On the other hand if
the pillar is fed from two feeders and each one comes from a different transformer, the
pillar has a supply in case a fault occurs on one of the two transformers, but this
method is expensive and the maneuvering on network will be more complicated. At
normal operation the pillar is loaded with 80% of its full load to be able to withstand
the loads of other pillar in case of fault. At normal operation the feeders are loaded
with 70% of their full load to be able to withstand the other loads in case of fault.
These feeders are aluminum, because the probability of stealing copper cables is high.
The pillar connection is shown in figure 3.1.
To Building Boxes
From Distribution Transformer
In Out
High Rupture
Fuse
Fig 3.1 Distribution box (Pillar)
In all these methods the pillar is connected to other pillars, and each feeder feeds a
group of pillars, there is a switch in mid way of two feeder to isolate the feeders from
each other and to balance the loading, but in case a fault occurs the faulty part is
isolated and the midway switch is closed to connect the healthy feeder to the loads on
the faulty feeder. These methods used to make sure that the continuity of supply is
achieved. This is shown in figure 3.2.
Piller Piller Piller
Piller Piller Piller
Fig 3.2 Feeding a group of pillars
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
86
3.2.3 Building Box (Coffree)
The third step on the network and the last one before the risers of houses is the
building box (sometimes called coffree). It used to connect pillars to risers of houses.
The coffree is fed from two different feeders; one comes from a pillar and the other
comes from another pillar, the coffree has a supply in case a fault occurs in one of the
two pillars, and the department of electricity can make maneuvering on network to
achieve the continuity of supply. This is shown in figure 3.3.
Coffree Coffree Coffree
Coffree Coffree Coffree
Piller
Piller
Fig 3.3 Feeding a Group of coffrees
The coffree is connected to the network by two feeders one goes in and the other
goes out. The fuse set is connected on the riser may be three single phase fuses to
prevent the failure in supply in case of the fuse of one phase is burnt , or one three
phase fuse if one phase suffer from over current the three phase supply will
disconnect. Riser is made of copper, because it has high conductivity, and it is safe
from stealing. The riser is shown in figure 3.4.
In Out
Riser
Fig 3.4 The Riser
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
87
3.3 Low Voltage Network (LVN) types
The part of the electric utility system which is between the distribution
transformers and the consumer's property (i.e. the circuit between the distribution
transformers and the pillars, and the circuit between the pillars and the consumer's
property) is called the Low Voltage Network (LVN). The types of LVN include:
1) Radial System
2) Open Loop (Ring) System
3.3.1 Radial LVN
For simplicity in both installation and operation, the radial system is the most
suitable one, and has low cost as well. A representative schematic diagram of such
LVN type is shown in figure 3.5.
Fig 3.5 Single line diagram of LVN
3.3.2 Open Loop (Ring) LVN
To obtain higher reliability of the network, open loop (ring) type system is chosen.
In such system any area has a main feeding system and an alternative on in case of
emergency. This is the method used in this project. This is shown in figure 3.6.
LV Side of
distribution
transformer
Transformer (1) Transformer (2)
n.o.
n.o.
n.o.
Piller
Buildings
Fig 3.6 Single line diagram of open loop LVN (two supply points)
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
88
We can notice that an open loop LVN can also be applied to a single supply
system as shown in figure 3.7. Yet this technique is not recommended because if a
fault occurs on the transformer; then all pillars connected to it will fail to deliver
power to their loads.
LV Side of
distribution
transformer
Transformer
n.o.
n.o.
Piller
Buildings
n.o.
Fig. 3.7 Single line diagram of open loop LVN (one-supply point)
3.4 General points to be considered in design
1. It is always preferred to put the distribution transformers in gardens as
possible; yet the environmental constraints should be also fulfilled.
2. For buildings of flats we usually use the diversification chart since the load
profile between buildings is not necessary to be the same so we can't take a
certain figure to be the diversity factor.
3. Diversification is used for any node that supplies more than one node; i.e. if
the pillar feeds more than one feeder then to get the load of the pillar we
consider diversification between these feeders. Same is done when considering
distribution transformers and pillars.
4. The locations of the transformers and pillars and the routes of the cables are
chosen so that:
The maximum voltage drop between any transformer and the furthest
consumer is 5% of the nominal voltage (220 V). to overcome this
voltage drop taps on the high tension side of the distribution
transformers are adjusted so that the consumer receives 220 V
The crossing between cables should be avoided as much as possible.
The routes of the cables should avoid street crossing as much as
possible so that when maintenance in feeders is done we don't need to
dig across the streets to get the cables out.
5. As we mentioned before the distribution boxes are connected in loops and so
does the coffree of the buildings. Thus if two coffrees or two boxes of
different loads are connected together then it is recommended that both have
the same c.s.a of feeders which suits the one with the larger load. This is very
important so that if a fault occurs on the box with larger load; the feeder of the
other box can withstand the overload safely.
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
89
6. Low voltage fuses ratings are as follows: 2, 4, 6, 8, 10, 16, 20, 25, 32, 35, 40,
50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000 and1250
Amperes according to ABB pocket book (switchgear manual), 8th edition.
7. Standard ratings of pillars are 50,100 KVA,150 KVA, and 200 KVA
8. Standard ratings of distribution transformers are 500 KVA and 1000 KVA.
9. Standard rating of street lighting pillars is 100A =22KVA
10. Additional 25% spare equipments should be used in the design; i.e. if the
design shows the need of 4 cables then a fifth cable is added as a spare. In this
project the extra equipments are not shown in the drawings but it is understood
that they are found.
11. In the secondary distribution networks the c.s.a of the cables used shouldn't be
less than (3ร70 + 35) mmยฒ or else the voltage drop will be severe and may be
more than the permissible ranges.
3.5 Planning of Distribution Network in the Residential Area:
A residential area for population of 35,291persons is divided into eight parts.
According to the population percentage occupying each type; our task is to:
1. Arrange their houses and service centers.
2. Arrange their supplying boxes so as to increase the reliability of the supply
and also its continuity.
3. Connect the boxes to their distribution transformers.
Calculations in this part depend on trial and error concept, and there are many
solutions. One of them is acceptable and the others are refused.
3.5.1 Calculation of Distribution Boxes (Pillars) and Feeders ratings:
For all the areas:
3.5.1.a Pillars:
I) Select the number of buildings to be fed by one pillar.
II) Calculate the number of flats per pillar.
III) Calculate the diversified KVA using the diversification chart.
IV) Pillar Loading = Diversified KVA ร Number of flats per pillar.
V) Select Pillar rating.
VI) Calculate number of pillars = ๐๐ข๐๐๐๐ ๐๐ ๐๐ข๐๐๐๐๐๐๐
๐๐ข๐๐๐๐ ๐๐ ๐๐๐๐๐๐ ๐๐๐ ๐๐ข๐๐๐๐๐๐๐
3.5.1.b Feeders (Pillar โ coffree)rating :
I) The feeder current Pillar Loading (KVA )ร103
3ร380รnumber of buildings per pillar=
II) Maximum feeder current = Feeder current
0.8
III) Enter tables of " Electro cable Egypt co. "
IV) Get the C.S.A for the feeder.
600/1000 volts -XLPE insulated multi cores cables with aluminum conductor
armored (SWA).
Pillar Calculations
Type Color Number
of Blocks KVA (Unit)
Buildings per Pillar
No. of flats per
pillar
Diversified KVA (Unit)
loading pillar
Pillar Rating (KVA)
C.S.A of feeder cables
mmยฒ
No. of pillars
Building A Green 24 15.9 2 24 7.2 172.8 200 3ร185+95 12
Building B Cyan 101 5 4 96 1.5 144 150 3ร120+70 26
Building C Pink 145 7.26 4 96 2 192 200 3ร185+95 37
Building D Orange 57 17.4 2 24 7.5 180 200 3ร185+95 28
Building E Yellow
70 8.5 8 80 1.6 128 150 3ร120+70 9
46 8.5 8 80 1.6 128 150 3ร120+70 6
Villa A Red 26 31.7 6 --- 19 114 150 3ร120+70 5
Villa B Blue 96 24 4 --- 16 64 100 3ร120+70 24
Villa C White 23 26.74 6 --- 15 90 100 3ร120+70 4
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
91
Pillar Fuse rating:
3.5.2 Calculation of Transformer and feeders ratings:
For all areas:
3.5.2.a Transformers :
I) Select the number of Pillars to be fed by one Transformer.
II) Calculate the number of flats per Transformer.
III) Calculate the diversified KVA using the diversification chart.
IV) Transformer Loading=(Diversified KVAร Number of flats per Transformer).
V) Select Transformer rating.
VI) Calculate number of Transformers = ๐๐ข๐๐๐๐ ๐๐ ๐๐๐๐๐๐๐
๐๐ข๐๐๐๐ ๐๐ ๐๐๐๐๐๐ ๐๐๐ ๐๐๐๐๐ .
3.5.2.b Feeders (Transformer โ Pillar ) :
I) The feeder current =Transformer loading (KVA )ร103
3ร380รnumber of Pillars per Trans ..
II) Maximum feeder current =Feeder current
0.8, & taking into consideration the tie
line (open loop) between pillars for more reliable system.
III) Enter tables of "Electro cable Egypt co."
IV) Get the C.S.A for the feeder.
600/1000 volts -XLPE insulated multi cores cables with aluminum conductor
armored (SWA).
Type Color Incoming Feeder
Fuse (A) Outgoing Feeder
Fuse (A)
Building A Green 400/630 160/250
Building B Cyan 400/630 160/250
Building C Pink 400/630 250/400
Building D Orange 400/630 160/250
Building E Yellow 250/400 100/160
160/250
Villa A Red 250/400 160/250
Villa B Blue 160/250 80/100
Villa C White 160/250 100/160
Transformer Calculations
Type Color Number of Buildings
KVA (Unit)
Flats per
building
Buildings per Pillar
pillars per
transf.
KVA diversified
(Unit) transf.
loading transf.
C.S.A of cables mmยฒ
No. of transf.
Transformer rating
Building A Green 24 15.9 12 2 3 5 360 2(3ร185+95) 4 500
Building B Cyan 101 5 24 4 6 1.5 864 2(3ร120+95) 5 1000
Building C Pink 145 7.26 24 4 4 2 768 2(3ร185+95) 10 1000
Building D Orange 57 17.4 12 2 6 5.2 748.8 2(3ร185+95) 5 1000
Building E Yellow
70 8.5 10 8 3 1.6 384 2(3ร120+95) 3 500
46 8.5 10 8 3 1.6 384 2(3ร120+95) 2 500
Villa A Red 26 31.7 ___ 6 5 13.5 405 2(3ร120+95) 1 500
Villa B Blue 96 24 ___ 4 8 12 384 3ร240+120 3 500
Villa C White 23 26.74 ___ 6 4 13 312 3ร240+120 1 500
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
93
3.5.3 Voltage drop Calculations :
For all areas:
3.5.3.a Between pillar and farthest coffree :
I) Calculate the feeder current =๐๐๐๐๐๐ ๐ฟ๐๐๐๐๐๐ (๐พ๐๐ด)ร103
3ร380ร๐๐ข๐๐๐๐ ๐๐ ๐๐๐๐๐๐๐ .
II) Measure longest distance between any pillar and coffree.
III) Enter tables of " Electro cable Egypt co. "
IV) Get the Voltage drop for the used C.S.A, (V/A/KM).
V) % V.D = ๐น๐๐๐๐๐ ๐๐ข๐๐๐๐๐ก ร๐๐๐ ๐ก๐๐๐๐ ร๐ ๐๐๐๐๐๐๐๐ ๐ฃ๐๐๐ก๐๐๐ ๐๐๐๐
220ร 100.
3.5.3.b Between Transformer and farthest Pillar :
I) The feeder current =Transformer loading (๐พ๐๐ด)ร103
3ร380ร๐๐ข๐๐๐๐ ๐๐ Pillars ๐๐๐ Trans .รNo .of circuits.
II) Measure longest distance between any Transformer and Pillar.
III) Enter tables of " Electro cable Egypt co. "
IV) Get the Voltage drop for the used C.S.A, (V/A/KM).
V) % V.D = ๐น๐๐๐๐๐ ๐๐ข๐๐๐๐๐ก ร๐๐๐ ๐ก๐๐๐๐ ร๐ ๐๐๐๐๐๐๐๐ ๐ฃ๐๐๐ก๐๐๐ ๐๐๐๐
220ร 100
โด Combined voltage drop = %V.D (Pillar-Coffree) +%V.D (Transformer-Pillar).
Transformer To Pillar Voltage Drop:
Type Color Length Pillar Diversified
(KVA) C.S.A of cables mmยฒ VD (V/A/KM) Transf.-Pillar (%VD)
Building A Green 62.88 120 2(3ร185+95) 0.424 1.104746757
Building B Cyan 120.88 144 2(3ร120+95) 0.604 3.630420924
Building C Pink 110.86 192 2(3ร185+95) 0.424 3.116341614
Building D Orange 117.4 124.8 2(3ร185+95) 0.424 2.145120229
Building E Yellow
150 128 2(3ร120+95) 0.604 4.004435169
140 128 2(3ร120+95) 0.604 3.737472824
Villa A Red 223.46 81 2(3ร120+95) 0.604 3.77506863
Villa B Blue 143.16 48 3ร240+120 0.344 1.632504792
Villa C White 114.01 78 3ร240+120 0.344 2.112657453
Pillar To coffree Voltage Drop
Type Color Length Coffree
Diversified(KVA)
C.S.A of cables mmยฒ VD (V/A/KM) Pillar-Coffree (%VD) Combined (%VD)
Building A Green 62.88 86.4 3ร185+95 0.424 1.59083533 2.695582086
Building B Cyan 29.54 36 3ร120+70 0.604 0.443591306 4.07401223
Building C Pink 36.6 48 3ร185+95 0.424 0.514424062 3.630765676
Building D Orange 4 90 3ร185+95 0.424 0.105414767 2.250534996
Building E Yellow
50 16 3ร120+70 0.604 0.333702931 4.338138099
55 16 3ร120+70 0.604 0.367073224 4.104546048
Villa A Red 58.96 19 3ร120+70 0.604 0.467284214 4.242352844
Villa B Blue 35 16 3ร120+70 0.604 0.233592051 1.866096844
Villa C White 98.03 15 3ร120+70 0.604 0.613366843 2.726024296
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
96
3.5.4 Short Circuit Current Calculations :
a) Calculate the impedance between (Pillar โ coffree):
i. Measure the shortest distance between any Pillar-Coffree.
ii. Get from the tables the C/C's Impedance for the used cables (mฮฉ/meter).
iii. Impedance = measured distance ร C/C's Impedance.
b) Calculate the impedance between (Pillar โ Transformer):
i. Measure the shortest distance between any Transformer-Pillar.
ii. Get from the tables the C/C's Impedance for the used cables (mฮฉ/meter).
iii. Impedance = measured distance ร C/C's Impedance
c) Calculate Transformer Impedance =4102
๐๐๐๐๐ ๐๐๐๐๐๐ ๐๐๐ก๐๐๐ร 6%
d) High Voltage network impedance = 0.319 mฮฉ
e) MLVSB Short Circuit Current (KA) =410
3ร ImpedanceTransformerH .V netwok
f) Pillar Short Circuit current (KA) = 410
3ร ImpedancePillarH .V netwok
g) Coffree S.C current (KA)= 410
3ร ImpedanceCoffreeH .V netwok
Pillar to Coffree Impedance
Type Area(color) Shortest distance between coffree &
pillar(m) C.S.A of cables mmยฒ
C/C'S Impedance (mฮฉ/meter)
Pillar to Coffree Impedance(mฮฉ)
Building A Green 20 3ร185+95 0.212 4.24
Building B Cyan 11.74 3ร120+70 0.325 3.8155
Building C Pink 13.48 3ร185+95 0.212 2.85776
Building D Orange 21 3ร185+95 0.212 4.452
Building E Yellow 12.34 3ร120+70 0.325 4.0105
Villa A Red 17 3ร120+70 0.325 5.525
Villa B Blue 10.2 3ร120+70 0.325 3.315
Villa C White 16 3ร120+70 0.325 5.2
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
98
Pillar to Transformer Impedance
Type Area(color) Shortest distance between
transformer& pillar(m) C.S.A of cables
mmยฒ C/C'S Impedance
(mฮฉ/meter) Pillar to Transformer
Impedance(mฮฉ)
Building A Green 10 2(3ร185+95) 0.212 1.06
Building B Cyan 17.74 2(3ร120+95) 0.325 2.88275
Building C Pink 10 2(3ร185+95) 0.212 1.06
Building D Orange 10.2 2(3ร185+95) 0.212 1.0812
Building E Yellow 8.33 2(3ร120+95) 0.325 1.353625
Villa A Red 80.5 2(3ร120+95) 0.325 13.08125
Villa B Blue 28.22 3ร240+120 0.163 4.59986
Villa C White 28.3 3ร240+120 0.163 4.6129
Transformer and H.V network impedance
Type Area(color) Transformer rating(KVA) Transformer Impedance(mฮฉ) H.V network Impedance (mฮฉ)
Building A Green 500 20.172 0.319
Building B Cyan 1000 10.086 0.319
Building C Pink 1000 10.086 0.319
Building D Orange 1000 10.086 0.319
Building E Yellow 500 20.172 0.319
Villa A Red 500 20.172 0.319
Villa B Blue 500 20.172 0.319
Villa C White 500 20.172 0.319
Short Circuit Currents
Type Area(color) MLVSB Short Circuit current
(KA) Pillar Short Circuit current
(KA) Coffree Short Circuit current
(KA)
Building A Green 11.552077 10.983881 9.17814782
Building B Cyan 22.7499866 17.814424 13.8402707
Building C Pink 22.7499866 20.64663 16.5270947
Building D Orange 22.7499866 20.608522 14.8519664
Building E Yellow 11.552077 10.836241 9.15538449
Villa A Red 11.552077 7.0508712 6.05448236
Villa B Blue 11.552077 9.4342566 8.33326681
Villa C White 11.552077 9.429356 7.81132496
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
101
3.6 EXAMPLE OF CALCULATIONS:
For Building B (Cyan Area):
3.6.1 Calculation of Distribution Boxes (Pillars) and Feeders ratings:
3.6.1.a Pillars :
1. Number of buildings to be fed the pillar = 4 buildings.
2. Number of flats per pillar = 96 flats.
3. The diversified KVA of flat using the diversification chart = 1.5 KVA.
4. Pillar Loading = 1.5 x 96 = 144 KVA.
5. Pillar rating = 150 KVA.
6. Number of pillars = 101
4 = 26 pillar.
3.6.1.b Feeders (Pillar โ coffree)rating :
1. The feeder current =144ร103
3ร380ร4=54.69 A.
2. Maximum feeder current = 54.69
0.8=68.304 A.
3. Entering tables of "Electro cable Egypt co."
4. The C.S.A for the feeder = 3ร120+70๐๐2.
600/1000 volts -XLPE insulated multi cores cables with aluminum conductor
armored (SWA).
3.6.2 Calculation of Transformer and feeders ratings:
3.6.2.a Transformers :
1. Number of Pillars to be fed by the Transformer =6 Pillars.
2. Number of flats per Transformer = 4ร6ร24=576 flats.
3. Diversified KVA using the diversification chart =1.5 KVA.
4. Transformer Loading=864 KVA.
5. Transformer rating = 1000 KVA.
6. Calculate number of Transformers = 26
6 = 5 transformers.
3.6.2.b Feeders (Transformer โ Pillar) :
1. The feeder current 864ร103
3ร380ร6==218.7 A
2. Maximum feeder current = 218.7
0.8=273.48 A
3. Entering tables of " Electro cable Egypt co. "
4. The C.S.A for the feeder = 2(3ร120+95) ๐๐2
600/1000 volts -XLPE insulated multi cores cables with aluminum conductor
armored (SWA).
CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING
102
3.6.3 Voltage drop Calculations:
3.6.3.a Between pillar and farthest coffree :
1. The feeder current =144ร103
3ร380ร4=54.69 A
2. longest distance between any pillar and coffree = 29.54 meter
3. Entering tables of " Electro cable Egypt co. "
4. The Voltage drop for the used C.S.A, (V/A/KM) = 0.604
5. % V.D = 54.69ร29.54ร0.604
220ร1000ร 100= 0.4435 %
3.6.3.b Between Transformer and farthest Pillar :
1. The feeder current =864ร103
3ร380ร6ร2=109.35 A
2. longest distance between any Transformer and Pillar =120.88 m
3. Enter tables of " Electro cable Egypt co. "
4. Get the Voltage drop for the used C.S.A, (V/A/KM).
5. % V.D = 109.35 ร120.88ร0.604
220ร1000ร 100= 3.629 %
โด Combined voltage drop = %V.D (Pillar-Coffree) +%V.D (Transformer-Pillar) = 4.0725 %
3.6.4 Short Circuit Current Calculations :
1. The impedance between (Pillar โ coffree)
a. The shortest distance between Pillar-Coffree=11.74m
b. The C/C's Impedance for the used cable=0.325(mฮฉ/meter).
c. Impedance = 11.74 ร 0.325=3.8155 mฮฉ.
2. The impedance between (Pillar โ Transformer)
a. The shortest distance between Transformer-Pillar=17.74 m.
b. Get from the tables the C/C's Impedance for the used
cables=0.325/2 (mฮฉ/meter).
c. Impedance = 17.74x0.1625=2.88275 mฮฉ.
3. Calculate Transformer Impedance =4102
1000ร 6%=10.086 mฮฉ.
4. High Voltage network impedance = 0.319 mฮฉ.
5. MLVSB Short Circuit Current (KA) =410
3ร(0.319+10.086)=22.75 KA.
6. Pillar Short Circuit current (KA) = 410
3ร 0.319+10.086+2.88 = 17.814 KA.
7. Coffree S.C current (KA) = 410
3ร(0.319+10.086+2.88+3.8155)= 13.84 KA.
MEDIUM VOLTAGE DISTRIBUTION
NETWORK
Chapter 4
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
103
Chapter 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
4.1 Introduction In the previous chapter, we studied the way to design the low voltage network
(secondary distribution network) in the power system, which begins with the
distribution transformers and ends with the center of loads.
In this chapter, weโll study the different ways to connect the medium voltage
network, which can also be named as primary distribution network which begins with
the high voltage distribution substations (for example 66/22 KV substation) which
step down the high voltage to a medium voltage which feeds the primary distribution
feeders.
