substation designing- gis

7/27/2019 Substation Designing- GIS

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REPORT

66/33/11 kV Substation Design Report

Northern Region, GreaterNoida(GIS Substation)

Abstract-This report outlines the need of the GIS

technology integration in the power system in areas

like GREATER NOIDA, It gives a study reportregarding an installation of distribution GIS

substation. The report includes space consideration

with other technical information of substation

erection.

I. SITE PROFILE

Greater Noida or new Okhla industrial

development area are came into being as Industrial

Township in 1976 catering to Delhis commercial

needs and addressing its concern over polluting

industries. Greater Noida is the Planning Marveland an emerging Dream Township. The Total

Notified Area: 36,000 hectares Already urbanized

in Phase I: 5,000 hectares Organisable area: 12,000

hectares (by 2011) City planned for a population

of: 0.7 million (by 2011) & 1.2 million (by 2021)

Industry led development: 3000 hectares (to be

developed by 2011) Strategic Location within NCR

* Well linked to domestic & international markets.

The year 2010-11 proved to be a bad year

for industrial development in Noida and Greater

Noida. A total of 319 units shut operations during

the last financial year, more than 50% up from the

figure of 205 a year ago. Also, in 2009-10, a totalof 1,610 new units came up. But in the last

financial year, only 1,360 units were set up. Poor

power supply and deteriorating law and order

situation remained the main issue.

Greater Noida Industrial Development

Authority falls within the National Capital Region

of Indias capital - New Delhi and is adjacent to

Noida, one of the largest industrial townships in

Asia. It conceptualizes the needs of a fast

developing city of the future. The Action Plan and

execution is at par with global standards and is

aimed at accelerating the growth of industrial, IT

and institutional sectors in the country.Ecotech is

Greater Noida's exclusive Industrial area..Industrial

investment taking place in Greater Noida is now

over Rs. 10,000 crores. It has now become one of

the favoured locations for good industrial

investment especially of multinational investment

because of its good infrastructure near Delhi and

effective single window system of speedy decision

making and clearances.

To sustain this increase in demand of

power consumption more and more challenges are

faced by the government authorities to maintain the

power quality and integration of new technologies

in the power system to make it more reliable. As a

part of this problem substation technologies have

come up with up gradation from Air Insulated

substation to the GIS (Gas Insulated Substation).

Gas insulated switchgear (GIS) is a proven

technology used throughout the world that offers

many advantages over a conventional substation. A

primary advantage is its compactness, which allows

a GIS to be placed closer to a load centre, and it ismore aesthetically attractive, resulting in quicker

installation time, reduced maintenance, higher

reliability and safety, and excellent ability to

withstand seismic events.

When all these advantages are taken into

consideration, a gas-insulated substation is a cost-

effective to a convention in an urban community

and NOIDA region also demand such new

technologies to be implemented considering the

rate of the industrialisation and urbanisation.

The problem of power quality has been a

major threat, causing interruption of supply and

voltage sags which ultimately have led to declining

production and profitability of the industries. As

the reference of this background Uttar Pradesh

Power Corporation Limited (UPPCL) has proposed

many GIS substation to be installed and one of

them is being decided to be erected at the

GREATER NOIDA which takes power from the

substation PALI located about 30km. PALI

substation draws power from the generation plant

650 km far situated at Rihand Thermal power plant


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Fig 1: Single Line Diagram of Proposed GIS substation:


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II.LAYOUT AND DESIGN CONEPT

The proposed substation is connected to

Pali substation and draws power at 66kV and fed

power with in all four outgoing feeders with

voltage levels 33kV and 11kV.The proposed layout

is given in Fig. 1.The specification covers scope of

design, electrical specification of the components

used, monitoring system, safety and precaution

standards considering the climatic condition of the

site. It is desirable to have the INDOOR gis

considering the scarcity of land and also the high

cost of the land. The scope also covers provision of

modular design considering future expansion in the

load demand.

A. Material and design

Aluminium or aluminium alloys shall be

used preferably for the enclosures. The material

and thickness of the enclosure shall be selected to

withstand an internal arc and to prevent a burn-

through or puncturing of the housing within thefirst stage of protection, referred to a short-circuit

current of 40 kA.