4.2 General Overview on Medium Voltage Network (Primary
Distribution Network) Weโll begin our talk by a quick overview on the main components of the medium
voltage network (primary distribution network).
4.2.1 Substation
The medium voltage network begins with the substations; each substation contains
transformers that step down the high voltage coming from the generating source
through transmission lines to medium voltage coming out from these substations by
means of underground cables.
There are many ratings of stepping down substations, there are 66/11 KV
substations, 66/22 KV substations, and also there are substations of higher ratings that
began to appear in Egypt like the ones of rating 220/66/11 KV substations, and these
ones steps down the high voltage from 220 KV to 66 KV and steps from this high
voltage to a medium voltage of 11 KV.
Here in Egypt, the medium voltage is mainly 11 KV, but lately new networks of
22 KV are being installed for their better operation and the more advantages they
have.
The electric power is taken from these substations and delivered to medium
voltage distributors then to distribution transformers.
The cables used in the medium voltage network are 18/30 KV Aluminum cables,
for their lower cost and because the probability of stealing copper cables is high
compared to Aluminum cables.
In the figure 4.1 below, thereโs a substation that feeds a number of distributors in
a medium voltage network.
Fig 4.1 Substation feeding some distributors
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
104
4.2.2 Distributor (MVSG)
Itโ the second step in the medium voltage network, as the medium voltage (22
KV). We can consider it a sectionalized busbar supplied from two different 66/22 KV
transformers in the same substation or from different substations to assure the
continuity of supply in case of occurring of a fault in a cable between a transformer
and the distributor, this cable will be disconnected and the distributor will be supplied
from the other transformer and thus helps the reliability of this distributor.
The bar of the distributor will be fed from two different transformers through
medium voltage with-draw able circuit breakers. There is one with-draw able circuit
breaker on the bar called the bus coupler. This circuit breaker splits the bar in two
isolated parts each part is fed from one transformer. In case a fault occurs; this circuit
breaker will connect the isolated parts of the bar (after isolating the faulty feeder) to
feed all loads on the bar of the distributor. This system is known as two out of three
system (2/3 condition). The number of the outgoing feeders connected to the first part
of distributor bar is equal to the number of the outgoing feeders connected to the other
part. One feeder of the first part is connected to other one in the other part through
ring main feeder to make sure that the continuity of supply is achieved. In case of
fault; the ring main has a supply from one of the feeders coming from distributor. The
standard cross section area of the feeder coming from sub-station is (3x1x400) mmยฒ
(AL/XLPE/(18/30)KV/STA) for the two (24 MVA) distributors which is used in this
city , these feeders are always double, and each pair came from different sub-station
or from the same substation as mentioned above. The rule here in Egypt is that each
pair of cables can carry the whole load of the distributor alone in case of loss of the
other pair; that is the feeders are loaded by only 50% of their current carrying capacity
in the normal conditions (when the bus coupler is opened). Loading the cable with
only 50% of its capacity is of course a much exaggerated rule from the economical
point of view and we recommend that the feeder is loaded up to 70% of its capacity.
The outgoing of the two distributors has standard cables (3x240) mmยฒ (AL/XLPE/
(18/30)KV/STA). Each feeder in first part connected to another one on the second
part and forms an open loop. Number of transformers in each loop ranges between
816 transformers. A schematic diagram of the distributor is shown in figure 4.2.
Fig 4.2 The Distributor
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
105
4.2.3 Distribution Transformer
This transformer is equipped to the ring main feeder through two units of
switchgear (Load break switch, which can switch at light loads), then through a fused
load break switch (which is cheaper than the circuit breaker) to protect the
transformer from over current at fault time. This is known as Ring Main Unit
(R.M.U). Connection of the RMU's to the distributor is shown in figure 4.3.
Fig 4.3 Transformer supplied from RMU
A schematic diagram of the distribution transformer point for 22 KV systems with
all its equipment is given in figure 4.4.a
Fig 4.4.a schematic diagram of distribution transformer
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
106
A single line diagram of the distribution transformer point for 22 KV systems with
all its equipment is given in figure 4.4.b
Fig 4.4.b Single line diagram of a distribution transformer point
4.3 Medium Voltage Network Types 4.3.1 Medium voltage switchboard supply modes
4.3.1. a One bus bar, one supply source
It consists of 1 supply and 1 busbar, if a fault occurs that lead to unavailability of
supply, then the busbar will get out of service until the fault is repaired and the source
is available again.
Fig 4.5 1busbar, 1 supply source
22 KV
500KVA
22KV/380v
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
107
4.3.1.b One bus bar with no coupler, 2 supply sources Only one supply feeds the busbar at a time, while the other can be considered a
back up supply, and its advantage is that the busbar is supplied even if one of the
supplies is unavailable. But the disadvantage is in case of a fault on the busbar itself
which rarely occurs, so the outgoing feeders are no longer fed from either of the 2
sources.
Fig 4.6 1 bus bar with no coupler, 2 supply sources
4.3.1.c Two bus sections with coupler, two supply sources
This method is called two out of three operation (2/3 operation), which states that
only 2 of the 3 circuit breakers are closed and the third one is open.
The bus coupler circuit breaker is normally open and each section of the busbar is
fed from its source supply, but if there is a fault in one of the supply, this source is
disconnected and the bus coupler is connected, and both busbar sections are fed from
one source supply, until the faulted source supply is repaired.
The advantages of this method is the continuity of supply to all loads in case of a
fault on one of the sources, but if a fault occurs on one of the bus sections, then the
loads on this bus section are no more fed up from any of the 2 sources.
Fig 4.7 2 bus sections with bus coupler, 2 supply sources
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
108
4.3.1.d One bus bar with no coupler, three supply sources
The busbar is supplied from 2 parallel connected sources and third one is a back
up on case of loss of one of the two sources. The same problem occurs here which is
the unavailability of supplying the loads in case of a fault on the busbar, or in case of
its maintenance.
Fig 4.8 1 bus bar with no coupler, 3 supply sources
4.3.1.e Three bus sections with couplers, three supply sources
Each supply source feeds its own bus section and the bus couplers are kept
normally open. In case of loss of one of the supplies, the bus coupler associated to it is
closed and so the loads on this bus section are still supplied from another source. But
we suffer also from the same problem in case of a fault on one of the bus sections, and
then the loads connected to it are no more supplied by any of the supply sources.
Fig 4.9 3 bus sections with couplers, 3 supply sources
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
109
4.3.1.f Two bus bars, 2 connections per outgoing feeder, two supply sources
Each outgoing feeder is supplied by one of the two bus bars, depending on the
state of isolators which are associated with it and only one isolator per outgoing
feeder must be closed.
Fig 4.10 2 bus bars, 2 connections per outgoing feeder, 2 supply sources
4.3.1.g Two interconnected double bus bars
This arrangement is almost identical to the previous one. The advantage of this
arrangement appears from splitting up the double bus bars into two switchboards with
coupler (via CB1 and CB2) which provides greater operating flexibility and facilitates
the maneuver in the network. Another advantage is that each busbar feeds a smaller
number of feeders during normal operation. Of course the reliability increase so much
with this arrangement.
Fig 4.11 Interconnected double bus bars
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
110
4.3.1.h Duplex distribution system
In this arrangement each source can feed one or other of the bus bars via its two
draw out circuit breaker cubicle. For economical reasons, there is only one circuit
breaker for the two draw out cubicles which are installed alongside one another so it
is easy to move the circuit breaker from one cubicle to the other. Thus if source 1 is to
feed BB2, the circuit breaker is moved into the other cubicle associated with source 1.
The same principle is used for the outgoing feeders. Thus, there are two draw out
cubicles and only one circuit breaker associated with each outgoing feeder. Each
outgoing feeder can be fed by one or other of the bus bars depending on where the
circuit breaker is positioned.
Fig 4.12 Duplex distribution system
There are many advantages in this system such as:
If one source is lost, the other source provides the total power supply.
If a fault occurs on one of the bus bars or maintenance is carried out on it, the
coupler C.B is tripped and each circuit breaker is placed on the busbar in
service, so all the outgoing feeders are fed.
This arrangement is very reliable and the power supply continuity is high.
This arrangement is more economic since the amount of switch gear required
is reduced.
4.3.2 Medium voltage network structure
4.3.2.a Radial systems
It consists of a number of feeders getting out radial from a common source, and
the transformers are connected to the taps along the length of feeders.
The main disadvantage of this type is that if a fault occurs on one feeder, all the
loads connected to that feeder will no longer be supplied until this feeder is repaired,
and thus thereโs no continuity in the supply.
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
111
Fig 4.13 Radial system
4.3.2.b Loop (Ring) system
The main advantage of this system is the continuity of supply where two feeders
are taken from the same substation to the load. The ring system is a complete loop and
has an isolating switch.
Fig 4.14 Loop system
There are two main types of loop system which are:
I. Open loop
The main switchboard is fed by two sources with coupler.
The loop heads in A and B are fitted with circuit breakers.
Switchboards 1, 2 and 3 are fitted with switches.
During normal operation, the loop is open (on the figure it is normally
open at switchboard 2).
The switchboards can be fed by one or other of the sources.
Reconfiguration of the loop enables the supply to be restored upon
occurrence of a fault or loss of a source.
This reconfiguration causes a power cut of several seconds if an
automatic loop reconfiguration control has been installed. The cut lasts
dozens of minutes if the loop reconfiguration is carried out manually
by the operators.
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
112
Fig 4.15 Medium voltage open loop system
II. Closed loop
The main switchboard is fed by two sources with coupler.
All the loop switching devices are circuit breakers.
During normal operation, the loop is closed.
The protection system ensures against power cuts due to a fault.
This system is more efficient than the open loop since it avoids power
cuts.
On the other hand, it is more costly since it requires circuit breakers in
each switchboard instead of switches in case of open loop system. Also
the protection system is complex.
Fig 4.16 Medium voltage closed loop system
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
113
4.4 Calculation of the distribution point and sizing of the 22 KV
cables This city has transformers of 500 KVA and 1000 KVA rating.
There are two methods to calculate the total load of this city; either to consider the
rating of the transformers or to consider that each transformer is loaded by no more
than 80% of its full load. The second method is to be considered here since it is more
secure.
Weโll use two MVSG each up to 32MVA to supply all these residential loads,
commercial loads and the estimated loads. Each MVSG has three loops, two loops for
the actual loads and one loop for the estimated loads. The estimated loads are shown
in table 4.1 for the first MVSG and table 4.2 for the second MVSG.
Loads area building area estimated KVA/100mยฒ KVA
school 3 20500 12300 3 369
Institute of High 2 6550 3930 3 117.9
school 2 14600 8760 3 262.8
Institute of High 1 5900 3540 3 106.2
Headquarters collectivist 2711 1626.6 3 48.798
school 1 27000 16200 3 486
hotel 5550 3330 10 333
Commercial building 5 6850 4110 6 246.6
Commercial building 4 9200 5520 6 331.2
Commercial building 3 10700 6420 6 385.2
Commercial building 2 6600 3960 6 237.6
Commercial building 1 37400 22440 6 1346.4
club 45212 27127.2 5 1356.36
mosque3 1860 1116 3 33.48
mosque 4 245 147 3 4.41
sum 5664.948
Table 4.1
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
114
Loads area building area estimated KVA/100mยฒ KVA
Commercial building 6 24000 14400 6 864
Commercial building 7 19600 11760 6 705.6
mosque 1 1500 900 3 27
mosque 2 1150 690 3 20.7
House Decoration 617 370.2 5 18.51
clinic 590 354 5 17.7
school 25125 15075 3 452.25
hospital 23000 13800 12 1656
Administrative building 1 21227 12736.2 5 636.81
Administrative building2 20500 12300 5 615
Administrative building 3 11500 6900 5 345
Administrative building 4 71000 42600 5 2130
Service-based 5200 3120 3 93.6
sum 7582.17
Table 4.2
The MVSG is connected to a number of Ring Main Unit (R.M.U). Each R.M.U
consists of load break switches and fuses .The specifications of the used R.M.U are:
o Load Break Switches: Rated Voltage 24 kV
Basic Impulse Level 125 kV
Power Frequency Withstand Voltage 50 kV
Rated Current 600 A
Rated Short-time Withstand Current 1 sec 20 kA
Rated Making Withstand Current peak 50 kA
Inductive Breaking Current 10 A
Capacitive Breaking Current 40 A for Cable L.B.S.
o Fuse Ratings: Rated Voltage 24 KV
detaR Current 20 or 40 A
Rated Frequency 50 Hz
Rated Breaking Capacity โฅ 40 kA
The transformers connected to the first and the second MVSG are shown in fig 4.17
and fig 4.18 .The single line diagram of first and the second MVSG are shown in fig
4.19 and fig 4.20.
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
115
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
116
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
117
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
118
CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK
119
Calculation:
The maximum loads for one loop = 8 MVA
The loads of one of the two feeders of the loop = 4 MVA
So, the feeder current at normal operation = 322
4000 104.97 Amperes
And the maximum feeder current in case of fault = 5.0
97.104 209.94 Amperes
From tables of El Electro Cable Egypt Co.
Cables used have the following properties:
o Voltage Rating: 18/30 KV
o 18/30 KV Multi cores Aluminum conductors, XLPE Insulated, Steel tape
Armored and PVC Sheathed.
o C.S.A.: 22403 mm
o Conductor resistance = km/163.0
Calculation of the voltage drop in the primary distribution network (between the
distributor and the last transformer)
o V.D = 104.97ร0.163ร0.001ร1200m=20.53 volt
o Percentage V.D = 22000
53.20 ร 100 =0.0933 %
So, the voltage drop is neglected, since the operating voltage in the primary
distribution network is high (22 KV).
Some notes:
1-We will use what is called TYPICAL DISTRIBUTER ,each contains 12 cell, 4 cells
for input, 6 cells for output , one coupler & one riser, as shown in figure 4.20 .
2- We will use two distributors (MVSG) each up to 32MVA, the four input arms of
(3ร1ร400 mmยฒ) & the six output arms of 3ร240 mmยฒ.
66/22 KV SUBSTATION
Chapter 5
CHAPTER 5 66/22 KV SUBSTATION
120
Chapter 5
66/22 KV SUBSTATION
5.1 Introduction
In the previous chapter we have designed the medium voltage network
(MVSG), this network is supplied from 66/22 KV Substations which is our concern in
this chapter, these Substation consisting of one or more transformers (the number of
transformer is preferred to be even), with associated switchgear, protective gear and
control panels .the input power to the substation is from transmission lines.
Transformers substations equipment include bus bars, transformers, High
Voltage transmission lines and cables entrances, Medium Voltage feeders and
switchgear, either at the highest transmission voltage or at lower voltages has two
separate functions, to determine the paths of power flow, and a protective function
which may require it break the fault at the point or which it is situated switchgear
thus, include circuit breakers, isolating switches earthling switches potential and
current transformers, lighting arrestors , ...etc.
5.2 General Overview
At many places in the power system, it is desired to change some characteristics
of the electric power supplied like voltage, A.C. to D.C., frequency, improving power
factorโฆetc. and that is accomplished in suitable arrangement which we call
substation.
A substation is named according to its function in the power system, for example:
Transformer substation: in which the voltage is changed from one level to
another.
Switching Substation: in which an adequate method is used to switch on the
power lines.
Power Factor correction Substation: this contains condensers for improving
the power factor.
Frequency changer Substation: this is used to change the frequency of the
electric power supply to different frequencies required in different
applications.
Converting Substation: this converts A.C. to D.C. and vice versa which are
used in special applications in the power system.
Chapter 5 66/22 KV SUBSTATION
121
5.3 Substation Classifications
I. Step up substation
Itโs located after the generating source of electric power; the voltage is
stepped up in this substation before transmitting this electric power in the
transmission lines. And that helps to decrease the voltage drop in the transmission
lines as well as offering the probability to choose conductors of less c.s.a and less
cost as the current is decreased.
II. Bulk power substation
This substation receives power from the transmission system supplying a
very high voltage (132, 220 or 500 KV) and transformers it to sub-transmission
system having lower high voltage (66 KV).
III. Distribution substation
This substation received power from the sub-transmission system at high
voltage (66 KV) and transforms it to a medium voltage of (11 or 22 KV) to flow
in the primary feeder system.
5.4 Types of substation
I. Outdoor substation
This type is installed outdoor, and it needs more protection against pollution.
Itโs used in rural and urban areas where the cost of land is not high and itโs
available.
Its capital cost is less because of the less building needed in it.
Extension in this type of substation will be easy.
Bad weather conditions and rains may cause some problems.
It requires a large space.
Easy to identify fault location as the whole substation can be viewed.
Needs high maintenance and cleaning cost.
Chapter 5 66/22 KV SUBSTATION
122
II. Indoor substation
Itโs installed inside building and it has fewer problems against pollution.
Itโs used in cities and residential areas where the availability of land is low
and its cost is high
Its capital cost is high due to the higher cost of land and the cost of
buildings needed.
Extension in this type of substation will be very difficult.
It will have an easy operation.
It requires a small space.
Difficult to identify fault location.
Needs less maintenance and cleaning cost.
III. Gas Insulated substation (GIS)
Advantages of GIS
Due to insulation (sulpher hexafluoride SF6), the area of the GIS plan is
much less than the area of conventional type, hence it is very suitable for
the high population regions where the cost of land is very expensive. Also
the clearance between each unit and other will decrease hence the area
decreases.
There is a possible leakage of the gas, but its acceptable if occurs in range
1% for one kit and 5% for all kits in substation annually.
All parts of substation inside depth which is filled by SF6, and there is a
manometer for each distance to measure the pressure inside the ducts if it
decreases than that certain limit and steps out the range then it will close
the tripping coil circuit of C.V. hence, the C.B. is opened to protect the
system.
Yet the GIS type is more expensive than other types and needs continuous check that
the SF6 level is within the acceptable ranges.
Anyway, the following points are the requirements of a good substation:
It should be located at a proper site. It is better to be located at the load
center as much as possible.
Circuits are designed so that failure chances become small.
In case of fault; protection switchgear should work correctly.
Chapter 5 66/22 KV SUBSTATION
123
Fire extinguishers are installed.
Reactors to limit the short circuit current are used.
It should be easily operated and maintained.
It should involve minimum capital cost.
5.5 Substation layout
The layout of the substation is very important since there should be a Security of
Supply. In an ideal substation all circuits and equipment would be duplicated such
that following a fault, or during maintenance, a connection remains available.
Practically this is not feasible since the cost of implementing such a design is very
high. Methods have been adopted to achieve a compromise between complete security
of supply and capital investment. There are four categories of substation that give
varying securities of supply:
Category 1: No outage is necessary within the substation for either
maintenance or fault conditions.
Category 2: Short outage is necessary to transfer the load to an alternative
circuit for maintenance or fault conditions.
Category 3: Loss of a circuit or section of the substation due to fault or
maintenance.
Category 4: Loss of the entire substation due to fault or maintenance.
Different Layouts for Substations
I. Single Bus bar
The general schematic for such a substation is shown in the figure below.
Chapter 5 66/22 KV SUBSTATION
124
With this design, there is an ease of operation of the substation. This design also
places minimum reliance on signaling for satisfactory operation of protection.
Additionally there is the facility to support the economical operation of future feeder
bays.
Such a substation has the following characteristics.
Each circuit is protected by its own circuit breaker and hence plant outage
does not necessarily result in loss of supply.
A fault on the feeder or transformer circuit breaker causes loss of the
transformer and feeder circuit, one of which may be restored after isolating the
faulty circuit breaker.
A fault on the bus section circuit breaker causes complete shutdown of the
substation. All circuits may be restored after isolating the faulty circuit
breaker.
A bus bar fault causes loss of one transformer and one feeder. Maintenance of
one bus bar section or isolator will cause the temporary outage of two circuits.
Maintenance of a feeder or transformer circuit breaker involves loss of the
circuit.
Introduction of bypass isolators between bus bar and circuit isolator allows
circuit breaker maintenance facilities without loss of that circuit.
II. Mesh Substation
The general layout for a full mesh substation is shown in the schematic below.
Chapter 5 66/22 KV SUBSTATION
125
The characteristics of such a substation are as follows.
Operation of two circuit breakers is required to connect or disconnect a circuit,
and disconnection involves opening of a mesh.
Circuit breakers may be maintained without loss of supply or protection, and
no additional bypass facilities are required.
Bus bar faults will only cause the loss of one circuit breaker. Breaker faults
will involve the loss of a maximum of two circuits.
Generally, not more than twice as many outgoing circuits as in feeds are used
in order to rationalize circuit equipment load capabilities and ratings.
III. One and a half Circuit Breaker layout
The layout of a 1 1/2 circuit breaker substation is shown in the schematic below.
The reason that such a layout is known as a 1 1/2 circuit breaker is due to the fact that
in the design, there are 9 circuit breakers that are used to protect the 6 feeders. Thus, 1
1/2 circuit breakers protect 1 feeder. Some characteristics of this design are:
There is the additional cost of the circuit breakers together with the complex
arrangement.
It is possible to operate any one pair of circuits, or groups of pairs of circuits.
There is a very high security against the loss of supply.
Chapter 5 66/22 KV SUBSTATION
126
5.6 Substation Equipment
To do its task in a proper way, substations contain much equipment. The most
important and common equipment in the transformers substations are the following
1. Bus Bars
When a number of lines operating at the same voltage must be directly connected
electrically, bus bars are used as the common electrical point. Bus bars are rigid
aluminum or copper bars (generally of rectangular cross-section) and operate at
constant voltage and frequency. The incoming and outgoing lines in a substation are
connected to the bus bars. Bus bars receive power from incoming circuits and deliver
power to outgoing circuits.
There are many arrangements of bus bars in substations. Some of them are:
1- Simple single bus bar.
2- Sectionalized single bus bar system.
3- Double bus bar system.
4- Double sectionalized bus bar system.
While the system in (2) is commonly used for medium and low voltages (22KV and
less), the system in (4) is commonly used for high and extra high voltages (66 KV and
more).
2. Insulators
The porcelain insulators employed in the substations are of past and bushing
type. They serve as supports and insulations of the bus bar. A past insulator consists
of porcelain body, an iron cap and a flanged cast iron base.
Bushing insulators are used to pass the conductor through a wall or a tank
transformer. A bushing consists of porcelain shell body and upper and lower locating
washers used for fixing the position of the bus bar or rod in shell. For current rating
above 2 KA, the bushings are designed to allow the main bus bars to pass directly
through them.
3. Lightning Arrestors and Surge Arrestors
Lightning and surge arrestors are shunt resistors used to divert the lightning and
high voltage surges to earth and protect other equipment from H.V surges. They are
connected generally between phase conductor and ground. They are located where the
first equipment is seen from the incoming overhead line and also near transformer
terminals phase to ground. There are two types of surge arrestors; Gapped Arrestors
and Gapless Zinc-Oxide Arrestors.
Chapter 5 66/22 KV SUBSTATION
127
4. Isolators (disconnecting switch)
In substation, it is often desired to disconnect a part of the system for general
maintenance and repairs. This is accomplished by an disconnecting switches or
isolators. They are located at each side of the circuit breaker. They are disconnected
after tripping the C.B and closed before closing the C.B. That's why they don't have
any rating for current breaking or current making. From the common types of
isolators: center rotating horizontal swing isolators, vertical swing and pantograph
type isolator (for 420 KV). Isolators are interlocked with circuit breaker
5. Earthing switch
Its function is to discharge the trapped charges on the circuit to earth for safety.
They are mounted on the frame of isolators.
6. Current Transformer (CT)
It is used to step down the current for measurement, protection and control. The
need for a CT comes from the fact that the measuring, control and protection
instruments are designed for working at low ratings (usually 110V and 5A). The C.T
usually has three secondary coils; one for measuring, the 2nd
for protection and the 3rd
for controlling.
7. Voltage (potential) transformer (PT)
It is used to step down the voltage for measurement, protection and control. Its
location is at the feeder side of the circuit breaker. Its secondary voltage is usually 110
V.
8. Circuit Breaker (C.B)
There are two forms of open circuit breakers:
1. Dead Tank - circuit breaker compartment is at earth potential.
2. Live Tank - circuit breaker compartment is at line potential.
Circuit breakers are installed to perform the following duties:
Switching during normal and abnormal operating conditions
Interrupting short circuit currents.
C.Bs are located at both ends of every protective zone. Types of C.B depend on the
rated voltage and the medium of arc quenching. Among the types of C.B: SF6,
Vacuum, Air blast and minimum oil.
9. Power transformers
The power transformer used to step down the voltage from 66 KV to 22 KV.
The common connection of the power transformers is delta/star-earthed to trap the
zero sequence and third harmonic components and prevent them from reaching the
secondary side and thus the distribution networks.
Chapter 5 66/22 KV SUBSTATION
128
The rating of power transformers depends on the loads of the substation zone. In
general the most common used ratings for power transformers used in the distribution
substations are 25 and 35 MVA. Power transformers are usually oil filled. They have
two or three windings. They are provided with coolers.
Power transformers have tapped windings, which permit adjusting the output
voltage to broaden the range of primary voltage inputs. The transformer will have a
manual tap changer, which can be operated if the transformer is de-energized. An
automatic on load tap changing (OLTC) feature installed on a transformer provides
automatic tap changing under load, and normally varies the voltage to 10% of the
systemโs rated voltage in steps by changing tap connections using a motor-driven, tap-
changing switch. Sometimes voltage regulation is needed and the system
transformers. Voltage regulators are used to supply the control for the variations in
load.
Industry standards classify transformers as outdoor and indoor transformers. An
outdoor transformer is constructed of weather-resistant construction, suitable for
service without additional protection from the weather.
Several types of transformers are used in substation such as
a) Power Transformers
It is usual to provide some standby plant, since transformers require maintenance
in respect of their cooling system and tap changing equipment , so the operation of
two or three 3-phase transformers in parallel to carry a given load, with one similar
unit as standby, is usually providing 25 or 33 % spare plant capacity.
Power transformers are roughly by their means of cooling and by whether the
circulation of the insulating oil, which is also the cooling medium, takes place by
natural circulation, using the thermal head, or is forced by an external pump.
Power transformers are usually oil immersed with all three phases in one tank.
Auto transformers can offer advantage of smaller physical size and reduced losses.
The different classes of power transformers are:
O.N.: Oil immersed, natural cooling
O.B.: Oil immersed, air blast cooling
O.F.N.: Oil immersed, oil circulation forced
O.F.B.: Oil immersed, oil circulation forced, air blast cooling
Power transformers are usually the largest single item in a substation. For
economy of service roads, transformers are located on one side of a substation, and
the connection to switchgear is by bare conductors. Because of the large quantity of
oil, it is essential to take precaution against the spread of fire. Hence, the transformer
is usually located around a sump used to collect the excess oil.
Transformers that are located and a cell should be enclosed in a blast proof room.
Chapter 5 66/22 KV SUBSTATION
129
b) Auxiliary Transformers
To supply all services in substation such as lighting and control circuits.
c) Potential Transformers
It is used just for measurements and protection devices operate under low
voltage.
A Potential Transformer is basically a conventional constant-voltage
transformer with primary and secondary windings on a common core
connected in shunt or parallel to the power supply circuit to be measured or
controlled.
d) Current Transformers
Since measuring and protection devices cannot withstand high current, a current
transformer is used.
A Current Transformer is a constant-current transformer that reduces line
currents into values suitable for standard measuring devices such as ammeters
and watt meters and standard protective and control devices. It also isolates
these devices from line voltages. The primary winding is connected in series
with the circuit carrying the line current.
CT's may be accommodated in one of six manners:
Over Circuit Breaker bushings or in pedestals.
In separate post type housings.
Over moving bushings of some types of insulators.
Over power transformers of reactor bushings.
Over wall or roof bushings.
Over cables.
10. Marshalling Kiosk
They are used in the outdoor substations. They are used to mount both monitoring
instruments and control equipment and to provide access to various transducers.
Marshalling kiosks are located in the switchyard near every power transformer.
They are used in the indoor substations. They are used to house various measuring
instruments, control Instruments and protective relays. They are located in air-
conditioned building. Control cables are laid between switchyard equipment and these
panels.
Chapter 5 66/22 KV SUBSTATION
130
11. Shunt reactors
They are used with extra high voltage transmission lines to control the voltage
during low-load period by compensating the capacitance of the transmission line
during these periods.
12. Series reactors (current limiting reactors)
They are used to limit the short circuit currents and to limit current surges
associated with fluctuating loads.
13. DC Bus bars
The trip coils of all circuit breakers operate using a dc supply, thus we need dc bus
bar in the substation. This is achieved using two auxiliary transformers to step down
from 22 KV to 380 V. These transformers feed two rectifying units supplying two
chargers. These are charging two battery cells which are kept floating on the supply.
If the dc bus bars are de-energized for any reason, the batteries can fill in its place.
The 380 voltage supplies necessary lighting, air conditioning, motors for the cooling
fans and any other auxiliaries.
14. Station Earthing System
It is used to provide a low resistance earthing for doing the following tasks:
discharge currents from surge arrestors, overhead shielding and earthing
switches
for equipment body earthing
for safe touch potential and step potential in substation
for providing path for the neutral to ground currents for the earth fault
protection
5.7Earthing and Bonding
The function of an earthing and bonding system is to provide an earthing system
connection to which transformer neutrals or earthing impedances may be connected in
order to pass the maximum fault current. The earthing system also ensures that no
thermal or mechanical damage occurs on the equipment within the substation, thereby
resulting in safety to operation and maintenance personnel. The earthing system also
guarantees eqipotential bonding such that there are no dangerous potential gradients
developed in the substation.
Chapter 5 66/22 KV SUBSTATION
131
In designing the substation, three voltages have to be considered.
1. Touch Voltage: This is the difference in potential between the surface potential and
the potential at earthed equipment whilst a man is standing and touching the earthed
structure.
2. Step Voltage: This is the potential difference developed when a man bridges a
distance of 1m with his feet while not touching any other earthed equipment.
3. Mesh Voltage: This is the maximum touch voltage that is developed in the mesh of
the earthing grid.
Earthing Materials
1. Conductors: Bare copper conductor is usually used for the substation earthing
grid. The copper bars themselves usually have a cross-sectional area of 95 square
millimeters, and they are laid at a shallow depth of 0.25-0.5m, in 3-7m squares. In
addition to the buried potential earth grid, a separate above ground earthing ring is
usually provided, to which all metallic substation plant is bonded.
2. Connections: Connections to the grid and other earthing joints should not be
soldered because the heat generated during fault conditions could cause a soldered
joint to fail. Joints are usually bolted, and in this case, the face of the joints should be
tinned.
3. Earthing Rods: The earthing grid must be supplemented by earthing rods to assist
in the dissipation of earth fault currents and further reduce the overall substation
earthing resistance. These rods are usually made of solid copper, or copper clad steel.
4. Switchyard Fence Earthing: The switchyard fence earthing practices are possible
and are used by different utilities. These are:
(i) Extend the substation earth grid 0.5m-1.5m beyond the fence perimeter.
The fence is then bonded to the grid at regular intervals.
(ii) Place the fence beyond the perimeter of the switchyard earthing grid and
bond the fence to its own earthing rod system. This earthing rod system is
not coupled to the main substation earthing grid.
5. Neutral Grounding Equipment
They are either resistors or reactors. They are used to limit short circuit current
during ground faults. They are short time rated. They are connected between neutral
point and ground.
Chapter 5 66/22 KV SUBSTATION
132
5.8 Essential Civil Structure in outdoor substations
The following civil structures are necessary in a conventional outdoor substation:
Towers of incoming and outgoing transmission lines. These are generally
located outside the substation boundary, adjacent to the substation.
Towers (columns) and beams (gantries) for supporting strain conductors, and
flexible bus bars. These are used for mounting isolators, surge arrestors and
other equipment. Suitably; thereby eliminating additional separate
foundations.
Towers and gantries for supporting rigid tubular bus bars mounted on post
insulators. These insulators are supported on horizontal beams (gantries).
Support structures for post insulators which support the tubular rigid bus bars.
Support structures for mounting the substation equipment such as CTs, VTs,
isolators, circuit breakers, etc.
Supporting structures for auxiliaries such as cooling water system, fire
fighting system, etc.
The major items of the substation such as transformers and circuit breakers are
usually mounted on reinforced cement concrete plinths at ground level
5.9 Description of the Single Line Diagram and Layout for
the Present 66/22KV Substation
Figure which presents the single line diagram of the 66/22KV substation that
feeds the residential area in our project shows that the substation consists of a
sectionalized double bus bar system fed by six 66KV cables, two incoming from the
preceding substation in the 66KV ring and two are outgoing to the next substation in
the ring and remains two 66KV feeder cells as reserve.
The bus bar sections are coupled near a bus coupler consisting of a circuit breaker
and two isolating switches, together with four isolating switches dividing the bus bars
into four sections.
Four 66/22KV, 35MVA transformers are fed from the bus bars, and are connected
in parallel groups or each to a separate section of the bus bars. The transformer
connection circuit to the bus bar, as well as the feeder connection circuit, consists of a
66KV circuit breaker with two isolating switches towards the bus bars and one after
the circuit breaker on the other side.
Current and potential transformers are connected in the circuits for the objectives
of protection and measuring.
The transformers are connected via circuit breakers to the 22KV sectionalized bus
bar. This is cut into four sections coupled with four bus couplers. Outgoing 22KV
feeders come out of the 22KV bus bar sections, running outside the substation to feed
Chapter 5 66/22 KV SUBSTATION
133
the distribution points as well as some loops of distribution transformers and some big
consumers directly.
Two auxiliary transformers are fed from two different sections of the 22KV bus
bar. The ratings of these are 500KVA, 22/380KV in order to feed the substation
services; lighting, compressors, rectifiers to supply dc batteries, etc.
The figure while presents the layout of the substation on a plan at the ground level
indicates the substation arrangement. Four rooms for the four main transformers as
shown on one side of the 66KV-switchgear hall.
Meanwhile, the 22KV switchgear hall, the control room, the auxiliary
transformers room, as well as other service areas and the stairs are shown on the other
side. Above this several offices are arranged as well as the rest of services rooms,
which could be shown on anther plan at the level of the first floor.
The 66KV bus bars could be shown on a third plan at a higher level.
The figure which presents cross sections in two 66KV cells, one for a feeder
cell, the other is for a transformer cell. These side views describe clearly the circuit
connections of the 66KV feeder and the 66/22KV transformers to the 66KV bus bars.
They also show clearly the arrangement of the various apparatus in the circuit; the
circuit breakers, the isolating switches, the potential and current transformers.
Further, the single line diagram as well as the substation layout show lightning
arrestors to protect the substation from lightning surges, in the case of overhead
transmission lines feeding the substation.
Earthling switches are also connected to the 66KV and 22KV feeders to ground
these before carrying out maintenance or repair. Interlocks are provided between these
earthling switches and the respective circuit breakers.
POWER SYSTEM PROTECTION
Chapter 6
CHAPTER 6 POWER SYSTEM PROTECTION
134
Chapter 6
POWER SYSTEM PROTECTION
6.1 Introduction
There is a great importance of protection of power system and this importance
clearly appears though:
1. Ensuring the reliability and continuity of supply to different loads.
2. The large amount of capital investment in the power system justifies the
importance of protection.
So, we shall care for protecting every part in the power system to save ourselves,
to save the expensive components in the power system and to ensure the reliability of
supply in this system.
6.2 General Overview
Effect of short circuit currents on power system:
The fault current could be several thousands of amperes, which has a heating
effect and could result in melting of conductors or insulation failure.
Short circuits are associated with arcs which lead to fires.
Excessive currents lead to excessive forces between conductors, busbars,
transformers and coils.
When a fault occurs, the voltage drops to zero causing the nearest generating
station to go out of step.
In oil transformers, bubbles maybe formed which may lead to arc occurrence
and possibility of explosion.
As a result we should make a design for a good protective system which can
ensure a safe operation of the power system.
Requirements in any protection system:
1. Fast acting(speed): when a fault occurs, the protection system should clear that
fault as quickly as possible.
2. Sensitive: it should be sensitive to all kind of faults.
3. Reliability: the protection system should be reliable.
4. Selectivity (Discrimination): the protection system should be selective where
only faulty sections should be isolated.
5. Economical.
6.3 Types of faults in power systems
The faults in a power system can be classified into:
1. Symmetrical faults
2. Unsymmetrical faults
CHAPTER 6 POWER SYSTEM PROTECTION
135
6.3.1 Symmetrical faults
Fig 6.1 Symmetrical fault
It occurs when the three phases are connected together and to the ground.
Itโs the most severe fault (has maximum short circuit current).
Itโs the least probable type of fault (probability of happening is very small~5%).
Itโs used to determine the breaking (rupturing) capacity of circuit breakers.
6.3.2 Unsymmetrical faults
a) Line to Ground fault
Fig 6.2 Line to Ground fault
It occurs when a conductor of one phase touches the ground.
Itโs the most common type fault (probability of occurrence equals about 80 % of
faults).
It results from flashover on insulator string.
b) Line to Line fault
Fig 6.3 Line to Line fault
It occurs when conductor of different phases touch each others.
Probability of occurrence equals about~15% of faults.
c) Line to Line to Ground fault (Double Line to Ground fault)
CHAPTER 6 POWER SYSTEM PROTECTION
136
Fig 6.4 Double Line to Ground fault
This is similar to line to line fault but also involves a fault to earth.
Probability of happening is small.
6.4 Division of power systems into protective zones
6.4.1 Defining protective zone
Itโs a part of the power system protected by circuit breakers, such that in case of
fault occurrence inside it, only that faulted part is isolated and the remainder of the
system remains in normal operation.
6.4.2 Advantages of division of power system into protective zones
It can be used for circuit switching during normal operation.
It limits the damage caused during faults or overloads and minimizes its effect
on the remainder of the system.
And this is what is called Selectivity or Discrimination of the protection system.
Fig 6.5 Overlapping of protective zones
CHAPTER 6 POWER SYSTEM PROTECTION
137
6.5 Fuses
Fuses are the oldest and most simple protective devices. When the current
flowing through the fuse exceeds a predetermined value, the heat produced by the
current in the fusible link melts the link and interrupts the current. Since the current
must last long enough for the link to melt, fuses have inherently a time delay.
Fuses are relatively economical devices, they do not need any auxiliary devices
such as instrument transformers and relays, they are reliable, and available in a large
range of sizes. Their one disadvantage is that they are destroyed in the process of
opening the circuit, and then they must be replaced.
There are four quantities that are important for a particular fuse
application
I. Maximum Rated Voltage
Is the highest nominal system voltage at which the fuse can be used. The
voltage is given as an r.m.s and line to line value. The idea is that a blown fuse
should be able to withstand the system voltage.
II. Maximum Continuous Current
is the maximum r.m.s current the fuse should be able to carry indefinitely. This
current is given by an allowable temperature rise for the fuse, and therefore it also
depends on the ambient temperature.
III. Maximum Interrupting Current
is the largest current the fuse is capable of interrupting. This value should be higher
than the maximum possible fault current on this circuit.
IV. Time Response
This is given by the time-current characteristic. Medium voltage fuses are available
up to voltages of 36 kV for indoor use, and up to 161 kV for outdoor use.
Classification of fuses
I. Non-time delay fuses
The Non-time delay fuse consists of a single type of fusible element, called a short
circuit element. Normal overloads and current surges often cause nuisance openings
of this type of fuse.
Therefore, Non-time delay fuses should be used only in circuits with noninductive
loads such as circuit breaker back-up protection.
CHAPTER 6 POWER SYSTEM PROTECTION
138
II. Time delay fuses
The time delay fuse is constructed with two different types of fusible elements:
overload and short-circuit.
The overload element will interrupt all overload currents, and the short-circuit
element will open in response to short-circuit currents. The time delay fuse can be
applied in circuits subject to normal overloads and current surges (e.g., motors,
transformers, solenoids, etc.) without nuisance opening.
III. Current-limitation
Current-limiting fuses are so fast acting that they are able to open the circuit and
remove the short-circuit current well before it reaches peak value. Current-limiting
fuses โlimitโ the peak short-circuit current to a value less than that available at the
fault point and open in less than one-half cycle. To be effective, however, such fuses
must be operated in their current-limiting range.
IV. Medium-voltage fuses
There are two categories of the medium voltage fuses
Distribution fuse cutouts: developed for overhead distribution lines
Power fuses: developed for substations applications. Power fuses are
available at higher voltage and current ratings than the distribution fuse
cutouts.
They come in two types:
1. Current limiting fuses
2. Solid material fuses
V. High-voltage fuses
Some medium-voltage fuses and all high-voltage fuses are rated for outdoor fuse
use only.
VI. Current-limiting power fuses
Current-limiting power fuses are suitable for use on medium-voltage motor
controllers only.
6.6 Basic elements of protective switchgear
The main components of switchgear are:
1. Relays
2. Current Transformers (C.T.)
3. Potential (Voltage) Transformers (P.T. or V.T).
4. Circuit Breaker
CHAPTER 6 POWER SYSTEM PROTECTION
139
5. Tripping coil of circuit breaker
6. D.C. supply for energizing the tripping coil of circuit breaker
Fig 6.6 Main components of protective switchgear
6.7 Relay
Itโs a device which senses the abnormal condition of the power system, sends
signal to the circuit breaker to open the circuit. Relays canโt operate on power system
voltages and currents, therefore current transformers (C.T.) and potential transformers
(P.T.) are used.
6.7.1 Operation of Relays:
When the current in the main line exceeds a certain value, the current in R
increases.
The relay contact (R.C.) closes the circuit of the tripping coil (T.C.).
The T.C. opens the contacts of the circuit breaker which opens the circuit.
6.7.2 Development of Relays
6.7.2.a Electromechanical Relays
Most common type used.
Converts the electrical signal to a mechanical motion, closing or opening the
contacts of the relay.
Simple in operation.
Most widely used.
Operate by electromagnetic attraction or electromagnetic induction.
CHAPTER 6 POWER SYSTEM PROTECTION
140
Advantages:
Not expensive.
Simple in construction.
Easy in adjustment.
Disadvantages:
Maintenance required due to movements of relay parts.
6.7.2.b Static Relays
Involve no motion inside the relay.
Consist of electronic circuits (diodes, transistors, etcโฆ).
Advantages:
Lower power consumption therefore current and potential transformers are of
smaller ratings.
Mechanical problems are eliminated.
Disadvantages:
Very sensitive to voltage transients and spikes of small duration can damage
the semiconductor.
Sensitive to changes in the temperature.
6.7.2.c Digital Relays
Consist of digital circuits (AND, OR โฆgates).
Almost disappeared now.
6.7.2.d Programmable (Microprocessor) Relays
Can be programmed by certain software.
Has an interface with the user such that the setting of the relay can be changed.
Multi-function relays.
6.7.2.e Artificial Intelligence Relays
These relays employ an artificial intelligence (AI) technique for its operation.
Examples are: Neural Network, Fuzzy System, Expert Systems, and Genetic
Algorithms.
6.7.3 Classification of Relays
Relays are classified according to:
6.7.3.a Construction of the relay.
Solenoid type.
Attracted Armature type.
Balanced beam type.
Induction type.
CHAPTER 6 POWER SYSTEM PROTECTION
141
6.7.3.b Function of the relay:
Over-current relays
Over-voltage relays
Under-voltage relays
Directional power relays
Distance relays
Phase balance relays
6.7.3.c Time characteristics of the relay:
Instantaneous: complete operation occurs after a negligible small interval of
time.
Inverse time lag: time of operation is approximately inversely proportional to
the magnitude of current or other quantity causing operation.
Definite time lag: time of operation is independent on the magnitude of current
or other quantity causing the operation.
CHAPTER 6 POWER SYSTEM PROTECTION
142
6.7.4 Types of Electromechanical Relays
6.7.4.a Solenoid Type Relay
When a current passes in the coil, a force is exerted on the plunger.
The plunger moves and closes the relay contacts which energize the trip coil
of circuit breaker.
It has instantaneous time characteristics.
Relay Adjustment:
- Taps on the coil.
- Initial plunger position.
- 0i Minimum current to operate the relay.
Fig 6.7 Solenoid Type Relay
CHAPTER 6 POWER SYSTEM PROTECTION
143
6.7.4.b Balanced Beam Relay
It consists of a balance beam with a spring on one side and electromagnet on
the other side.
When the current is below the set value, the spring force and the force of
electromagnet are equal and the beam is balanced.
If the current exceeds the set value, the force of electromagnet overcomes the
spring force which closes the relay contacts and energizes the trip coil of
circuit breaker.
It has instantaneous time characteristics.
Relay Adjustment:
- By adjusting the air gap between the magnet and the iron piece.