For supervision of the gas within the

enclosures, density monitors with electrical

contacts for at least two pressure levels shall be

installed. The circuit-breakers, however, might be

monitored by density gauges fitted in circuit-

breaker control units.

The manufacturer assures that the pressure

loss within each individual gas compartment and

not referred to the total switchgear installation only

will be not more than 1% per year per gascompartment.Each gas-filled compartment shall be

equipped with static filters of a capacity to absorb

any water vapour penetrating into the switchgear

installation over a period of at least 25 years.

B. SF6

Sulphur hexafluoride is an inert, nontoxic,

colourless, odourless, tasteless, and non-flammable

gas consisting of a sulphur atom surrounded by and

tightly bonded to six fluorine atoms. It is about five

times as dense as air. SF6 is about 100 times better

than air for interrupting arcs.

SF6 is a strong greenhouse gas that couldcontribute to global warming. At an international

treaty conference in Kyoto in 1997, SF6 was listed

as one of the six greenhouse gases whose emissions

should be reduced. Field checks of GIS in service

for many years indicate that the leak rate objective

can be as low as 0.1% per year when GIS standards

are revised.

Fig. 2 GIS assembly

C. Circuit Breaker

GIS uses dead tank SF6 puffer circuit

breakers. The nozzles on the circuit breaker

enclosure are directly connected to the adjacent

GIS module. Enclosure material will be aluminium

alloy.Circuit breakers are equipped with self-blast

interrupters. require minimum maintenance and

only a low amount of switching energy.

Table No.1

(High voltage Alternating current circuit breakers: IEC

62271-100)

1 Rated voltage 72.5 kV

2 Rated current 1600A

3 Rated frequency 50Hz

4 Rated short-circuit breaking current 25 kA rms,3 sec

5 Rated break-time 3 cycle

6 Rated short-circuit making current 62.5 kA peak

D. Disconnector (Isolator)

Disconnect switches have a moving

contact that opens or closes a gap between

stationary contacts when activated by an insulating

operating rod that is itself moved by a sealed shaft

coming through the enclosure wall. The moving

contact velocity is relatively low and the disconnect

switch can interrupt only low levels of capacitive

current or small inductive currents.


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Table No.2

(Alternating current Disconnector (isolators) and earthingSwitch IEC 62271-102)

1 Rated voltage 72.5 kV

2 Rated current 1600 A

3 Rated short-time current 25 kA rms, 3 sec

4 Rated control and operatingvoltage 110/220 V DC

5 Type of operating mechanism Motor operated

Mechanically gangedOperated

6 Rated insulation level

a Power frequency withstand

voltage- phase to phase, between phases

rms

- Across the isolating distance

140 kV160 kV rms

b Lightning impulse withstandvoltage

- phase to phase, between phases

350 kV peak

E. High Speed Earthing Switch

(IEC 62271102 class B) as mentioned above.

Fast acting grounding switches shall be of

three phase, encapsulated, three phase linkage

group operated by a maintenance-free self-

contained electrical motor. They shall also have

facilities for emergency manual operation and the

necessary operating handles or hand cranks shall be

supplied.DC motor operation (220 V) completely

suitable for remoteoperation and a manual

emergency drivemechanism is required.

F. Maintenance Earthing Switch

(IEC 62271102 class B) as mentioned above.

G. Current Transformers

CTs are inductive ring types installed

inside the GIS enclosure. The GIS conductor is the

single turn primary for the CT. CTs inside the

enclosure are shielded from the electric field

produced by the high voltage conductor or high

transient voltages can appear on the secondary

through capacitive coupling.

Table No.3

H. Voltage Transformers

VTs are inductive types with an iron core.

The primary winding is supported on an insulating

plastic film immersed in SF6. The VT has an

electric field shield between the primary and

secondary windings to prevent capacitive coupling

of transient voltages.