- By using coil taps.
Fig 6.8 Balance Beam Relay
CHAPTER 6 POWER SYSTEM PROTECTION
144
6.7.4.c Attracted Armature Relay
The electromagnet attracts the armature which closes the relay contacts,
energizing the tripping coil of circuit breaker.
0i Minimum value of current after which the relay starts to operate.
It has inverse time characteristics.
Fig 6.9 Attracted Armature Relay
6.7.4.d Induction Relay
It is the most widely used relay because of their reliability.
It has more flexibility in coordination with other relays or fuses.
It has an inverse time characteristics.
Induction relays include the following types:
i. Induction Disc Type Relay
- A.C. current is supplied to the lower pole, by induction to the upper pole
directly or through a saturating transformer.
- The upper pole induces currents in the disc, and torque is produced by the
reaction between currents and flux from the lower pole.
- Current setting: by adjustment of the coil taps.
- Time setting: by adjustment of the contact travel.
- Breaking (Damping) magnet: its function is to give an eddy current breaking
effect to relay movement.
- This relay will operate only as long as the fault still exists.
CHAPTER 6 POWER SYSTEM PROTECTION
145
Fig 6.10 Induction Disc Type Relay
ii. Induction Disc Directional Power Relay
- The operating torque is produced by the interaction of magnetic fields derived
from both the voltage and current sources of the circuit it protects. A relay of
this type is essentially a wattmeter and the direction of torque set up in the
relay depends on the direction of current relative to the voltage. The voltage
coil is connected either directly or through a voltage transformer to the circuit
voltage source.
- Directional power relays are normally used for controlling the flow of power
in a circuit under normal load conditions or the reverse power protection of
synchronous machines. Figure 6.11 shows a schematic of this type of relay.
Fig 6.11 Induction Disc Directional Power Relay
CHAPTER 6 POWER SYSTEM PROTECTION
146
iii. Induction Type Three Phase Balance Relay
- Figure 6.12 shows the main constructional features of this relay. Contacts are
usually open and the spring makes the disc in a central position. For
appreciable unbalance of load on phases a, b, the contacts will close either due
to the right or left movement of the disc. A second disc on the same shaft is
mounted to provide means of response for any appreciable unbalance between
phases a, c.
Fig 6.12 Induction Type Three Phase Balance Relay
CHAPTER 6 POWER SYSTEM PROTECTION
147
iv. Impedance (Distance) Relay
- The balance beam has an operating coil on one side and a restraining coil on
the other side. The operating coil operates by the current I, whereas the
restraining coil operates by the voltage V.
- The balance point, i.e. the critical impedance value Zo could be adjusted by
current coil taps and by the air-gap adjustment. The balance point, i.e the
critical impedance value Zo is the impedance above which the relay will not
operate.
- The impedance relay is suitable for long lines. However, for short lines the
effect of a resistance may give false indication for the value of (Z) seen by the
relay. To overcome this, reactance relays are used. Reactance relays operate
when X= constant. Figure 6.13 shows the construction and the impedance
diagram of the impedance relay.
Fig 6.13 Impedance Relay
CHAPTER 6 POWER SYSTEM PROTECTION
148
6.8 Differential Protection of Power systems
If a fault occurs on any section of a transmission or distribution system, it is
essential that the faulty section should be rapidly isolated automatically from the
remainder of the network, hence preventing the damage resulting from the fault and to
localize the area of disturbance.
The ideal characteristics of switchgear are:-
It must be sufficiently sensitive to detect the presence of a fault.
It must discriminate between currents fed to faults in different sections in
order to prevent the isolation of healthy feeders.
It must operate in the shortest possible time.
It must be absolutely reliable in operation, simple and robust.
Protective system may be divided broadly into two broad classes: namely pilot
systems and pilotless systems. Pilot systems are those which employ pilot wires. In
general, pilot systems are more simple and reliable than pilotless systems, but the cost
of pilot wires limits their use on long transmission lines.
6.8.1 Merz-Price differential protection
This method of protection is based on the fact that the current entering one end of
a healthy feeder is equal to that leaving the other end. If a fault occurs, this equality
will not be maintained and the difference between the two currents is arranged to
operate relay which consequently trips the circuit breaker and hence the faulty section
is isolated.
There are two methods for applying the Merz price differential protection; namely
the circulating current method and the opposed voltage method.
Circulating current method
In the circulating current method, the current in the secondaries of the two
identical C.Ts will circulate in the pilot wires and no current will pass in the relay.
However, if an internal fault occurs, the difference in the currents in the secondaries
of the current transformers will operate the relay. Figure 6.14 shows the principle of
the circulating current method.
Fig. 6.14 Circulating Current method, Differential protection.
CHAPTER 6 POWER SYSTEM PROTECTION
149
Opposed voltage method :
In the opposed voltage method, the secondaries of the identical C.Ts are
connected in series together through relays by means of pilot wires. Under healthy
conditions, the secondary voltages of the C.Ts are in phase-opposition hence balance
each other and no current passes in the relay. If a fault occurs on the line, the currents
at both ends will no longer be equal and hence the induced e.m.f. in the C.Ts
secondaries will no longer balance, thus causing the flow of current in both relays.
Each relay closes its local circuit, energizing the trip coils which opens the C.B.
In order that the C.Bs shall balance as regard to both voltage and phase angle for
all primary current up to high current values, e.g. several thousands amperes, it is
necessary to prevent saturation of the iron core by providing a number of air-gaps in
the iron circuit. Figure 6.15 shows the schematic of this method.
Fig. 6.15 Opposed Voltage method, Differential protection
Advantages of Merz Price system
The operation is reliable.
The discrimination is ideal.
No potential transformers are required.
The operation is practically instantaneous.
The method is applicable to all kinds of systems, e.g. overhead lines,
underground cables, alternators, transformers, etc.
It operates for all types of faults whether to earth or between phases.
Disadvantages of the Merz Price system
The cost of the pilot wires is considerable especially for the long distance
transmission.
The possibility of operation by heavy through currents due to the capacitances
of the pilot wires. Such currents may induce voltage of about 1000 volts or
more in pilot wire circuit. Therefore, to prevent the resulting capacitance
current from operating the relays, the setting of the relay must be higher than
is desirable.
Frequent testing of the pilot circuit is necessary, since no warning would be
given for the break in the pilots, as these normally carry no current.
The C.Ts used should give exactly equal currents in their secondaries or else
the system operates in a wrong way. This is treated by using the biased beam
relay (sometimes called percentage differential relay)
CHAPTER 6 POWER SYSTEM PROTECTION
150
6.8.2 Biased Beam relay:
The disadvantage of the current differential protection is that current transformers
must give identical secondary currents; otherwise there will be current flowing
through the current relays for faults outside of the protected zone or even under
normal conditions. Sensitivity to the differential current due to the current transformer
errors is reduced by biased beam relays (sometimes called percentage differential
relays).
The biased beam relay is a circulating current method but with an additional
restraining coil which carries both circulating currents 1i and 2i Thus if the main
current is large, there is a comparatively large restraining force which cannot be
overcome by an error in the C.Ts.
The relay operates when the ratio of the difference ( 1i - 2i ) to the currents 1i or 2i
exceeds a certain minimum value which is adjustable by varying the number of turns
of the restraining coil (R.C). A schematic diagram of this method is given in figure
6.16
Fig. 6.16 Biased Beam relay
Advantages of this system
Since the relay operates on the percentage of the difference, settings down to
5% or 10% can be used without the risk of faulty tripping due to the through
currents. This means more sensitivity of the gear.
Ordinary C.Ts are used.
The pilot capacitance current flows through the restraining coil and will
actually produce a stabilizing effect.
CHAPTER 6 POWER SYSTEM PROTECTION
151
6.9 Applications:
6.9.1 Protection of Bus bars:
Differential Protection is applied to bus-zones, because of its great selectivity. A
simple method of bus-bar protection is by comparing the vector sum of currents
entering and leaving the bus zone.
Figure 6.17 shows bus-zone protection, two incoming supplies, based on the
circulating current method. Current will pass in the relay only in case of a fault on the
bus-bar .The same principle can be applied for any number of incoming supplies. The
relay current will be equal to zero as long as there is no fault on bus-bar zone.\
Fig. 6.17 Differential Protection of Bus bars
The following relays are installed in each busbar section of switchboard:
Under-voltage relay: A stationary under-voltage situation shall initiate tripping
of the connected motors.
Frequency relay: Input to Load Shedding System.
Arc detection relay: An arc detection system is installed either alone or in
combination with a current relay. Detection will sectionalize the busbar and
trip the incomer(s). This is not applied for single-phase air or gas (SF6
=Sulpher Hexa-florid) insulated switchboards.
CHAPTER 6 POWER SYSTEM PROTECTION
152
6.9.2 Graded type over current protection:
In these systems each relay is assigned a certain time setting. The most important
types of graded type over current protection are the following:
6.9.2.a Radial feeder protection
In the protection of radial feeders in series, relays are adjusted to have a
decreasing time setting with the increase of distance from the generating station. The
time to clear a fault (clearing time) is the sum of the times occupied in operating the
relays, energizing the tripping coils, moving the circuit breakerโs parts and
extinguishing the arc in the circuit breaker. Thus a fault on feeder between S/S 2 and
S/S 3 will results in the operation of relay R3 in a time of 1 second, as shown in figure
6.18
Fig. 6.18 Graded Type Over-current protection
(Radial feeder protection)
Disadvantages of this system
Not very sensitive.
To obtain proper discrimination, the minimum lag between operating times of
relays should not be more than 0.25 to 0.5 second. This limits the number of
relays in series to a maximum of six, since a short circuit should not be kept on
the generator for longer than 2 seconds.
The maximum fault current generally occurs at the generating end of the
feeder where the need of high clearing speed is the greatest, but actually the
time delay is maximum.
CHAPTER 6 POWER SYSTEM PROTECTION
153
6.9.2.b Protection of ring main:
The ring main system is an interconnection between a series of stations by means
of which provision is made for alternative routes of power supply without the
necessity for running feeders in parallel. If there is no reversal of power in any section
under normal operating conditions, then a series of directional relays with graded time
lags can be used. The grading is done in clock wise and anti-clockwise direction as
shown in figure 6.19
Each substation is protected by 2 relays, the one with the lower time setting being
directional and operates only for fault currents in the direction of arrow. With a fault
on any feeder section, this section only is isolated and all loads are still supplied
without any interruption of service.
Fig. 6.19 Graded Type Over-current protection.
(Ring Main system)
The disadvantage of this system is the same the previous one, plus the additional
one of using potential transformers that are necessary for the directional relays.
CHAPTER 6 POWER SYSTEM PROTECTION
154
6.9.3 Transformer protection:
Differential protection is applied for transformers. The difference in the current
magnitudes of the primary and the secondary windings of the main transformer is
corrected and taken into account by adjusting the turns ratio of the current
transformers.
For three phase transformers, the connection of the current transformers depends
on the connections of the main transformer.
Figure 6.20 shows a typical scheme for a Y/ฮ transformer. In order to account for
the phase shift of current in the secondary winding of the main transformer, the C.Ts
are connected as ฮ/Y, i.e. on the delta connected side of the main transformer, the
C.Ts are connected to star and vice versa. It can be proven that the currents in the
pilot wires are exactly in phase opposition. Hence their summation at the relay (R)
will be zero i.e no current will pass in the relay. Thus under normal conditions no
current will pass in the relays.
Fig. 6.20 Protection of Y/ฮ Transformer
For Y/Y power transformers, the C.Ts are connected as ฮ/ ฮ. For an internal fault,
the relays will operate and the tripping coils (T.C) at the both ends will be energized;
hence C.Bs at both ends will trip. This is shown in figure 6.21
Fig. 6.21 Protection of Y/Y Transformer
CHAPTER 6 POWER SYSTEM PROTECTION
155
The Bucholz relay
This relay is fitted to most oil โfilled transformers. It is fitted in the oil pipe
between the transformer tank and the oil conservator. Figure 6.22 shows a sketch of
the internal construction of the Bucholz relay.
Under healthy conditions, the relay is full of oil, and hence the mercury switch is
open, since the ball float is at its highest position. If there is any partial failure of the
insulation anywhere inside the transformer, gas will accumulate at the top of the relay.
Hence the ball float will drop down causing operation of the alarm mercury switch
M.S1 causing the alarm (visual or audible) to start.
If there is a short circuit inside the transformer, the explosion will instantly force
the oil against the plate P and thus closes the mercury switch which will trip the C.B.
Fig. 6.22 Bucholz Relay.
6.10 Circuit Breakers
Circuit breakers are used to control the flow of power in power systems and also as the disconnecting equipment when high faults occur on power systems. Circuit breakers then must be capable of performing switching operations on power systems under both, normal and short-circuit conditions .
Requirements put on every circuit breaker
- It must be a perfect conductor in the closed position
(Z = 0) .
- It must be a perfect insulator in the open position
(Z = infinity).
- It must be fast when closing. Current starts flowing before the contacts actually touch and slow closures could damage the contacts.
- It must be fast when opening but it must not extinguish current before its zero crossing and it must not produce over voltages.
B: Float Ball MS: mercury switch P: Plate
CHAPTER 6 POWER SYSTEM PROTECTION
156
Classification of Circuit Breakers:
Classification of circuit breakers in common use is done according to the medium that is used to interrupt the arc. Thus the breakers are classified as:
I. Air Circuit Breaker
Interruption of the circuit by using separation of contacts in air was sufficient, although this process drew arc and was damaging to the contacts of the switches. air blast breakers were also developed. The design followed two diverging paths. One was to design a single break breaker for a high voltage (up to 110 kV); the other was to connect several lower voltage (about 35 kV)
II. Oil Circuit Breaker
The mineral oil was held by a steel tank. there were made improvements to the plain break circuit breakers by providing arc and pressure control by enclosing the arcs inside arc pots
III. Sulpher Hexafluoride Circuit Breaker
Sulphur hexafluoride (SF6) was introduced as an interrupting medium. The initial tendency was to use the design of air blast breakers and the SF6 gas was blown under high pressure into the arc. The latest design is towards lower pressure SF6 breakers (these are called puffer type).
IV. Vacuum Circuit Breaker
The main problem was in joining the metal bellows enabling motion of the moving contact, and the ceramic container enclosing the contacts and the arc during breaker opening. The loss of vacuum resulted in explosions, and then in a great reluctance to accept the improved vacuum breakers.Vacuum breakers are now extensively used up to voltages of about 33 kV.
Circuit Breaker Ratings
1) Rated Voltage
Highest r.m.s voltage for which the circuit breaker is designed and is the upper limit for continuous operation.
2) Rated Current
The maximum r.m.s current, which the breaker is capable of carrying continuously without exceeding the given temperature, rise at the given ambient temperature.
3) Rated Frequency
Frequency at which the breaker is designed to operate (60 Hz in North America).
CHAPTER 6 POWER SYSTEM PROTECTION
157
4) Rated Interrupting current
Current at instant of contact separation. The interrupting current rating can be given as one of the following values.
5) Symmetrical Interrupting Current
RMS value of the A.C. component of the short circuit current the breaker is capable to interrupt.
6) Asymmetrical Interrupting Current
RMS value of the total short circuit current the breaker is capable to interrupt. This includes the dc and ac components.
7) Rated Making Current :
RMS value of the short circuit current on which the breaker can safely close at the rated voltage.
8) Rated Short Time Current
RMS value of current that the circuit breaker can carry in a fully closed position without damage for a specified short time interval. Normally given for 1s or 4s. These ratings are based on thermal limitations.
9) Rated Impulse Withstand Voltage BIL (Basic Insulation Level)
Maximum short duration impulse voltage tat the breaker can withstand. BIL is tested with a prescribed shape and duration of the test impulse voltage.
STREET LIGHTING
Chapter 7
CHAPTER 7 STREET LIGHTING
158
Chapter 7
STREET LIGHTING
7.1 Introduction Lighting is a vital rule to describe the importance of major and minor roads, which
constitute the lifelines of communication in the motorized world today.
For these roads, to fulfill their function properly, they must be made as safe as
technological and economic resources will permit .Lighting for guidance, lighting to
reveal all the features of roads and point up hazards. Lighting to aid perception and
provide clear visual information for both drivers and pedestrians.
So we can say that the basic purpose of street lighting is to promote safety and
convenience on the streets at night through adequate visibility, and to promote civic
progress. Statistics show that good street lighting installations results in:
Reduce traffic accidents
Respect the environment
7.2 Classification of factors affecting the design of street lighting 7.2.1 Area classification
7.2.1.a Commercial
That portion of a municipality in a business development where ordinarily there
are large numbers of pedestrians during business hours. This definition applies to
densely developed business areas outside, as well as within, the central part of a
municipality. The area contains land use, which attracts a relatively heavy volume of
nighttime vehicular and/or pedestrian traffic on a frequent basis.
7.2.1.b Intermediate
That portion of a municipality is often characterized by a moderately heavy
nighttime pedestrian activity such as in blocks having libraries, community recreation
centers, large apartment buildings or neighborhood retail stores.
7.2.1.c Residential
A residential development or a mixture of residential and commercial
establishments is characterized by a few pedestrians at night. This definition includes
areas with single family homes, town houses, and/or small apartment buildings.
7.2.2 Roadway classification
7.2.2.a Freeway
Itโs a divided major roadway with full control of access and with no crossings at
grade. This definition applies to toll as well as non-toll roads.
7.2.2.b Expressway
Itโs a divided major roadway for through traffic with partial control of access and
generally with interchanges at major crossroads. Expressways for non-commercial
traffic within parks and park-like areas are generally known as parkways.
11.2.2.c Arterial
The part of the roadway system that serves as the principal network for through
traffic flow. The routes connect areas of principal traffic generation and important
rural highways entering the city.
CHAPTER 7 STREET LIGHTING
159
7.2.2.e Local
Roadways used primarily for direct access to residential, commercial, industrial,
or other abutting property. They do not include roadways carrying through traffic.
Long local roadways will generally be divided into short sections by collector
roadway systems.
7.2.2.f Alleys
These are narrow public ways within a block, generally used for vehicular access
to the rear of abutting properties.
7.3 Street lighting arrangements 7.3.1 Two way traffic roads
There are four basic types of street lighting arrangements, which we can
summarize in the following points.
7.3.1.a Single sided
This type of arrangement, in which all luminaries are located on one side of the
road, is used only when the width of the road is equal to, or less than the mounting
height of the luminaries.
This is shown in fig 7.1.
Fig. 7.1 Single sided arrangement
7.3.1.b Staggered
This type of arrangement in which the luminaries are located on both sides of the
road in a staggered, or zigzag, arrangement is used mainly when the width of the road
is between 1 to 1.5 times the mounting height of the luminaries. This is shown in fig
7.2.
Fig. 7.2 Staggered arrangement
CHAPTER 7 STREET LIGHTING
160
7.3.1.c Opposite
This type of arrangement, with the luminaries located on both sides of the road
opposite to one another, is used mainly when the width of the road is greater than 1.5
times the mounting height of the luminaries.
Fig. 7.3 Opposite arrangement
7.3.1.d Span wire
This type of arrangement, with the luminaries suspended along the axis of the
road, is normally used for narrow roads that have buildings on both sides.
Fig. 7.4 Span wire arrangement
7.3.2 Curves
Curves of large radius (in the order of 300 m) can be treated as straight roads and
the luminaries can be sited in accordance with one of the schemes outlined above.
The locations of luminaries on curves of smaller radius, however, should be such
as to ensure both adequate road-surface luminance and effective visual guidance.
Where the width of the road is 1.5 m less than the mounting height, the luminaries
should be placed above the outside of the curve in a single sided arrangement.
For wider roads an opposite arrangement should be used since the staggered
arrangement gives visual guidance, and should therefore be avoided.
7.4 Street lighting design process The illumination design process involves the selection of the proper lighting
equipment and the establishment of the geometry of the system in order to provide the
most effective lighting system to satisfy the needs.
CHAPTER 7 STREET LIGHTING
161
7.4.1 The major steps of the design process are outlined as follows:
7.4.1.a Existing conditions
Determination of roadway facility and land use area classifications.
7.4.1.b Selection of illumination level
The recommended average intensity of horizontal illumination may be determined
based upon the classifications of roadway facility and area type .Table 7.1 shows the
recommended average maintained illumination (in foot candles).
The precise method of measuring light levels uses the foot-candle, the amount of
illumination provided by a single lumen distributed over a foot-square surface.
VEHICULAR
ROADWAY
CLASSIFICATION
AREA CLASSIFICATION
Commercial intermediate Residential
Freeway 0.6 0.6 0.6
Expressway 1.4 1.2 1
Major ( arterial ) 2 1.4 1
Local 0.9 0.6 0.4
Alley 0.6 0.4 0.4
Table 7.1 recommended average maintained illumination (in foot candles).
7.4.1.c System characteristics
Detailed calculations using selected lighting source types and sizes and luminaries
mounting heights and spacing locations are employed in order to determine the
average intensity of horizontal illumination. The uniformity of illumination is checked
by comparing the ratio of average maintained illumination to minimum maintained
illumination, commonly referred to as the uniformity ratio, with the recommended
criteria in order to determine optimal effectiveness of lighting system.
In our project ,we use two types of lighting poles of different mounting height .the
first one is 12 meter(mounting height) used for express way and arterial streets and
arranged usually in staggered or opposite sided system .the second type is used for
local streets and alleys and this type is a single sided arrangement.
e.g. the following figure illustrates one of the lighting poles.
Fig. 7.5 pole of 8m
CHAPTER 7 STREET LIGHTING
162
Checking illumination of local street, single sided arrangements
Calculation field test using DIAlux program
Valuation Field Roadway 1 & Sidewalk 1
Length: 30.000 m, Width: 14.000 m
Grid: 10 x 10 Points
Accompanying Street Elements: Roadway 1, Sidewalk 1.
Selected Lighting Class: CE5 (All lighting performance requirements are met).
Eav [lx] U0 (uniformity)
Calculated values: 27 0.4
Required values according to class: โฅ 7.5 โฅ 0.4
Fulfilled/Not fulfilled:
7.5 Types of lamps used in Street lighting We have to choose suitable kinds of lamps for different streets. The lamp must be
convenient for vehicles and pedestrians.
In internal streets, itโs recommended to use mercury lamps to give a white color,
with enough levels of average luminance to promote civic progress, and ensure
pedestrians safety.
On highways, where there are no pedestrians, we use high-pressure sodium lamps.
Its yellow light is suitable for such kinds of lighting, even in cloudy weather. The
human eye is very sensitive to yellow light, e.g. TPP- 250 watt, 33200Lm, 118
Lm/watt.
Article No.: Philips SRS427 1xSON-TPP250W P9
Luminary Luminous Flux: 33200 lm
Luminary Wattage: 274.0 W
Luminary classification according to CIE: 100
CIE flux code: 38 75 97 100 80
Fitting: 1 x SON-TPP250W/- (Correction Factor 1.000).
7.5.1 High pressure sodium lamps
Fig.7.8 HPS lamp Fig.7.7 250W luminary
The high-pressure sodium discharge lamp is a lamp providing the highest
efficiency in a light source with a good color rendition. Fig.
CHAPTER 7 STREET LIGHTING
163
Fig. 7.9 internal construction of HPS
The high-pressure sodium discharge is enclosed in an arc-tube envelope of high
temperature, alkali-vapor resisting high density, polycrystalline alumina.
The difference from the former low-pressure sodium lamp is that the sodium
pressure, with high volume loading, results in a well stabilized discharge and
maximum efficiency.
The high- pressure sodium discharge lamp has an initial efficacy in excess of 100
lumens per watt. Median lamp lifetime is in order of 6000 hours but may be expected
to improve with improved construction techniques.
High efficiency with acceptable color and a small, high brightness source with
low ultraviolet radiation make the high-pressure sodium lamp attractive as a lighting
source for street, roadway and area lighting.
Spectrum of High Pressure Sodium Lamp Spectrum of high pressure sodium lamp. The yellow-red band on the left is the atomic
sodium D-line emission; the turquoise line is a sodium line which is otherwise quite
weak in a low pressure discharge, but become intense in a high pressure discharge.
Most of the other green, blue and violet lines arise from mercury.
Fig. 7.10 spectrum of HPS lamp
7.5.2 Low pressure sodium lamps
Fig. 7.11 LPS of 35W Fig. 7.12 running LPS
CHAPTER 7 STREET LIGHTING
164
This type of lamp has special purposes because they give very strong light under
small power. This type of lamps has dark yellow light and is used in tunnels and
closed public places. They also have relatively long life.
7.5.3 Metal halide lamps
This is a very special purpose lamp it has special advantage that it can response
very fast to electric power when turning on and very slow when turning off, i.e. it
turns on quickly and turn off slowly. Thus this type of lamps could be used in medical
operation room and flood lighting. e.g. HSLL-BW-400, 400 watt, 2300 lm/watt.
Metal halide lamps operate under high pressure and temperature, and require
special fixtures to operate safely It gives a bright white light thus it could be used in
illumination of open places such as large stadiums since this type of lamps have
strong glass, they should be put when they should be hanged over large arm poles.
Fig. 7.13 metal halide in stadium Fig. 7.14 metal halide in baseball Stadium
7.5.4 Mercury lamps
There are several types of mercury lamps such as high-pressure, low pressure and
compound mercury lamps. This type has special applications.
Fig. 7.15
A mercury-vapor lamp is a gas discharge lamp that uses mercury in an excited
state to produce light. The arc discharge is generally confined to a small fused quartz
arc tube mounted within a larger borosilicate glass bulb. The outer bulb may be clear
or coated with a phosphor; in either case, the outer bulb provides thermal insulation,
CHAPTER 7 STREET LIGHTING
165
protection from ultraviolet radiation, and a convenient mounting for the fused quartz
arc tube.
Mercury vapor lamps (and their relatives) are often used because they are relatively
efficient. Phosphor coated bulbs offer better color rendition than either high- or low-
pressure sodium vapor lamps. Mercury vapor lamps also offer a very long lifetime, as
well as intense lighting for several special purpose applications.
7.6 Methods of switching of lamps There are various methods, some of which are:
a) Photo cell
b) Control switch
c) Timer
7.7 Street lighting system The distribution lighting network consists of:
1. Lighting distribution box
2. Poles
3. Lighting luminaries
4. Cables
7.7.1 Lighting distribution box (LDB)
The LDB is a pad-mounted-explosion proof type provided with the following
equipment and devices.
a) One incoming C.B.
b) Four outgoing circuit breakers.
c) One KWH meter
d) Automatic contactor (photocell or timer)
The lighting distribution box is shown in fig 7.16.
Fig 7.16 Lighting Distribution Box
CHAPTER 7 STREET LIGHTING
166
7.7.2 Poles
There is a wide range of street lighting poles which can be classified according to
their height (15m, 12m, 10m, 8m, โฆโฆ3m) or according to their type (stepped,
octagonal, โฆ.., or round).
The poles of 12m height are used in lighting system for most of streets, and the
poles of 3m height are mainly used for gardens lighting. For Alleys and Local streets,
poles of 8 m are used to fulfill the required lighting characteristics.
Fig 7.17 shows the main construction of poles used in street lighting.
(1) Mounting Height (Height above working plane). (2) Overhang. (3) Boom Angle. (4) Boom Length.
Fig 7.17 Construction of street lighting poles
The total pole heights depend on the method of installation. The manufacturer
should increase the pole height by at least 1-5m if itโs directly mounted in soil or in
concrete. Fig 7.18 shows the recommended type of lighting poles (12m high)
Fig 7.18 The 12m high pole used in street lighting
CHAPTER 7 STREET LIGHTING
167
The 3m poles are of decorative or round types. This is shown in fig 7.19.
Fig 7.19 The 3m high poles used in gardens
Each pole should be provided with a door opening for cable connection at a height
not less than 80 cm from ground level.
7.7.3 Lighting luminaries
The street lighting designed here to use several types of luminaries. Their type of
lamps is:
250, 400 watt high pressure sodium vapor lamps.
160 watt mercury lamps.
Different shapes of luminaries are shown in fig 7.20.
This type used in our project.
250W HPS street lamp
CHAPTER 7 STREET LIGHTING
168
400W HPS street lamp
160W mercury vapor lamp
Fig 7.20 Different shapes of luminaries
7.7.4 Cables
I. Cables of aluminum types should be used to connect the low voltage side of
distribution transformer to the lighting distribution box (LDB), and the cross
sectional area of cables is chosen according to the lighting loads and the rating
of the lighting distribution box (LDB).
II. Types of Aluminum conductors are :
A. ALL Aluminum Alloy Conductor(AAAC)
B. Aluminum Conductor Steel Reinforced(ACSR)
C. Aluminum Alloy Conductor Steel Reinforced(AACSR)
D. Aerially bunched cables(ABC)
III. Available cross section areas of aluminum cables are (4ร25) mm2
or
(4ร16mm2).
IV. In our project design, the selected cable is AAAC with cross section area in is
(4ร25mm2).
V. Cables of 2 mmยฒ copper are used to connect power cables and luminaries.
The following figures show some types of Aluminum Conductors
CHAPTER 7 STREET LIGHTING
169
Fig. 7.21 AAAC Fig. 7.22 Abc cables
Fig. 7.23 ACSR for O.H.T.L
7.8 Lighting control and Wiring system 7.8.1 On-off control
Luminaries for dusk to dawn operation will normally be controlled by a
photoelectric cell installed on each luminary, however, central control may be more
economical for luminaries having fixed hours of operation.
An automatic system using a time switch with an astronomical dial or a manual
on-off control will be used for such cases.
7.8.2 Type of system
Multiple wiring systems will be installed, except for extensions to existing series
systems or for long access roads where voltage drops exceeding that permitted for
multiple lighting systems would occur.
Circuits for multiple lighting will be designed to utilize the highest low-voltage
level appropriate for the installation in order to keep wire sizes and voltage drops to a
minimum.
Lamps will be connected phase-to-neutral rather than phase-to-phase. Where
practically, units will be connected to transformers, which serve other loads. Also
protection and disconnection of lighting circuits will be provided.
7.8.3 Grounding
All lighting circuits will include an equipment grounding conductor. The
equipment grounding conductor may be any conductor approved by the NEC, and
will be bonded to the non-current-carrying metal parts of each lighting standard and
luminary.
CHAPTER 7 STREET LIGHTING
170
7.9 Design of the street lighting scheme using DIAlux program:
1. We specify the width, we have in our plan.
2. Open red DIALux program
3. Select DIALux wizards
4. Select quick street planning
5. In DIALux street wizard :click next
6. Enter the various street elements and their properties such as
a. Width of side walk
b. Width of bicycle lane
c. Roadway width
d. Number of lanes
7. Enter the various valuation fields for the streets .select a lighting class for
Each valuation field in order to define the photometric requirements of the
Street.
Example:
a) Open lighting class selection: click next
b) Enter the typical speed of the main user type. e.g. Medium(between 30
&60 km/hr)
c) Enter the main user type & the other permitted user types.
d) Enter the main weather type. e.g. dry
e) Enter the type and frequency of the interchanges.
f) Enter the number of vehicles that pass a defined point in a defined
time(determination of traffic flow)
g) Enter whether or not to take a conflict zone into consideration, conflict
zones are zones that are also used by other traffic participants.
h) Enter the complexity of the field of version of the traffic participants
i) Enter the navigational difficulty of the traffic participants.
j) Enter the estimated luminance level of the environment.
e.g. this is a lighting class ME3a
8. Select valuation field for the optimization.
9. Select a luminary for the arrangement from your favorite catalogue
10. Specify which parameters of the luminary arrangement are allowed to vary at
which intervals.
a) Parameters that may be varied for the optimization.
b) Fixed parameters for the optimization.
c) Arrangement type(single sided, staggered or opposite sided)
11. Select suitable distance between luminaries that satisfy required illumination.
SYSTEM GROUNDING
Chapter 8
CHAPTER 8 SYSTEM GROUNDING
171
CHAPTER 8
SYSTEM GROUNDING
8.1.The importance of Earthing
Earthing or grounding is done for safety of equipment and human beings
(including all animals and plants).
In electricity supply systems, an earthing system defines the electrical potential of
theconductors relative to that of the Earth's conductive surface. The choice of earthing
system has implications for the safety and electromagnetic compatibility of the power
supply. Note that regulations for earthing (grounding) systems vary considerably
among different countries.
A protective earth (PE) connection ensures that all exposed conductive surfaces are
at the same electrical potential as the surface of the Earth, to avoid the risk of
electrical shock if a person touches a device in which an insulation fault has occurred.
It ensures that in the case of an insulation fault (a "short circuit"), a very high current
flows, which will trigger an overcurrent protection device (fuse, circuit breaker) that
disconnects the power supply.
A functional earth connection serves a purpose other than providing protection
against electrical shock. In contrast to a protective earth connection, a functional earth
connection may carry a current during the normal operation of a device. Functional
earth connections may be required by devices such as surge suppression and
electromagnetic interference filters, some types of antennas and various measurement
instruments. Generally the protective earth is also used as a functional earth, though
this requires care in some situations.
8.2.Types of earthing
1. Power or System
2. Equipment Safety
The outer housing of electrical equipment is earthed by directly connecting it to a
earth grid or earth electrode, thereby providing a low resistance path to ground. In
case of a fault involving earth the live part of the equipment gets connected with the
low resistance earth path. This produces high earth fault current and the protective
devices in the circuit disconnects the circuit from the power source thereby reducing
further damage to the equipment.
Neutral of electrical equipment are also earthed for equipment safety. Like, neutral
of generators in power plants are earthed through Neutral Grounding Resistor to limit
the earth fault current. Three phase transformer's neutral are earthed to provide neutral
point to supply single phase loads like lighting and small appliances.
CHAPTER 8 SYSTEM GROUNDING
172
ยฒ
ยฒ
ยฒ
8.3.safety or protective
Human Safety:
If a person touches an appliance which has an earth fault in it he will not get an
electric shock as his body (standing on the earth) and the equipment's body are at the
same potential provided the equipment is earthed properly. Thus proper earthing
protects a person from getting electric shock.
That's in the design of villas & apartments we had:
Adding the neutral & earth lines at the riser to the 3 phase or even 1 phase
& here is single line diagram of one of the model, added cable specifications.
CHAPTER 8 SYSTEM GROUNDING
173
8.4.System Earthing
8.4.1.Earthing requirements
Each electrically separate part of a system, which is magnetically coupled to other
parts at the transformation points, must be separately earthed.
The purpose of earth connections in different parts of a system differs. But
generally one or more of the following is fulfilled:
a) Zero phase-sequence protection. The earth connection must provide a path of
low impedance and adequate thermal capacity for earth fault (zero sequence) current
so that protective relays may operate satisfactorily.
b) Equipment or protective earthing. This is to ensure the safety of the public and
of the personal that operate electrical equipment.
c) Limitation of earth potential differences. This is to avoid injury or death to
persons or to animals that are more susceptible to electric shock than human begins.
d) Lightning and over voltage protection. This conducts to earth charges due to
lightning and protects equipment from over-voltage by means of surge arresters to
which the earth connection is made.
On any transmission or distribution system, these requirements are satisfied by
both system earths and equipment earths. There must also be adequate bonding of the
connections throughout the earthing system to ensure that currents to earth of the
highest magnitude may be carried without fusing of joints or of the earth conductor
itself and without appreciable voltage drop.
8.4.2. Means of earthing
System earthing may be direct, by a connection straight to earth, or indirect with a
resistor or reactor connected in the earth lead. The earth connection is made to the
system neutral (star point) where this exists or, on a true 3-phase system, by
establishing an artificial star point.
The earth wire, when present, not only provides lightning protection but, in the
event of a fault to earth, it provides a path to the nearest system earth for zero phase-
sequence currents additional to that provided by the earth electrodes and the earth
itself.
For outdoor equipment which is manually operated, the best protection which may
be afforded the operator is the provision of an earth-mat, bonded to the equipment at
the point where a man must stand to operate it. In the event of a fault to earth, the
equipment and the earth-mat, has no voltage across the body.
CHAPTER 8 SYSTEM GROUNDING
174
8.4.3. neutral systems
8.4.3.1. Insulated neutral system
Under healthy, balanced conditions, the star-point will be at earth potential even
though it is not connected to earth. When a ground fault occurs on one line, as shown.
The fault current is limited by the line to earth capacitances, one of which shorted out
by itself. Thus the fault current (If) is the pharos sum of an alternator stator winding or
transformer secondary winding with unearthed star-point is shown in fig.
8.5.Methods of Earting
DISAVANTAGES ADVANTAGES EXPLAINING TYPE
* The earth fault current
is heavy.
* Earth connections
must be made at
vulnerable point.
* Earth fault should be
isolated due to heavy I
fault.
*The star-point is always
at earth potential so that
when an earth fault occurs
on one line, the potential
difference between
healthy lines & earth can't
exceed max V phase.
*Simple protective
system.
*An arcing ground fault
can't occur.
*Here a direct metallic
connectionโs made
from the neutral of
system to one or more
earth electrodes.
*The earth electrodes
may be of plates, rods,
or pipes buried in the
ground.
1. Solid earthing
*Loss of power occurs
in resistance.
*It adds to the cost of
resistor & lightening
arrestors have to be
added.
*It facilitates the use of
discriminative protective
gear.
*It minimizes the hazards
of arcing grounds.
*It improves the system
stability.
*Here heavy ground
current can be reduced
by inserting a current
limiting device
between the neutral of
the system & earth.
*One of the current
limiting devices:
(resistance โ metallic
or liquid).
2.Resistive earthing
*It means earthing
through an impedance
(reactive) & ratio of
X0/X1>3
3.Reactance earthing
*By earthing through
Peterson coil the
effectโs to prevent
unbalanced
capacitance currents
entering earth fault.
4. Arc suppression
coil (Paterson coil).
CHAPTER 8 SYSTEM GROUNDING
175
8.6.Circuits & equations
EQUATION EQUIVALENT CIRCUIT TYPE
๐ผ๐น๐๐ข๐๐ก =3 Vphase
Z1 + Z2 + Z2
1. Solid earthing.
๐ =Vline
3 โ ๐ผ
2. Resistive earthing.
๐ผ๐น๐๐ข๐๐ก =Vphase
๐๐
3. Arc suppression coil
( Peterson coil )
CHAPTER 8 SYSTEM GROUNDING
176
8.7.Earth Resistivity & Gradient
It varies widely between different types of soil & is affected by the moisture
content.
Ranges of approximate values for the various types of soil are shown in table
RESISTIVITY (ฮฉ/m) TYPES OF SOIL
10-16 Clay &Loam
80-200 Sandy clay
150-300 Marsh peat
130-500 Sand
Up to 1000 Rock & chalk
8.8.Earth electrodes &networks
8.8.1Hemi sphere
Resistance= ๐
2ร๐ร๐ .
Resistance = ๐
4ร๐ร๐ . (for large burial depth)
CHAPTER 8 SYSTEM GROUNDING
177
8.8.2. Driven rod
8.8.3. Multi driven electrode.
Where ฮฑ =(r/s)
8.8.4. Buried plate electrode.
RESISTANCE TYPE
๐ = 0.5(1 + ๐ผ) 1. Tow rods in parallel
๐ =(2 + ๐ผ โ 4๐ผ2)
6โ 7๐ผ 2. Three rods in one line
๐ =(1 + 2๐ผ)
3 3. Three rods in triangle
๐ =(12 + 16๐ผ โ 21๐ผ2)
(48โ 40๐ผ) 4. Four rods on one line
RESISTANCE TYPE
R =ฯ
8r(1 +
๐
2.5๐ + ๐) 1. Normal case
๐ =ฯ
8r 2. Infinite depth
๐ =ฯ
4r 3. Zero depth
CHAPTER 8 SYSTEM GROUNDING
178
8.5.Burried horizontal wires
๐ =๐
2๐๐ฟ[๐๐๐๐(
๐
๐) + ๐(
๐
๐)]
CHAPTER 8 SYSTEM GROUNDING
179
8.9. measurement of earth electrode resistance & earth loop
impedance
Equation Figure Explain Type
๐ ๐ฅ = 0.5(๐ 1 + ๐ 2 + ๐ 3)
*A transformer supplies
current to the electrode
under test via the earth to
an auxiliary one (50m
apart) , h=.618d.,
*There's third electrode in
between, if voltmeter
between aux., third
electrode reach min. that's
proper place.
1. Fall of potential
method
*Suitable for the high
values of electrode
resistance such as tower
footings or single isolated
equipment.
2. The three point
method
๐ผ๐ก โ ๐ ๐ก = ๐ธ๐
*Measures the series
resistance & an aux.
electrode by means of the
galvanometer 's connected
between the sliding
contact & a second aux.
electrode
3. The ratio method
8.10. Substation earthing:
The requirements for s/s earthing are to dissipate to the earth a large amount
current of the order of thousands of amperes & to control the potential gradient over
the whole s/s area &to avoid Vstep ,Vtouch,Vmech.
๐ =๐
(1
4๐+
1
๐ฟ) ,
Where:
ฯ is average earth resistivity.
r is radius of circular plate.
L is total length of buried conductor.
0.1-0.015 ฯ *(V)over a horizontal distance of 1 m Vstep
๐ธ๐ก๐๐ข๐ ๐ =(165 + 0.25๐)
๐ก
, t =time of clearing fault
0.6-0.8 ฯ
*(V) between a structure earthed to
the mesh &a point on earth surface 1m
away. Vtouch
๐ธ๐๐๐ ๐ = ๐๐๐๐๐๐
๐
,Km,Ki coefficients
ฯ
*(V) between a structure to a point on
earth at the center of a rectangular
formed by mesh conductors. Vmesh
CHAPTER 8 SYSTEM GROUNDING
180
8.11.The high pulse voltage E.S.E. lightening conductor
A lightning rod (AUS) or lightning conductor (UK) is
a metal rod or conductor mounted on top of a building and
electrically connected to the ground through a wire, to
protect the building in the event of lightning. If lightning
strikes the building it will preferentially strike the rod, and
be conducted harmlessly to ground through the wire,
instead of passing through the building, where it could start
a fire or cause electrocution. A lightning rod is a single
component in a lightning protection system. In addition to
rods placed at regular intervals on the highest portions of a
structure, a lightning protection system typically includes a
rooftop network of conductors, multiple conductive paths
from the roof to the ground, bonding connections to
metallic objects within the structure and a grounding
network. The rooftop lightning rod is a metal strip or rod,
usually of copper or aluminum. Lightning protection systems are installed on structures, trees,
monuments, bridges or water vessels to protect from lightning damage. Individual lightning
rods are sometimes called finials, air terminals or strike termination devices & thus we have earthed from the building till the substation.
The Shopping Mall
Chapter 9
CHAPTER 9 THE SHOPPING MALL
181
Chapter 9
The Shopping Mall
9.1 Introduction
In this chapter we will lay down the full design of a three story shopping mall
containing 78 outlets and 2 cinema screens to better serve our layoutโs population
prosperity and welfare.
The design includes mall lighting details and normal and power socket placement as
well as the detailed wiring scheme and circuit breaker ratings and cable trays
specifications.
The shopping mall is equipped with an emergency backup electrical scheme to avoid
mall blackout and severe under voltage which could harm connected appliances.
During mall black out the emergency lighting will regain function after a limited
time no more than 15 seconds which is the time taken by the emergency generator to
start. The emergency lighting illuminates the mall halls and exit stairs which
facilitates the easy exit of customers and mall personnel.
In the following sections we will show each floorโs lighting calculations and
electrical wiring specifications.