(IEC 60044)

Table No.4

1 Rated voltage 66kV

2 Highest system voltage 72.5kV

3 Rated frequency 50Hz

4 P F(dry) withstand voltage 140kV

5 Voltage factor 1.2 continuous

6 1.2/50 micro sec. lightningimpulse withstand voltage

350kVp

7 Grounding Effective

I.Bus

To connect GIS modules that are not

directly connected to each other, an SF6 busconsisting of an inner conductor and outer

enclosure is used. Support insulators, sliding

electrical contacts, and flanged enclosure joints are

usually the same as for the GIS modules.

J. Bushings

Outdoor bushings shall be provided for

connection of conventional external conductors to

SF6 GIS. Suitable clamp & connectors shall be

supplied with bushing. The dimensional and

clearance requirements for the metal clad enclosure

shall be maintained as per requirement of relevant

standards.Only SF6 insulated composite silicon

bushings will be provided. The terminals on the

outdoor bushings shall be a solid stem with

dimensions specified.

K. GIS Connection

x Gis to transformerTransformers will be connected to the GIS by

termination of 66 kV XLPE power cable. The

connection between GIS and high voltage cable at

GIS end will be done through cable termination /

cable sealing end. For transformer end connection

the cable termination on structure shall be provided

outdoor. The plug in cable sealing ends for XLPEcables will consist of gas tight plug in sockets and

prefabricated plugs with grading elements of

silicone rubber.

x Gis to lineThe 66 kV line will be terminated to GIS by XLPE

power cable.

x 66 kV Power Cable connection


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The connection between GIS and high voltage

cable at GIS end is done through cable termination

/ cable sealing end. Plug in cable sealing ends for

XLPE cables will consist of gas tight plug in

sockets, and prefabricated plugs with grading

elements of silicone rubber. A separate cable

basement is provided for cable entry, its

distribution and installation. All end cable moduleswill be suitable for connecting single core, XLPE

specified cable.

L. Metal-Enclosed Surge Arresters

The 60 kV, hermetically sealed, Gapless,

ZnO, Surge arrestor, suitable for use with GIS. for

each phase, at the 66 kV line underground cable

entry terminals of GIS shall be provided, if

indicated in Schedule of requirements. Each Surge

Arrester shall be provided with self-leakage current

monitoring device at convenient elevation.

M.Power Transformer

Type and Ratings:

x Max. Continuous capacity:ONAF 20 MVA

x Number of phases 3x Frequency 50 Hz(5%)x Rated Voltage :HV side 66kV

LV side 33kV

x Connections :HV side StarLV side Star

x ON load taps on HV side+5% to -15% in steps of 1.25% each

Table No. 5

Insulation Level 66kV 33kV

i)Lightning

withstand

325kV 170kV

ii)Power frequencywithstand voltage

140kV(rms)

70kV(rms)

Insulation level of

Bushing

i)Lightningimpulse voltage 325 kV 170 kV

ii)Power frequency

voltage

140kV

(rms)

70kV

(rms)

III. MONITERING

A. Gas monitoring unit

Gas density or pressure monitoring

devices shall be provided for each gas

compartment. The devices shall provide continuous

and automatic monitoring of the state of the gas.

The SF6 gas monitoring device shall have two

supervision and alarm settings.After an urgent

alarm, operative measures can be taken to

immediately isolate the particular compartment

electrically by tripping circuit breakers and opening

Disconnector.

The gas monitoring device shall monitor at least the

following, locally and on remote.

i) "Gas Refill" Level- This will be used to

annunciate the need for gas refilling.

ii) "Breaker Block" Level- This is the minimum gas

density at which the manufacturer will guarantee

the rated fault interrupting capability of the breaker.

At this level the device contact shall trip the

breaker and block the closing circuits.

iii) Over pressure alarm level- This alarm level

shall be provided to indicate abnormal pressure rise

in the gas compartment. It shall be possible to testall gas monitoring relays without de-energizing the

primary equipment and without reducing pressure

in the main section. Each gas zone shall be

furnished with a gas monitoring system consisting

of a gas density continuous monitoring device

provided with two electrically independent contacts

which operate in two stages as follows:

a) First alarm: At a gas density normally 5 to 10%

below the nominal fill density.

b) Second alarm: Minimum gas density to achieve

equipment ratings.