9.2 Ground Floor_
9.2.1_Ground Floor Lighting Calculations_
The lighting calculations are done on basis of 300 lux for stores and 150 lux for hall
ways and stairs. Also a utilization factor of 0.66 and a maintenance factor of 0.8
according to a weekly mall cleaning basis
The used equation is: ๐(๐๐ข๐๐๐๐ ๐๐ ๐๐๐๐๐ ) =๐ธโ๐ด
๐ขโ๐โฮท
CHAPTER 9 THE SHOPPING MALL
182
Place Lux Area U m efficacy(
ฮท)
number of
lamps
Integer number
of lamps
lamp Power
PF Installe
d wattage
Current
store1 300 116.5 0.66 0.8 35 36.37138 37 52 0.8 1924 10.9318
store2 300 161.2 0.66 0.8 35 50.32517 51 52 0.8 2652 15.0682
Electrical Room 1
300 14.43 0.41 0.6 80 5.499238 8 40 0.8 320 1.81818
store4 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636
store5 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636
store6 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636
store7 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636
store8 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636
store9 300 22.94 0.58 0.8 35 8.149394 8 52 0.8 416 2.36364
store10(bathroom)
300 14.43 0.35 0.8 80 4.831473 8 40 0.8 320 1.81818
store11 300 29.26 0.58 0.8 35 10.39456 10 52 0.8 520 2.95455
store12 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273
store13 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273
store14 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273
store15 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273
store16(bathroom)
300 14.43 0.35 0.8 80 4.831473 8 40 0.8 320 1.81818
Electrical Room 2
300 43.64 0.6 0.6 80 11.36458 12 40 0.8 480 2.72727
store18 300 33.07 0.58 0.8 35 11.74628 12 52 0.8 624 3.54545
store19 300 17 0.58 0.8 35 6.039219 6 52 0.8 312 1.77273
store20 300 33.07 0.58 0.8 35 11.74628 12 52 0.8 624 3.54545
store21 300 17 0.58 0.8 35 6.039219 6 52 0.8 312 1.77273
store22 300 20.83 0.58 0.8 35 7.398044 8 52 0.8 416 2.36364
store23 300 48.46 0.58 0.8 35 17.21533 16 52 0.8 832 4.72727
store24 300 116.5 0.66 0.8 35 36.37138 37 52 0.8 1924 10.9318
store25 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364
store26 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455
store27 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455
store28 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364
store29 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364
store30 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455
store31 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455
store32 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364
coridoor1 150 108 0.64 0.8 35 34.77243 31 26 0.8 806 4.57955
coridoor2 150 99.84 0.64 0.8 35 32.14286 28 26 0.8 728 4.13636
coridoor3 150 211 0.64 0.8 35 67.93012 68 26 0.8 1768 10.0455
coridoor4 150 59.45 0.64 0.8 35 19.13987 20 26 0.8 520 2.95455
coridoor5 150 61.22 0.64 0.8 35 19.71004 20 26 0.8 520 2.95455
coridoor6 150 50.13 0.64 0.8 35 16.1402 16 26 0.8 416 2.36364
coridoor7 150 83.74 0.64 0.8 35 26.95828 27 26 0.8 702 3.98864
coridoor8 150 83.74 0.64 0.8 35 26.95956 27 26 0.8 702 3.98864
stairs1 150 58.8 0.41 0.6 80 22.40854 24 20 0.8 480 2.72727
stairs2 150 81.6 0.41 0.6 80 31.09756 32 20 0.8 640 3.63636
stairs3 150 91 0.41 0.6 80 34.67988 36 20 0.8 720 4.09091
outdoor lighting
_ _ _ _ _ _ 17 70 1 1190 5.40909
CHAPTER 9 THE SHOPPING MALL
183
CHAPTER 9 THE SHOPPING MALL
184
9.2.2 Ground Floor Socket Calculations & Wiring_
Room Main
currents
line numb
er
line type
current MCB
Light Line C.S.A
line numb
er line type
number of socke
ts
Current
MCB
Socket Lines C.S.A
shop 1 42.01181
818
1 Lightin
g 1 5.465909
091 10
2*2.5 mm2
3 normal
sockets 1 7 4.4 10
3x2.5mm2
2 Lightin
g 2 5.465909
091 10
2*2.5 mm2
4 power
sockets 1 1 20 25
3x4mm2
5 power
sockets 2 1 20 25
3x4mm2
shop 2 44.76939
394
1 Lightin
g 1 3.643939
394 10
2*2.5 mm2
4 normal
sockets 1 7 4.4 10
3x2.5mm2
2 Lightin
g 2 5.022727
273 10
2*2.5 mm2
5 power
sockets 1 1 20 25
3x4mm2
3 Lightin
g 3 5.022727
273 10
2*2.5 mm2
6 power
sockets 2 1 20 25
3x4mm2
Electrical Room 1
4.618181818
1 Lightin
g 1 1.818181
818 10
2*2.5 mm2
2 normal
sockets 1 3 2.8 10
3x2.5mm2
shop 4 8.536363
636 1
Lighting 1
4.136363636
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 5 8.536363
636 1
Lighting 1
4.136363636
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 6 8.536363
636 1
Lighting 1
4.136363636
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 7 8.536363
636 1
Lighting 1
4.136363636
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 8 8.536363
636 1
Lighting 1
4.136363636
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 9 6.363636
364 1
Lighting 1
2.363636364
10 2*2.5 mm2
2 normal
sockets 1 6 4 10
3x2.5mm2
Bathroom 1 20.99818
182
1 Lightin
g 1 1.818181
818 10
2*2.5 mm2
2 normal
sockets 1 2 2.4 10
3x2.5mm2
3 power
sockets 1 1 25 32
3*6 mm2
shop 11 7.354545
455 1
Lighting 1
2.954545455
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 12 4.972727
273 1
Lighting 1
1.772727273
10 2*2.5 mm2
2 normal
sockets 1 4 3.2 10
3x2.5mm2
shop 13 4.972727
273 1
Lighting 1
1.772727273
10 2*2.5 mm2
2 normal
sockets 1 4 3.2 10
3x2.5mm2
shop 14 4.972727
273 1
Lighting 1
1.772727273
10 2*2.5 mm2
2 normal
sockets 1 4 3.2 10
3x2.5mm2
shop 15 4.972727
273 1
Lighting 1
1.772727273
10 2*2.5 mm2
2 normal
sockets 1 4 3.2 10
3x2.5mm2
Bathroom 2 4.218181
818 1
Lighting 1
1.818181818
10 2*2.5 mm2
2 normal
sockets 1 2 2.4 10
3x2.5mm2
Electrical Room 2
5.927272727
1 Lightin
g 1 2.727272
727 10
2*2.5 mm2
2 normal
sockets 1 4 3.2 10
3x2.5mm2
shop 18 7.945454
545 1
Lighting 1
3.545454545
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 19 4.972727
273 1
Lighting 1
1.772727273
10 2*2.5 mm2
2 normal
sockets 1 4 3.2 10
3x2.5mm2
shop 20 7.945454
545 1
Lighting 1
3.545454545
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 21 4.972727
273 1
Lighting 1
1.772727273
10 2*2.5 mm2
2 normal
sockets 1 4 3.2 10
3x2.5mm2
shop 22 5.963636
364 1
Lighting 1
2.363636364
10 2*2.5 mm2
2 normal
sockets 1 5 3.6 10
3x2.5mm2
CHAPTER 9 THE SHOPPING MALL
185
shop 23 9.127272
727 1
Lighting 1
4.727272727
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 24 38.90954
545
1 Lightin
g 1 2.363636
364 10
2*2.5 mm2
3 normal
sockets 1 7 4.4 10
3x2.5mm2
2 Lightin
g 2 5.465909
091 10
2*2.5 mm2
4 power
sockets 1 1 20 25
3x4mm2
5 power
sockets 2 1 20 25
3x4mm2
shop 25 10.01363
636 1
Lighting 1
5.613636364
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 26 7.354545
455 1
Lighting 1
2.954545455
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 27 7.354545
455 1
Lighting 1
2.954545455
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 28 10.01363
636 1
Lighting 1
5.613636364
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 29 10.01363
636 1
Lighting 1
5.613636364
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 30 7.354545
455 1
Lighting 1
2.954545455
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
shop 31 7.354545
455 1
Lighting 1
2.954545455
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5cm2
shop 32 10.01363
636 1
Lighting 1
5.613636364
10 2*2.5 mm2
2 normal
sockets 1 7 4.4 10
3x2.5mm2
corridor 1
2.289772727
1 Lightin
g 1 2.289772
727 10
2*2.5 mm2
2.289772727
2 Lightin
g 2 2.289772
727 10
2*2.5 mm2
corridor 2
2.068 1 Lightin
g 1 2.068 10
2*2.5 mm2
2.068 2 Lightin
g 2 2.068 10
2*2.5 mm2
corridor 3
5 1 Lightin
g 1 5 10
2*2.5 mm2
5 2 Lightin
g 2 5 10
2*2.5 mm2
corridor 4
1.475 1 Lightin
g 1 1.475 10
2*2.5 mm2
1.475 2 Lightin
g 2 1.475 10
2*2.5 mm2
corridor 5
1.475 1 Lightin
g 1 1.475 10
2*2.5 mm2
1.475 2 Lightin
g 2 1.475 10
2*2.5 mm2
corridor 6
1.18 1 Lightin
g 1 1.18 10
2*2.5 mm2
1.18 2 Lightin
g 2 1.18 10
2*2.5 mm2
corridor 7
1.994 1 Lightin
g 1 1.994 10
2*2.5 mm2
1.994 2 Lightin
g 2 1.994 10
2*2.5 mm2
corridor 8
1.994 1 Lightin
g 1 1.994 10
2*2.5 mm2
1.994 2 Lightin
g 2 1.994 10
2*2.5 mm2
stairs 1 2.727272
727 1
Lighting 1
1.36364 10 2*2.5 mm2
stairs 2 3.636363
636 1
Lighting 1
1.36364 10 2*2.5 mm2
CHAPTER 9 THE SHOPPING MALL
186
stairs 3 4.090909
091 1
Lighting 1
1.36364 10 2*2.5 mm2
outdoor lighting
5.409090909
1 Lightin
g 1 5.409090
909 10
2*2.5 mm2
Water pump 1
20 1 Power Line 1 20 25 2x4mm
2
Water pump 2
20 1 Power Line 1 20 25 2x4mm
2
Escalator 1 30.303 1 Power Line 1 30.30
3 40
2x10mm2
Escalator 2 30.303 1 Power Line 1 30.30
3 40
2x10mm2
9.2.3 Ground Floor Local Feeders_
line Room Main currents MCB Rating
C.S.A (1ph+n+e)
m1 shop 1 42 63 3x16mm2
m2 shop 2 44.7 63 3x16mm2
m4 shop 4 8.536363636 16 3x3mm2
m5 shop 5 8.536363636 16 3x3mm2
m6 shop 6 8.536363636 16 3x3mm2
m7 shop 7 8.536363636 16 3x3mm2
m8 shop 8 8.536363636 16 3x3mm2
m9 shop 9 6.363636364 16 3x3mm2
m11 shop 11 7.354545455 16 3x3mm2
m12 shop 12 4.972727273 10 3x2.5mm2
m13 shop 13 4.972727273 10 3x2.5mm2
m14 shop 14 4.972727273 10 3x2.5mm2
m15 shop 15 4.972727273 10 3x2.5mm2
m18 shop 18 7.945454545 16 3x3mm2
m19 shop 19 4.972727273 10 3x2.5mm2
m20 shop 20 7.945454545 16 3x3mm2
m21 shop 21 4.972727273 10 3x2.5mm2
m22 shop 22 5.963636364 10 3x2.5mm2
m23 shop 23 9.127272727 16 3x3mm2
m24 shop 24 38.9 63 3x16mm2
m25 shop 25 10.01363636 16 3x3mm2
m26 shop 26 7.354545455 16 3x3mm2
m27 shop 27 7.354545455 16 3x3mm2
m28 shop 28 10.01363636 16 3x3mm2
CHAPTER 9 THE SHOPPING MALL
187
m29 shop 29 10.01363636 16 3x3mm2
m30 shop 30 7.354545455 16 3x3mm2
m31 shop 31 7.354545455 16 3x3mm2
m32 shop 32 10.01363636 16 3x3mm2
m3 Electrical Room 1 4.618181818 10 3x2.5mm2
m17 Electrical Room 2 5.927272727 10 3x2.5mm2
m10 Bathroom 1 20.99818182 32 3x6mm2
m16 Bathroom 2 4.218181818 10 3x2.5mm2
m33 corridor 1
2.289772727 10 2x2.5mm2
m34 2.289772727 10 2x2.5mm2
m35 corridor 2
2.068 10 2x2.5mm2
m36 2.068 10 2x2.5mm2
m37 corridor 3
5 10 2x2.5mm2
m38 5 10 2x2.5mm2
m39 corridor 4
1.475 10 2x2.5mm2
m40 1.475 10 2x2.5mm2
m41 corridor 5
1.475 10 2x2.5mm2
m42 1.475 10 2x2.5mm2
m43 corridor 6
1.18 10 2x2.5mm2
m44 1.18 10 2x2.5mm2
m45 corridor 7
1.994 10 2x2.5mm2
m46 1.994 10 2x2.5mm2
m47 corridor 8
1.994 10 2x2.5mm2
m48 1.994 10 2x2.5mm2
m49 stairs 1 2.727272727 10 2x2.5mm2
m50 stairs 2 3.636363636 10 2x2.5mm2
m51 stairs 3 4.090909091 10 2x2.5mm2
m52 outdoor lighting 5.409090909 10 2x2.5mm2
m53 Water pump 1 20 25 2x4mm2
m54 Water pump 2 20 25 2x4mm2
m55 Escalator 1 30.303 40 2x10mm2
m56 Escalator 2 30.303 40 2x10mm2
CHAPTER 9 THE SHOPPING MALL
188
9.2.4 Ground Floor SMDBs_& Cable Tray Dimension
It should be noted that each floor contains 2 electrical rooms, the first electrical
room consists of one service panel board "SMDB-G1" where the G indicates that this
panel board is in the ground floor and the numeral 1 indicates that this service panel is
located in the electrical room 1.The first electrical room also contains an emergency
panel board "EMDB-G". The second electrical room consists of only one service
panel "SMDB-G2". The service and emergency panel's enclosures are compliant with
the standards "service enclosure Ip40 (NEMA1)"
line Room Main currents
MCB Ratin
g
C.S.A (1ph+n+e)
Local Panel Code
Service Panel Main
current (per
phase)
Service Panel 3ph
MCCB Rating
Service Panel Incoming Cable
(3ph+n+e)
Cable Overall
Diameter
Cable Tray Width (mm)
Installed Cable Tray Width (cm)
E L E C T R I C A L
R O O M
1
S M D B - G 1
m1 store 1 42 63 3x16m
m2 LPP-G1-1
90.199091
100 (3x35+16+1
6)mm2
6.8
554.4
60
m2 store 2 44.7 63 3x16m
m2 LPP-G1-2
6.8
m4 store 4 8.5363636
36 16
3x3mm2
LPP-G1-4
3.8
m5 store 5 8.5363636
36 16
3x3mm2
LPP-G1-5
3.8
m6 store 6 8.5363636
36 16
3x3mm2
LPP-G1-6
3.8
m7 store 7 8.5363636
36 16
3x3mm2
LPP-G1-7
3.8
m8 store 8 8.5363636
36 16
3x3mm2
LPP-G1-8
3.8
m9 store 9 6.3636363
64 16
3x3mm2
LPP-G1-9
3.8
m11 store 11 7.3545454
55 16
3x3mm2
LPP-G1-11
3.8
m12 store 12 4.9727272
73 10
3x2.5mm2
LPP-G1-12
3.6
m25 store 25 10.013636
36 16
3x3mm2
LPP-G1-25
3.8
m26 store 26 7.3545454
55 16
3x3mm2
LPP-G1-26
3.8
m27 store 27 7.3545454
55 16
3x3mm2
LPP-G1-27
3.8
m28 store 28 10.013636
36 16
3x3mm2
LPP-G1-28
3.8
CHAPTER 9 THE SHOPPING MALL
189
m3 Electric
al Room 1
4.618181818
10 3x2.5m
m2 LPP-G1-3
3.6
m10 Bathroo
m 1 20.998181
82 32
3x6mm2
LPP-G1-10
5
m33 corridor
1 2.8068181
82 10
2x2.5mm2
3.6
m35 corridor
2 2.068 10
2x2.5mm2
3.6
m37 corridor
3 5 10
2x2.5mm2
3.6
m45 corridor
7 1.994 10
2x2.5mm2
3.6
m53 Water
pump 1 20 25
2x4mm2
4.6
m55 Escalat
or 1 30.303 40
2x10mm2
5.8
E L E C T R I C A L
R O O M
2
S M D B - G 2
m13 store 13 4.9727272
73 10
3x2.5mm2
LPP-G2-13
67.154455
80 (3x25+16+1
6)mm2
3.6
543.6
60
m14 store 14 4.9727272
73 10
3x2.5mm2
LPP-G2-14
3.6
m15 store 15 4.9727272
73 10
3x2.5mm2
LPP-G2-15
3.6
m18 store 18 7.9454545
45 16
3x3mm2
LPP-G2-18
3.8
m19 store 19 4.9727272
73 10
3x2.5mm2
LPP-G2-19
3.6
m20 store 20 7.9454545
45 16
3x3mm2
LPP-G2-20
3.8
m21 store 21 4.9727272
73 10
3x2.5mm2
LPP-G2-21
3.6
m22 store 22 5.9636363
64 10
3x2.5mm2
LPP-G2-22
3.6
m23 store 23 9.1272727
27 16
3x3mm2
LPP-G2-23
3.8
m24 store 24 38.9 63 3x16m
m2
LPP-G2-24
6.8
m29 store 29 10.013636
36 16
3x3mm2
LPP-G2-29
3.8
m30 store 30 7.3545454
55 16
3x3mm2
LPP-G2-30
3.8
m31 store 31 7.3545454
55 16
3x3mm2
LPP-G2-31
3.8
m32 store 32 10.013636
36 16
3x3mm2
LPP-G2-32
3.8
CHAPTER 9 THE SHOPPING MALL
190
m16 Bathroo
m 2 4.2181818
18 10
3x2.5mm2
LPP-G2-16
3.6
m17 Electric
al Room 2
5.927272727
10 3x2.5m
m2
LPP-G2-17
3.6
m39 corridor
4 1.475 10
2x2.5mm2
3.6
m41 corridor
5 1.475 10
2x2.5mm2
3.6
m43 corridor
6 1.18 10
2x2.5mm2
3.6
m47 corridor
8 1.994 10
2x2.5mm2
3.6
m52 outdoor lightnin
g
5.409090909
10 2x2.5m
m2
3.6
m54 Water
pump 2 20 25
2x4mm2
4.6
m56 Escalat
or 2 30.303 40
2x10mm2
5.8
CHAPTER 9 THE SHOPPING MALL
191
9.2.5 Ground Floor Emergency Backup Scheme_
The shopping mall is equipped with an emergency backup electrical scheme to avoid
mall blackout and severe under voltage which could harm connected appliances.
During mall black out the emergency lighting will regain function after a limited
time no more than 15 seconds which is the time taken by the emergency generator to
start. The emergency lighting illuminates the mall halls and exit stairs which
facilitates the easy exit of customers and mall personnel.
The following table shows the emergency panel connected loads which mainly
include 50% of Hall way lighting providing illumination of 75 lux since the mall
shops are not equipped with a backup lighting plan, so this percentage of hallway
lighting will provide enough illumination to assure both customer and personnel
safety.
Emergency Panel (Lighting :75 lux) EMDB-G
Place Line Line current MCB Rating
C.S.A Main Panel
Current Main MCB
Main CSA
Corridor 1 m34e 2.806818182 10 2x2.5mm2
36.59736364 40A 2x10mm2
Corridor 2 m36e 2.068 10 2x2.5mm2
Corridor 3 m38e 5 10 2x2.5mm2
Corridor 4 m40e 1.475 10 2x2.5mm2
Corridor 5 m42e 1.475 10 2x2.5mm2
Corridor 6 m44e 1.18 10 2x2.5mm2
Corridor 7 m46e 1.994 10 2x2.5mm2
Corridor 8 m48e 1.994 10 2x2.5mm2
Bathroom 1 m57e 1.81 10 2x2.5mm2
Bathroom 2 m58e 1.81 10 2x2.5mm2
Electrical Room 1 m59e 1.81 10 2x2.5mm2
Electrical Room 2 m60e 2.72 10 2x2.5mm2
stairs 1 m48e 2.727272727 10 2x2.5mm2
stairs 2 m50e 3.636363636 10 2x2.5mm2
stairs 3 m51e 4.090909091 10 2x2.5mm2
CHAPTER 9 THE SHOPPING MALL
192
CHAPTER 9 THE SHOPPING MALL
193
9.3 First Floor_
9.3.1 First Floor Lighting Calculations_
The lighting calculations are done on basis of 300 lux for stores and 150 lux for hall
ways and stairs. Also a utilization factor of 0.66 and a maintenance factor of 0.8
according to a weekly mall cleaning basis
The used equation is: ๐(๐๐ข๐๐๐๐ ๐๐ ๐๐๐๐๐ ) =๐ธโ๐ด
๐ขโ๐โฮท
P L A C E
L U X
A R E A
u m ฮท No. of
Lamps
Int. No. of Locations
Lamp
Wattage
PF
Installed
Wattage
Light Line
Current
Light Line 1
Light Line 2
C.B of Line 1
C.B of Line 2
Light Line 1 CSA
Light Line 2 CSA
Store 1
300
78.29
0.66
0.8
35
24.4410277
24 52 0.8
1248 7.09090
9091 3.54545455
3.545454545
10 10 2.5 2.5
Store 2
300
78.29
0.66
0.8
35
24.4410277
24 52 0.8
1248 7.09090
9091 3.54545455
3.545454545
10 10 2.5 2.5
Store 3
300
82.79
0.66
0.8
35
25.846029
25 52 0.8
1300 7.38636
3636 3.69318182
3.693181818
10 10 2.5 2.5
Store 4
300
28.564
0.66
0.8
35
8.91733267
8 52 0.8
416 2.36363
6364 2.36363636
_ 10 _ 2.5 _
Store 5
300
14.171
0.66
0.8
35
4.42401349
5 52 0.8
260 1.47727
2727 1.47727273
_ 10 _ 2.5 _
Store 6
300
14.171
0.66
0.8
35
4.42401349
5 52 0.8
260 1.47727
2727 1.47727273
_ 10 _ 2.5 _
Store 7
300
14.171
0.66
0.8
35
4.42401349
5 52 0.8
260 1.47727
2727 1.47727273
_ 10 _ 2.5 _
Store 8
300
14.171
0.66
0.8
35
4.42401349
5 52 0.8
260 1.47727
2727 1.47727273
_ 10 _ 2.5 _
Store 9
300
43.62
0.66
0.8
35
13.6176324
14 52 0.8
728 4.13636
3636 4.13636364
_ 10 _ 2.5 _
Store 10
300
33.108
0.66
0.8
35
10.335758
10 52 0.8
520 2.95454
5455 2.95454545
_ 10 _ 2.5 _
Store 11
300
16.278
0.66
0.8
35
5.08163711
6 52 0.8
312 1.77272
7273 1.77272727
_ 10 _ 2.5 _
Store 12
300
33.108
0.66
0.8
35
10.335758
10 52 0.8
520 2.95454
5455 2.95454545
_ 10 _ 2.5 _
Store 13
300
16.278
0.66
0.8
35
5.08163711
6 52 0.8
312 1.77272
7273 1.77272727
_ 10 _ 2.5 _
Store 14
300
21.293
0.66
0.8
35
6.64725899
7 52 0.8
364 2.06818
1818 2.06818182
_ 10 _ 2.5 _
Store 15
300
47.767
0.66
0.8
35
14.9121816
16 52 0.8
832 4.72727
2727 4.72727273
_ 10 _ 2.5 _
Store 16
300
120.9
0.66
0.8
35
37.7438811
38 52 0.8
1976 11.2272
7273 5.61363636
5.613636364
10 10 2.5 2.5
Store 17
300
121.02
0.66
0.8
35
37.7803134
38 52 0.8
1976 11.2272
7273 5.61363636
5.613636364
10 10 2.5 2.5
Store 18
300
166.23
0.66
0.8
35
51.8953234
52 52 0.8
2704 15.3636
3636 7.68181818
7.681818182
10 10 2.5 2.5
Store 19
300
16.107
0.66
0.8
35
5.02840909
6 52 0.8
312 1.77272
7273 1.77272727
_ 10 _ 2.5 _
Store 20
300
46.7 0.66
0.8
35
14.5791708
15 52 0.8
780 4.43181
8182 4.43181818
_ 10 _ 2.5 _
Store 21
300
58.347
0.66
0.8
35
18.2152535
19 52 0.8
988 5.61363
6364 5.61363636
_ 10 _ 2.5 _
Store 22
300
46.7 0.66
0.8
35
14.5791708
15 52 0.8
780 4.43181
8182 4.43181818
_ 10 _ 2.5 _
Store 23
300
46.7 0.66
0.8
35
14.5791708
15 52 0.8
780 4.43181
8182 4.43181818
_ 10 _ 2.5 _
Store 24
300
28.462
0.66
0.8
35
8.88548951
9 52 0.8
468 2.65909
0909 2.65909091
_ 10 _ 2.5 _
CHAPTER 9 THE SHOPPING MALL
194
Store 25
300
28.462
0.66
0.8
35
8.88548951
9 52 0.8
468 2.65909
0909 2.65909091
_ 10 _ 2.5 _
Store 26
300
46.7 0.66
0.8
35
14.5791708
15 52 0.8
780 4.43181
8182 4.43181818
_ 10 _ 2.5 _
Hall 1
150
80.52
0.64
0.8
35
25.9229052
18 26 0.8
468 2.65909
0909 1.32954545
1.329545455
10 10 2.5 2.5
Hall 2
150
198.18
0.64
0.8
35
63.8027988
48 26 0.8
1248 7.09090
9091 3.5 3.5 10 10 2.5 2.5
Hall 3 150
83.571
0.64
0.8
35
26.9051554
20 26 0.8
520 2.95454
5455 1.47727273
1.477272727
10 10 2.5 2.5
Hall 4 150
58.8 0.64
0.8
35
18.9302885
22 26 0.8
572 3.25 1.625 1.625 10 10 2.5 2.5
Hall 5 150
114.38
0.66
0.8
35
35.708042
28 26 0.8
728 4.13636
3636 2.06818182
2.068181818
10 10 2.5 2.5
Hall 6 150
54.108
0.64
0.8
35
17.4196321
20 26 0.8
520 2.95454
5455 1.47727273
1.477272727
10 10 2.5 2.5
Hall 7 150
33.891
0.64
0.8
35
10.9109289
9 26 0.8
234 1.32954
5455 1.32954545
_ 10 10 2.5 2.5
Hall 8 150
74.227
0.64
0.8
35
23.8969136
22 26 0.8
572 3.25 1.625 1.625 10 10 2.5 2.5
Hall 9 150
74.227
0.64
0.8
35
23.8969136
20 26 0.8
520 2.95454
5455 1.47727273
1.477272727
10 10 2.5 2.5
WC1 300
14.438
0.35
0.8
80
4.83428571
5 40 0.8
200 1.13636
3636 1.13636364
_ 10 _ 2.5 _
WC2 300
14.438
0.35
0.8
80
4.83428571
5 40 0.8
200 1.13636
3636 1.13636364
_ 10 _ 2.5 _
Entrance
300
115.88
36 70 0.7
2520 16.3636
3636 8.18 8.18 10 10 2.5 2.5
CHAPTER 9 THE SHOPPING MALL
195
CHAPTER 9 THE SHOPPING MALL
196
9.3.2 First Floor Socket Calculations & Wiring_
L I N E
R O O M
Store Main
Current
LINE number
Line Type
C U R R E N T
C B
C.S.A (1phase+neut
ral) mm
2
Line No.
T Y P E
Number Of Sockets
C U R R E N T
C B
C.S.A (1phase+neutral+earth)m
m2
m1 Shop1 38.08
L1 LIGHTING
3.5 10
2x2.5 L3 N.S 7 4.4 10
3x2.5
L2 LIGHTING
3.5 10
2x2.5 L4 P.S 1 20 25
3x4
L5 P.S 1 20 25
3x4
m2 Shop2 38.08
L1 LIGHTING
3.5 10
2x2.5 L3 N.S 7 4.4 10
3x2.5
L2 LIGHTING
3.5 10
2x2.5 L4 P.S 1 20 25
3x4
L5 P.S 1 20 25
3x4
m3 Shop3 38.38
L1 LIGHTING
3.8 10
2x2.5 L3 N.S 7 4.4 10
3x2.5
L2 LIGHTING
3.5 10
2x2.5 L4 P.S 1 20 25
3x4
L5 P.S 1 20 25
3x4
m4 Shop4 5.48 L1 LIGHTING
2.4 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m5 Shop5 3.71 L1 LIGHTING
1.47 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m6 Shop6 3.71 L1 LIGHTING
1.47 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m7 Shop7 3.71 L1 LIGHTING
1.47 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m8 Shop8 3.71 L1 LIGHTING
1.47 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m9 Electrical room 2
6.34 L1 LIGHTING
4.1 10
2x2.5 L2 N.S 4 3.2 16
3x3
m10 Shop10 5.19 L1 LIGHTING
2.95 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m11 Shop11 3.94 L1 LIGHTING
1.7 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m12 Shop12 5.19 L1 LIGHTING
2.95 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m13 Shop13 3.94 L1 LIGHTING
1.7 10
2x2.5 L2 N.S 4 3.2 10
3x2.5
m14 Shop14 4.59 L1 LIGHTING
2.07 10
2x2.5 L2 N.S 5 3.6 10
3x2.5
m15 Shop15 7.81 L1 LIGHTING
4.73 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m16 Shop16 42.28
L1 LIGHTING
5.6 10
2x2.5 L3 N.S 7 4.4 10
3x2.5
L2 LIGHTING
5.6 10
2x2.5 L4 P.S 1 20 25
3x4
L5 P.S 1 20 25
3x4
m17 Shop17 42.28
L1 LIGHTING
5.6 10
2x2.5 L3 N.S 7 4.4 10
3x2.5
L2 LIGHTING
5.6 10
2x2.5 L4 P.S 1 20 25
3x4
CHAPTER 9 THE SHOPPING MALL
197
L5 P.S 1 20 25
3x4
m18 shop18 46.48
L1 LIGHTING
7.7 10
2x2.5 L3 N.S 7 4.4 10
3x2.5
L2 LIGHTING
7.7 10
2x2.5 L4 P.S 1 20 25
3x4
L5 P.S 1 20 25
3x4
m19 Electrical room 1
3.76 L1 LIGHTING
1.8 10
2x2.5 L2 N.S 3 2.8 16
3x3
m20 shop20 7.48 L1 LIGHTING
4.4 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m21 shop21 8.68 L1 LIGHTING
5.6 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m22 shop22 7.48 L1 LIGHTING
4.4 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m23 shop23 7.48 L1 LIGHTING
4.4 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m24 shop24 5.73 L1 LIGHTING
2.65 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m25 shop25 5.73 L1 LIGHTING
2.65 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m26 shop26 7.48 L1 LIGHTING
4.4 10
2x2.5 L2 N.S 7 4.4 10
3x2.5
m27 Bathroo
m 1 20.58
L1 LIGHTING
1.4 10
2x2.5 L2 N.S 2 2.4 10
3x2.5
L3 P.S 1 25 32
3x6
m28
Bathroom 2
20.58
L1 LIGHTING
1.4 10
2x2.5 L2 N.S 2 2.4 10
3x2.5
L3 P.S 1 25
32
3x6
m29
HALL1
1.33 L29 LIGHTING
1.33 10
2x2.5
m30 1.33 L30 LIGHTING
1.33 10
2x2.5
m31
HALL2
3.5045 L31 LIGHTING
3.5045
10
2x2.5
m32 3.5045 L32 LIGHTING
3.5045
10
2x2.5
m33
HALL3
1.48 L33 LIGHTING
1.47727
3
10
2x2.5
m34 1.48 L34 LIGHTING
1.47727
3
10
2x2.5
m35
HALL4
1.625 L35 LIGHTING
1.625
10
2x2.5
m36 1.625 L36 LIGHTING
1.625
10
2x2.5
m37
HALL5
2 L37 LIGHTING
2.06818
2
10
2x2.5
m38 2 L38 LIGHTING
2.06818
2
10
2x2.5
m39
HALL6
1.48 L39 LIGHTING
1.47727
3
10
2x2.5
m40 1.48 L40 LIGHTING
1.47727
3
10
2x2.5
m41 HALL7 1.33 L41 LIGHTING
1.32954
10
2x2.5
CHAPTER 9 THE SHOPPING MALL
198
5
m42
HALL8
1.625 L42 LIGHTING
1.625
10
2x2.5
m43 1.625 L43 LIGHTING
1.625
10
2x2.5
m44
HALL9
1.48 L44 LIGHTING
1.47727
3
10
2x2.5
m45 1.48 L45 LIGHTING
1.47727
3
10
2x2.5
m46
Entrance
8.18 L46 LIGHTING
8.18 10
2x2.5
m47 8.18 L47 LIGHTING
8.18 10
2x2.5
m48 Escalato
r 3 30.303 1
Power
Line 1
30.303
40
3x10mm2
m49 Escalato
r 4 30.303 1
Power
Line 1
30.303
40
3x10mm2
9.3.3 First Floor Local Feeders
Line Room Main
Current MCB Rating C.S.A (1ph+n+e)
m1 Store 1 38.08 40 3x6mm2
m2 Store 2 38.08 40 3x6mm2
m3 Store 3 38.38 40 3x6mm2
m4 Store 4 5.48 10 3x2.5mm2
m5 Store 5 3.71 10 3x2.5mm2
m6 Store 6 3.71 10 3x2.5mm2
m7 Store 7 3.71 10 3x2.5mm2
m8 Store 8 3.71 10 3x2.5mm2
m10 Store 10 5.19 10 3x2.5mm2
m11 Store 11 3.94 10 3x2.5mm2
m12 Store 12 5.19 10 3x2.5mm2
m13 Store 13 3.94 10 3x2.5mm2
m14 Store 14 4.59 10 3x2.5mm2
m15 Store 15 7.81 10 3x2.5mm2
m16 Store 16 42.28 63 3x16mm2
m17 Store 17 42.28 63 3x16mm2
m18 Store 18 46.48 63 3x16mm2
m20 Store 20 7.48 10 3x2.5mm2
m21 Store 21 8.68 10 3x2.5mm2
m22 Store 22 7.48 10 3x2.5mm2
CHAPTER 9 THE SHOPPING MALL
199
m23 Store 23 7.48 10 3x2.5mm2
m24 Store 24 5.73 10 3x2.5mm2
m25 Store 25 5.73 10 3x2.5mm2
m26 Store 26 7.48 10 3x2.5mm2
m19 Electrical room 1
3.76 10 3x2.5mm2
m9 Electrical room 2
6.34 10 3x2.5mm2
m27 Bathroom
1 20.58 25 3x4mm2
m28 Bathroom
2 20.58 25 3x4mm2
m29 HALL1
1.33 10 2x2.5mm2
m30 1.33 10 2x2.5mm2
m31 HALL2
3.045 10 2x2.5mm2
m32 3.045 10 2x2.5mm2
m33 HALL3
1.48 10 2x2.5mm2
m34 1.48 10 2x2.5mm2
m35 HALL4
1.625 10 2x2.5mm2
m36 1.625 10 2x2.5mm2
m37 HALL5
2 10 2x2.5mm2
m38 2 10 2x2.5mm2
m39 HALL6
1.48 10 2x2.5mm2
m40 1.48 10 2x2.5mm2
m41 HALL7 1.33 10 2x2.5mm2
m42 HALL8
1.625 10 2x2.5mm2
m43 1.625 10 2x2.5mm2
m44 HALL9
1.48 10 2x2.5mm2
m45 1.48 10 2x2.5mm2
m46 Entrance
8.18 10 2x2.5mm2
m47 8.18 10 2x2.5mm2
m48 Escalator 3 30.303 40 2x10mm2
m49 Escalator 4 30.303 40 2x10mm2
CHAPTER 9 THE SHOPPING MALL
200
9.3.4 First Floor SMDBs_& Cable Tray Dimension_
It should be noted that each floor contains 2 electrical rooms, the first electrical
room consists of one service panel board "SMDB-F1" where the F indicates that this
panel board is in the First floor and the numeral 1 indicates that this service panel is
located in the electrical room 1.The first electrical room also contains an emergency
panel board "EMDB-F". The second electrical room consists of only one service panel
"SMDB-F2". The service and emergency panel's enclosures are compliant with the
standards "service enclosure Ip40 (NEMA1)"
line Room Main
currents
MCB
Rating
C.S.A (1ph+n+e)
Local Panel Code
Service Panel Main
current (per
phase)
Service Panel 3ph
MCCB Rating
Service Panel Incoming Cable
(3ph+n+e)
Cable Overall Diamet
er
Cable Tray
Width (mm)
Installed Cable Tray
Width (cm)
E L E C T R I C A L
R O O M
1
S M D B - F 1
m1 Store 1 38.08 40 3x6mm2 LPP-F1-1
106.2026667
160A (3x70+35+35)
mm2
5
536.4
60
m2 Store 2 38.08 40 3x6mm2 LPP-F1-2
5
m3 Store 3 38.38 40 3x6mm2 LPP-F1-3
5
m4 Store 4 5.48 10 3x2.5m
m2 LPP-F1-4
3.6
m5 Store 5 3.71 10 3x2.5m
m2 LPP-F1-5
3.6
m6 Store 6 3.71 10 3x2.5m
m2 LPP-F1-6
3.6
m17 Store 17 42.28 63 3x16mm
2 LPP-F1-17
6.8
m18 Store 18 46.48 63 3x16mm
2 LPP-F1-18
6.8
m20 Store 20 7.48 10 3x2.5m
m2 LPP-F1-20
3.6
m21 Store 21 8.68 10 3x2.5m
m2 LPP-F1-21
3.6
m22 Store 22 7.48 10 3x2.5m
m2 LPP-F1-22
3.6
m19 Electrical
room 1 3.76 10
3x2.5mm2
LPP-F1-19
3.6
m27 Bathroom
1 20.58 25 3x4mm2
LPP-F1-27
4.6
m29 HALL1 1.33 10 2x2.5m
m2 3.6
m37 HALL5 2 10 2x2.5m
m2 3.6
m39 HALL6 1.48 10 2x2.5m
m2 3.6
m41 HALL7 1.33 10 2x2.5m
m2 3.6
m42 HALL8 1.625 10 2x2.5m
m2 3.6
m46
Entrance
8.18 10 2x2.5m
m2 3.6
m47 8.18 10 2x2.5m
m2 3.6
m48 Escalator
3 30.30
3 40
2x10mm2
5.8
CHAPTER 9 THE SHOPPING MALL
201
E L E C T R I C A L
R O O M
2
S M D B - F 2
m7 Store 7 3.71 10 3x2.5m
m2 LPP-F2-7
57.701 80A (3x25+16+16)
mm2
3.6
470.4
60
m8 Store 8 3.71 10 3x2.5m
m2 LPP-F2-8
3.6
m10 Store 10 5.19 10 3x2.5m
m2 LPP-F2-10
3.6
m11 Store 11 3.94 10 3x2.5m
m2 LPP-F2-11
3.6
m12 Store 12 5.19 10 3x2.5m
m2 LPP-F2-12
3.6
m13 Store 13 3.94 10 3x2.5m
m2 LPP-F2-13
3.6
m14 Store 14 4.59 10 3x2.5m
m2 LPP-F2-14
3.6
m15 Store 15 7.81 10 3x2.5m
m2 LPP-F2-15
3.6
m16 Store 16 42.28 63 3x16mm
2 LPP-F2-16
6.8
m23 Store 23 7.48 10 3x2.5m
m2 LPP-F2-23
3.6
m24 Store 24 5.73 10 3x2.5m
m2 LPP-F2-24
3.6
m25 Store 25 5.73 10 3x2.5m
m2 LPP-F2-25
3.6
m26 Store 26 7.48 10 3x2.5m
m2 LPP-F2-26
3.6
m9 Electrical
room 2 6.34 10
3x2.5mm2
LPP-F2-9
3.6
m28 Bathroom
2 20.58 25 3x4mm2
LPP-F2-28
4.6
m31 HALL2 3.045 10 2x2.5m
m2 3.6
m33 HALL3 1.48 10 2x2.5m
m2 3.6
m35 HALL4 1.625 10 2x2.5m
m2 3.6
m44 HALL9 2.95 10 2x2.5m
m2 3.6
m49 Escalator
4 30.30
3 40
2x10mm2
5.8
CHAPTER 9 THE SHOPPING MALL
202
9.3.5 First Floor Emergency Backup Scheme_
The shopping mall is equipped with an emergency backup electrical scheme to avoid mall blackout and
severe under voltage which could harm connected appliances.
During mall black out the emergency lighting will regain function after a limited time no more than 15
seconds which is the time taken by the emergency generator to start. The emergency lighting illuminates
the mall halls and exit stairs which facilitates the easy exit of customers and mall personnel.
The following table shows the emergency panel connected loads which mainly include 50% of Hall way
lighting providing illumination of 75 lux since the mall shops are not equipped with a backup lighting
plan, so this percentage of hallway lighting will provide enough illumination to assure both customer and
personnel safety.
Emergency Panel (Lighting :75 lux) EMDB-F
Place Line Line
current MCB Rating C.S.A
Main Panel
Current
Main MCB
Main CSA
Hall 1 m30e 1.33 10 2x2.5mm2
23.715 32A 2x6mm2
Hall 2 m32e 3.045 10 2x2.5mm2
Hall 3 m34e 1.48 10 2x2.5mm2
Hall 4 m36e 1.625 10 2x2.5mm2
Hall 5 m38e 2 10 2x2.5mm2
Hall 6 m40e 1.48 10 2x2.5mm2
Hall 8 m43e 1.625 10 2x2.5mm2
Hall 9 m45e 2.95 10 2x2.5mm2
Bathroom1 lighting
m50e 1.14 10 2x2.5mm2
Bathroom1 lighting
m51e 1.14 10 2x2.5mm2
Electrical Room 1
m52e 4.1 10 2x2.5mm2
Electrical Room 2
m53e 1.8 10 2x2.5mm2
CHAPTER 9 THE SHOPPING MALL
203
CHAPTER 9 THE SHOPPING MALL
204
9.4 Second Floor_
9.4.1 Second Floor Lighting Calculations_
The lighting calculations are done on basis of 300 lux for stores and 150 lux for hall
ways and stairs. Also a utilization factor of 0.66 and a maintenance factor of 0.8
according to a weekly mall cleaning basis
The used equation is: ๐(๐๐ข๐๐๐๐ ๐๐ ๐๐๐๐๐ ) =๐ธโ๐ด
๐ขโ๐โฮท
Place Lux Area U m efficacy
(ศ ) lamp
Power number of lamps
installed number
of lamps
installed wattage
power factor
lamp current
lines
shop 1 300 103.84 0.66 0.8 35 52 32.4168 36 1872 0.8 10.63636 1 , 2
projector 1 150 25.44 0.58 0.8 35 52 4.51876 5 260 0.8 1.477273 3
cinema 1 120 158.03 0.58 0.6 18.6 50 58.5929 70 3500 1 15.90909 4,5,6
cinema 1 0 60 16 16 960 1 4.363636 7
electric room 1
150 6.65 0.5 0.6 80 40 1.03906 2 80 0.8 0.454545 8
stairs 1 150 71.75 - - - - - - - - - -
pop corn 300 11.4 0.5 0.8 35 52 4.6978 6 312 0.8 1.772727 8
cinema hall 150 70.5 0.63 0.8 18.6 50 22.5614 21 1050 1 4.772727 8
information booth
300 16.8 0.5 0.8 80 40 3.9375 4 160 0.8 0.909091 9
bathroom1 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 9
bathroom2 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 9
cinema 2 120 157.29 0.58 0.6 18.6 50 58.3204 70 3500 1 15.90909 10,11,12
cinema 2 0 60 16 16 960 1 4.363636 13
projector 2 300 25.85 0.45 0.8 80 40 6.73177 6 240 0.8 1.363636 14
shop 2 300 153.12 0.66 0.8 35 52 47.8022 57 2964 0.8 16.84091 15,16,17
bathroom3 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 37
shop 3 300 28.49 0.58 0.8 35 52 10.121 10 520 0.8 2.954545 18
shop 4 300 14.06 0.58 0.6 35 52 6.65972 6 312 0.8 1.772727 19
shop 5 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 20
shop 6 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 21
shop 7 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 22
bathroom4 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 38
electric room 2
300 12.95 0.5 0.6 80 40 4.04688 4 160 0.8 0.909091 39
shop 8 300 12.92 0.58 0.8 35 52 4.58981 6 312 0.8 1.772727 23
shop 9 300 26.52 0.58 0.8 35 52 9.42118 12 624 0.8 3.545455 24
shop 10 300 12.92 0.58 0.8 35 52 4.58981 6 312 0.8 1.772727 25
shop 11 300 13.6 0.58 0.8 35 52 4.83138 7 364 0.8 2.068182 26
shop 12 300 52.5 0.63 0.8 35 52 17.1703 15 780 0.8 4.431818 27
CHAPTER 9 THE SHOPPING MALL
205
shop 13 300 126 0.66 0.8 35 52 39.3357 38 1976 0.8 11.22727 28,29
shop 14 300 20.35 0.58 0.8 35 52 7.2293 8 416 0.8 2.363636 30
shop 15 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 31
shop 16 300 20.35 0.58 0.8 35 52 7.2293 8 416 0.8 2.363636 32
shop 17 300 56 0.63 0.8 35 52 18.315 19 988 0.8 5.613636 33
shop 18 300 30 0.58 0.8 35 52 10.6574 10 520 0.8 2.954545 34
shop 19 300 30 0.58 0.8 35 52 10.6574 10 520 0.8 2.954545 35
shop 20 300 56 0.63 0.8 35 52 18.315 19 988 0.8 5.613636 36
corridor1 150 282 0.64 0.8 35 26 90.7881 75 1950 0.8 11.07955 40,41,42,43
corridor2 150 104.4 0.64 0.8 35 26 33.6109 38 988 0.8 5.613636 44,45
corridor3 150 169.09 0.64 0.8 35 26 54.4375 44 1144 0.8 6.5 46,47
corridor4 150 74.8 0.64 0.8 35 26 24.0814 22 572 0.8 3.25 48
corridor5 150 75.6 0.64 0.8 35 26 24.3389 22 572 0.8 3.25 49
main hall entrance
- 35 - - - 150 35 35 5250 0.8 29.82955 50,51,52,53,54
ticket booth 150 6 0.5 0.8 80 40 0.70313 2 80 0.8 0.454545 9
CHAPTER 9 THE SHOPPING MALL
206
CHAPTER 9 THE SHOPPING MALL
207
9.4.2 Second Floor Socket Calculations & Wiring_
Main Room Main
current
lighting
Line
lighting current
lighting C.B
lighting C.S.A
socket
line
Socket Line Type
No. of
sockets
socket
current
socket
C.B
sockets C.S.A
m1 shop 1 41.716
line 1
5.318 10 2*2.5 mm2
line 3
normal sockets
7 4.4 10 3*2.5 mm2
line 2
5.318 10 2*2.5 mm2
line 4
power socket
1 20 25 3*4
mm2
line
5 power socket
1 20 25 3*4
mm2
m21
projector 1
23.4202
line 1
1.4772 10 2*2.5 mm2
line 6
normal sockets
2 2.4 10 3*2.5 mm2
cinema 1
line 2
5.3 10 2*2.5 mm2
line 3
5.3 10 2*2.5 mm2
line 4
5.3 10 2*2.5 mm2
line 5
4.363 10 2*2.5 mm2
m41 electric room 1
2.1345 line
1 0.4545 10
2*2.5 mm2
line 2
normal sockets 3
2 2.4 10 3*2.5 mm2
m23
ticket booth
68.6
line 1
0.454 10 2*2.5 mm2
line 2
normal socket 31
3 2.8 10 3*2.5 mm2
pop corn
line 1
1.772 10 2*2.5 mm2
line 2
normal sockets 4
3 2.8 10 3*2.5 mm2
line
3 power
socket 3 1 20 25
3*4 mm2
cinema hall line
1 4.772 10
2*2.5 mm2
information booth
line 1
0.909090909
10 2*2.5 mm2
line 2
normal sockets 5
3 2.8 10 3*2.5 mm2
bathroom1
line 1
1.363 10 2*2.5 mm2
line 2
normal sockets 6
2 2.4 10 3*2.5 mm2
line
3 power
socket 4 1 25 25
3*4 mm2
bathroom2
line 1
1.363 10 2*2.5 mm2
line 2
normal sockets 7
2 2.4 10 3*2.5 mm2
line
3 power
socket 5 1 25 25
3*4 mm2
m22
cinema 2
20.672
line 1
5.3 10 2*2.5 mm2
line 2
5.3 10 2*2.5 mm2
line 3
5.3 10 2*2.5 mm2
line 4
4.772 10 2*2.5 mm2
projector 2 line
5 1.363 10
2*2.5 mm2
line 6
normal sockets 8
3 2.8 10 3*2.5 mm2
m2 shop 2 61.639
line 1
5.613 10 2*2.5 mm2
line 4
normal sockets 9
6 4 10 3*2.5 mm2
line 2
5.613 10 2*2.5 mm2
line 5
power socket 6
1 20 25 3*4
mm2
line 3
5.613 10 2*2.5 mm2
line 6
power socket 7
1 20 25 3*4
mm2
line
7 power
socket 8 1 20 25
3*4 mm2
m43 bathroom3 20.543 line 1.363 10 2*2.5 line normal 2 2.4 10 3*2.5
CHAPTER 9 THE SHOPPING MALL
208
1 mm2 2 sockets 10 mm2
line
3 power
socket 9 1 25 25
3*4 mm2
m3 shop 3 5.474 line
1 2.954 10
2*2.5 mm2
line 2
normal sockets 11
5 3.6 10 3*2.5 mm2
m4 shop 4 4.012727273
line 1
1.772727273
10 2*2.5 mm2
line 2
normal sockets 12
4 3.2 10 3*2.5 mm2
m5 shop 5 4.012727273
line 1
1.772727273
10 2*2.5 mm2
line 2
normal sockets 13
4 3.2 10 3*2.5 mm2
m6 shop 6 4.012727273
line 1
1.772727273
10 2*2.5 mm2
line 2
normal sockets 14
4 3.2 10 3*2.5 mm2
m7 shop 7 4.012727273
line 1
1.772727273
10 2*2.5 mm2
line 2
normal sockets 15
4 3.2 10 3*2.5 mm2
m44 bathroom4 20.543
line 1
1.363 10 2*2.5 mm2
line 2
normal sockets 16
2 2.4 10 3*2.5 mm2
line
3 power
socket 10 1 25 25
3*4 mm2
m42 electric room 2
2.869 line
1 0.909 10
2*2.5 mm2
line 2
normal sockets 17
3 2.8 10 3*2.5 mm2
m8 shop 8 3.732 line
1 1.772 10
2*2.5 mm2
line 2
normal sockets 18
3 2.8 10 3*2.5 mm2
m9 shop 9 6.06 line
1 3.54 10
2*2.5 mm2
line 2
normal sockets 19
5 3.6 10 3*2.5 mm2
m10 shop 10 3.732 line
1 1.772 10
2*2.5 mm2
line 2
normal sockets 20
3 2.8 10 3*2.5 mm2
m11 shop 11 4.308 line
1 2.068 10
2*2.5 mm2
line 2
normal sockets 21
4 3.2 10 3*2.5 mm2
m12 shop 12 7.51 line
1 4.43 10
2*2.5 mm2
line 2
normal sockets 22
7 4.4 10 3*2.5 mm2
m13 shop 13 42.307
line 1
5.6135 10 2*2.5 mm2
line 3
normal sockets 23
7 4.4 10 3*2.5 mm2
line 2
5.6135 10 2*2.5 mm2
line 4
power sockets 11
1 20 25 3*4
mm2
2*2.5 mm2
line 5
power sockets 12
1 20 25 3*4
mm2
m14 shop 14 4.603 line
1 2.363 10
2*2.5 mm2
line 2
normal sockets 24
4 3.2 10 3*2.5 mm2
m15 shop 15 4.012 line
1 1.772 10
2*2.5 mm2
line 2
normal sockets 25
4 3.2 10 3*2.5 mm2
m16 shop 16 5.163 line
1 2.363 10
2*2.5 mm2
line 2
normal sockets 26
6 4 10 3*2.5 mm2
m17 shop 17 8.413636364
line 1
5.613636364
10 2*2.5 mm2
line 2
normal sockets 27
6 4 10 3*2.5 mm2
m18 shop 18 6.03 line
1 2.95 10
2*2.5 mm2
line 2
normal sockets 28
7 4.4 10 3*2.5 mm2
m19 shop 19 6.03 line
1 2.95 10
2*2.5 mm2
line 2
normal sockets 29
7 4.4 10 3*2.5 mm2
m20 shop 20 8.693636364
line 1
5.613636364
10 2*2.5 mm2
line 2
normal sockets 30
7 4.4 10 3*2.5 mm2
m24
corridor1
2.77 line
1 5.539 10
2*2.5 mm2
m25 2.77 line
2 5.539 10
2*2.5 mm2
m26 2.77 line
3 5.539 10
2*2.5 mm2
m27 2.77 line
4 5.539 10
2*2.5 mm2
m28
corridor2
2.807 line
1 2.807 10
2*2.5 mm2
m29 2.807 line
2 2.807 10
2*2.5 mm2
m30 corridor3 3.25 line
1 3.25 10
2*2.5 mm2
CHAPTER 9 THE SHOPPING MALL
209
m31 3.25 line
2 3.25 10
2*2.5 mm2
m32
corridor4
1.625 line
1 1.625 10
2*2.5 mm2
m33 1.625 line
2 1.625 10
2*2.5 mm2
m34
corridor5
1.625 line
1 1.625 10
2*2.5 mm2
m35 1.625 line
2 1.625 10
2*2.5 mm2
m36
main hall entrance
5.964 line
1 5.964 10
2*2.5 mm2
m37 5.964 line
2 5.964 10
2*2.5 mm2
m38 5.964 line
3 5.964 10
2*2.5 mm2
m39 5.964 line
4 5.964 10
2*2.5 mm2
m40 5.964 line
5 5.964 10
2*2.5 mm2
9.4.3 Second Floor Local Feeders_
Line Room Current MCB C.S.A (1ph+n+e)
m1 shop 1 41.7 63 3x10mm2
m21 projector 1
23.4202 25 3x4mm2 cinema 1
m41 electric room 1 2.2254 10 3x2.5mm2
m23
ticket booth
68.6 80 3x25mm2
pop corn
cinema hall
information booth
bathroom1
bathroom2
m22 cinema 2
20.672 25 3x4mm2 projector 2
m2 shop 2 61.639 63 3x10mm2
m43 bathroom3 20.543 25 3x4mm2
m3 shop 3 5.474 10 3x2.5mm2
m4 shop 4 4.012727273 10 3x2.5mm2
m5 shop 5 4.012727273 10 3x2.5mm2
m6 shop 6 4.012727273 10 3x2.5mm2
m7 shop 7 4.012727273 10 3x2.5mm2
CHAPTER 9 THE SHOPPING MALL
210
m44 bathroom4 20.543 25 3x4mm2
m42 electric room 2 2.869 10 3x2.5mm2
m8 shop 8 3.732 10 3x2.5mm2
m9 shop 9 6.06 10 3x2.5mm2
m10 shop 10 3.732 10 3x2.5mm2
m11 shop 11 4.308 10 3x2.5mm2
m12 shop 12 7.51 10 3x2.5mm2
m13 shop 13 42.307 63 3x10mm2
m14 shop 14 4.603 10 3x2.5mm2
m15 shop 15 4.012 10 3x2.5mm2
m16 shop 16 5.163 10 3x2.5mm2
m17 shop 17 8.413636364 10 3x2.5mm2
m18 shop 18 6.03 10 3x2.5mm2
m19 shop 19 6.03 10 3x2.5mm2
m20 shop 20 8.693636364 10 3x2.5mm2
m24
corridor1
2.77 10 2x2.5mm2
m25 2.77 10 2x2.5mm2
m26 2.77 10 2x2.5mm2
m27 2.77 10 2x2.5mm2
m28 corridor2
2.807 10 2x2.5mm2
m29 2.807 10 2x2.5mm2
m30 corridor3
3.25 10 2x2.5mm2
m31 3.25 10 2x2.5mm2
m32 corridor4
1.625 10 2x2.5mm2
m33 1.625 10 2x2.5mm2
m34 corridor5
1.625 10 2x2.5mm2
m35 1.625 10 2x2.5mm2
m36
main hall entrance
5.964 10 2x2.5mm2
m37 5.964 10 2x2.5mm2
m38 5.964 10 2x2.5mm2
m39 5.964 10 2x2.5mm2
m40 5.964 10 2x2.5mm2
CHAPTER 9 THE SHOPPING MALL
211
9.4.4 Second Floor SMDBs_& Cable Tray Dimension_
It should be noted that each floor contains 2 electrical rooms, the first electrical
room consists of one service panel board "SMDB-S1" where the S indicates that this
panel board is in the second floor and the numeral 1 indicates that this service panel is
located in the electrical room 1.The first electrical room also contains an emergency
panel board "EMDB-S". The second electrical room consists of only one service panel
"SMDB-S2". The service and emergency panel's enclosures are compliant with the
standards "service enclosure Ip40 (NEMA1)"
Line Room Curren
t
M C B
C.S.A (1ph+n+e)
Panel Code
Service Panel Main
current (per
phase)
Service
Panel 3ph
MCCB Rating
Service Panel Incoming Cable
(3ph+n+e)
Cable Overall Diamet
er
Cable
Tray Widt
h (mm)
Installed
Cable Tray
Width (cm)
E L E C T R I C A L
R O O M 1
S M D B - S 1
M 1
shop 1 41.7 63 3x10mm2 LPP-S1-1
88.22053333
100A (3x35+16+16)
mm2
5.8
391.2
50
m2 shop 2 61.63
9 63 3x10mm2 LPP-S1-2 5.8
m14 shop 14 4.603 10 3x2.5mm2 LPP-S1-14 3.6
m15 shop 15 4.012 10 3x2.5mm2 LPP-S1-15 3.6
m16 shop 16 5.163 10 3x2.5mm2 LPP-S1-16 3.6
m21
projector 1 23.42
02 25 3x4mm2 LPP-S1-21 4.6
cinema 1
m22
cinema 2 20.67
2 25 3x4mm2 LPP-S1-22 4.6 projector
2
m23
ticket booth
68.6 80 3x25mm2 LPP-S1-23 8.4
pop corn
cinema hall
information booth
bathroom1
bathroom2
m28 corridor2 2.807 10 2x2.5mm2 3.6
m36
main hall entrance
5.964 10 2x2.5mm2 3.6
m37 5.964 10 2x2.5mm2 3.6
m38 5.964 10 2x2.5mm2 3.6
m39 5.964 10 2x2.5mm2 3.6
m40 5.964 10 2x2.5mm2 3.6
m41 electric room 1
2.2254
10 3x2.5mm2 LPP-S1-41 3.6
CHAPTER 9 THE SHOPPING MALL
212
E L E C T R I C A L
R O O M 2
S M D B - S 2
m3 shop 3 5.474 10 3x2.5mm2 LPP-S2-3
58.11206061
80A (3x25+16+16)
mm2
3.6
522 60
m4 shop 4 4.012727
10 3x2.5mm2 LPP-S2-4 3.6
m5 shop 5 4.012727
10 3x2.5mm2 LPP-S2-5 3.6
m6 shop 6 4.012727
10 3x2.5mm2 LPP-S2-6 3.6
m7 shop 7 4.012727
10 3x2.5mm2 LPP-S2-7 3.6
m8 shop 8 3.732 10 3x2.5mm2 LPP-S2-8 3.6
m9 shop 9 6.06 10 3x2.5mm2 LPP-S2-9 3.6
m10 shop 10 3.732 10 3x2.5mm2 LPP-S2-10 3.6
m11 shop 11 4.308 10 3x2.5mm2 LPP-S2-11 3.6
m12 shop 12 7.51 10 3x2.5mm2 LPP-S2-12 3.6
m13 shop 13 42.30
7 63 3x10mm2 LPP-S2-13 5.8
m17 shop 17 8.413636
10 3x2.5mm2 LPP-S2-17 3.6
m18 shop 18 6.03 10 3x2.5mm2 LPP-S2-18 3.6
m19 shop 19 6.03 10 3x2.5mm2 LPP-S2-19 3.6
m20 shop 20 8.693636
10 3x2.5mm2 LPP-S2-20 3.6
m24 corridor1
2.77 10 2x2.5mm2 3.6
m26 2.77 10 2x2.5mm2 3.6
m30 corridor3 3.25 10 2x2.5mm2 3.6
m32 corridor4 1.625 10 2x2.5mm2 3.6
m34 corridor5 1.625 10 2x2.5mm2 3.6
m43 bathroom
3 20.54
3 25 3x4mm2 4.6
m44 bathroom
4 20.54
3 25 3x4mm2 4.6
m42 electric room 2
2.869 10 3x2.5mm2 LPP-S2-42 3.6
CHAPTER 9 THE SHOPPING MALL
213
9.4.5 Second Floor Emergency Backup Scheme_
The shopping mall is equipped with an emergency backup electrical scheme to avoid mall blackout and
severe under voltage which could harm connected appliances.
During mall black out the emergency lighting will regain function after a limited time no more than 15
seconds which is the time taken by the emergency generator to start. The emergency lighting illuminates
the mall halls and exit stairs which facilitates the easy exit of customers and mall personnel.
The following table shows the emergency panel connected loads which mainly include 50% of Hall way
lighting providing illumination of 75 lux since the mall shops are not equipped with a backup lighting
plan, so this percentage of hallway lighting will provide enough illumination to assure both customer and
personnel safety.
Emergency Panel (Lighting :75 lux) EMDB-S
Place Line Line
current MCB Rating C.S.A
Main Panel
Current
Main MCB
Main CSA
Corridor 1 m25e 2.77 10 2x2.5mm2
32.206 40A 2x10mm2
m27e 2.77 10 2x2.5mm2
Corridor 2 m29e 2.807 10 2x2.5mm2
Corridor 3 m31e 3.25 10 2x2.5mm2
Corridor 4 m33e 1.625 10 2x2.5mm2
Corridor 5 m35e 1.625 10 2x2.5mm2
Cinema 1 m45e 8 20 2x4mm2
Cinema 2 m46e 8 20 2x4mm2
Electrical Room 1
m47e 0.45
10 2x2.5mm2
Electrical Room 2
m48e 0.909 10 2x2.5mm2
CHAPTER 9 THE SHOPPING MALL
214
CHAPTER 9 THE SHOPPING MALL
215
9.5 Air Conditioner and Elevator Panel (Roof Panel) _
The air conditioning scheme of the mall is composed of 15 shellers, each with an
expected current of 154.988 which is based on the approximate prediction of
mechanical engineers which is 600 KVA for the whole mall.
Roof Panel (SMDB-R)
Line Room Current MCCB &
MCB C.S.A
Service Panel Main current (per
phase)
Service Panel 3ph
MCCB Rating
Service Panel Incoming Cable
(3ph+n+e)
m1
Air Cond.
154.988 200 2x95mm2
547.7593333 630A (3x300+150)mm2
m2 154.988 200 2x95mm2
m3 154.988 200 2x95mm2
m4 154.988 200 2x95mm2
m5 154.988 200 2x95mm2
m6 154.988 200 2x95mm2
m7 154.988 200 2x95mm2
m8 154.988 200 2x95mm2
m9 154.988 200 2x95mm2
m10 154.988 200 2x95mm2
m11 154.988 200 2x95mm2
m12 154.988 200 2x95mm2
m13 154.988 200 2x95mm2
m14 154.988 200 2x95mm2
m15 154.988 200 2x95mm2
m16 Elevator 22.72 32 2x6mm2
9.6 Mall Panel Boards Connection Diagram & Cable Specifications_
Mall Cables are based on two types of cables which lay in two parts. The first type
of chosen cables is 450/750 Volts PVC 85"C insulated with copper conductor Single
core Solid or Stranded Up to 6 mm2 and Stranded up to 630 mm2, this type is used
for the connections between the floor service panels and the "SMDB's" and mall loads
which are represented in floor lighting and store feeders. The second type of cables is
600/1000 Volts Single core (cu) PVC 85"C insulation - PVC sheath, this type is used
in the rest of the mall wiring as shown in the diagram, it should also be noted that
cables are placed in cable trays and an assumptions is made that the cable is exposed
to the worst possible conditions when using the cable tables to provide us with a good
safety margin.
CHAPTER 9 THE SHOPPING MALL
216
Panel Current (per
phase) MCCB (3-
ph) Riser CSA (3ph+n+e)
Mall Current (per phase)
MCCB (3ph)
Mall Feeder
ER's 1 PB 270.65 320A (3x240+120+120)mm2
1032.239333 1600A 4x(3x300+150)
ER's 2 PB 180.99 200A (3x120+70+70)mm2
SMDB-R 547.7593333 630A (3x300+150)mm2
E-Panel 32.84 80A (3x25+16)mm2
SPARE 320 (3x240+120+120)mm2
CHAPTER 9 THE SHOPPING MALL
217
CHAPTER 9 THE SHOPPING MALL
218
9.7 Detailed Single Line Diagram of Each Panel Board_
CHAPTER 9 THE SHOPPING MALL
219
9.7.1 Electrical Rooms 1 Panel Boards_
CHAPTER 9 THE SHOPPING MALL
220
9.7.2 Electrical Rooms 2 Panel Boards_
CHAPTER 9 THE SHOPPING MALL
221
9.7.3 Emergency Panel Boards_
CHAPTER 9 THE SHOPPING MALL
222
9.8 Emergency Operation_
In case of a black out or a fault ,safety must be provided for both customers and mall
personnel so we built our emergency operation scheme on basis of immediate
evacuation of the mall during black out, so we provided emergency illumination for
hallways and stairs ,also an emergency cable was provided to the cinema in order to
insure the safe evacuation of cinema viewers in case of occurrence of a blackout .The
emergency hallways' illumination is 75 lux which is very sufficient for evacuation
keeping in mind that stores' emergency plan is left to their decision in this matter, so
as a worst case scenario that store owners donโt equip their stores with a back up
electrical plan ,we provided sufficient illumination in the hallways ,which is 50% of
normal hallway illumination.
9.8.1 ATS specifications_
The used ATS in the Mall is of the brand "ZTE Automatic Transfer Switches". The
chosen standard is "Standard Open Transition" which is characterized by double
throw, solenoid operated, Break-before-Make mechanism. The chosen ATS rating is
100A which can transfer 66KVA which is very sufficient for our emergency loads
which are 21.67 KVA. This margin is chosen in order to accommodate any future
loadings on the emergency scheme.
The automatic transfer switch continually monitors the incoming utility power. Any
anomalies such as voltage sags, brownouts, spikes, or surges will cause the internal
circuitry to command a generator to start and will then transfer to the generator when
additional switch circuitry determines the generator has the proper voltage and
frequency. When utility power returns or no anomalies have occurred for a set time,
the transfer switch will then transfer back to utility power and command the generator
to turn off, after another specified amount of "cool down" time with no load on the
generator.
9.8.2 Emergency Generator_
The Chosen generator rating is 50 KVA which is more than double the current
emergency load in order to accommodate any future loading on the emergency
scheme.