In special cases determined by the supplier, a third

stage with a set of contacts may be necessary in

certain areas. It shall be ensured that there is no

chance of the gas liquefying at the lowest ambient

temperature

B. Local monitoring unit

a) The operator must be forced in to the only safe

and logical sequence to actuate the circuit breakers,

Disconnector&earthing switches.

b) The actual, completely closed or completely

opened position of all switching devices must be

checked before and after each move.

c) Implementation of logic checks and issuing the

resultant signals

The bursting pressure of relief device should be

effectively coordinated with the rated gas pressure

and the pressure rise due to arcing.

x Dew point measurement meterx SF6 gas leakage detector


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x Precision pressure gaugex Gas-service cartsx Any other special tool/tackle required.

C.Indicating Devices

Position indicators shall be provided to clearly

indicate whether a circuit-breaker is open or closed.Each circuit-breaker shall be provided with an

operation counter to record the number of tripping

operations performed.

D. Timing Test

Timing tests are to be carried out after the switch

gear has been completely charged with SF6 gas.

Testing instruments

x Air / gas humidity tester,x Gas purity detector for SO2, H2O, CF4,

AIR etc.,

x Gas leakage tester,x Breaker timing measurement kit,x Set of equipment for pressure

measurement and gas density meter.

Timing test facility shall be provided with

switchgear such that it is not necessary to

open up any gas section to make test

connections to the circuit breaker

terminals.

E.SCADA

The technologies developed are ranging from the

actual building and integrated SCADA based

monitoring system, through the compact gas-insulated Switchgear and transformers with

integrated control and protection equipment to the

SF6 Gas Management Plan (GMP) built around the

world. With all incoming and outgoing feeders

taking the form of cables, the building has no high

voltage-carrying elements on its outer walls.

IV. MODERN TECHNIQUES

1.Innovative and safe circuit breaker technology

requiring minimum space. The circuit breaker can

therefore be designed quite simple and reliable.

Interrupting unit based on the self blast principle

and hydromechanical spring operating mechanism

for a reactionless, reliable switching with soft

extinction behavior.

2.Integrated technology

Two different types of enclosures are available to

integrate the combined disconnector and earthing

switch into the building block system.

3.Busbardisconnector and earthing switch module

The busbar module of the combined disconnector

and earthing switch contains the busbar conductors

and in addition thereto a transversal arranged three

position switch..

4.Digital control and protection

. In case of digital control technology, the single

line diagram with position indicators and control

buttons is replaced by a digital human-machine

interface. Digital control devices provide the same

functions as conventional control technology.

Furthermore a lot of versatile, additional control

and protection functions can be implemented:

Synchro-check,Auto re-closing Operating

frequency supervision, Fault recorder, Backup

protection

5.Connection to station control

Communication between bay devices and the

device on

station level uses solely the new standardized

communication protocol

6.Digital monitoring systems

Either the conventional or the digital control

technology is completed by digital monitoring

systems. These systems operate as an add-on to the

existing control technology and do not interact with

the switchgear protection.

Monitoring systems improve the overall

availability by continuous supervision of all vital

functions of the switchgear. This ensures an earlydetection of critical situations and scheduling of

countermeasures into non-critical times.

7.A new way of Testing Gas Insulated Switchgear:

A voltage withstand test is necessary during the

commissioning of gas insulated high-voltage

switchgear (GIS). To date, the test was performed

by connecting a high-voltage test transformer and a

heavy control unit to the GIS. New technology

combines the multi-functional primary test system

CPC 100 with the newly developed CP RC

package, Together, they form a resonantcircuit..The package is connected to a voltage

transformer, which is specially designed for this

purpose .

8.Digital Relay:

Modern digital relays can be used for control as

well as for protection and other secondary

functions. Because of this, it is possible to group


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and combine different functions using just software

tools. Increased availability through self

supervision and selfchecking of the electronics for

the remaining hardwired connections

V. GROUNDING

GIS are subjected to the same magnitude of

ground fault current and require the same low-

impedance grounding as conventional substation. a

strong grounding system is necessary.

Material used:

Copper-clad steel

Copper is a common material used for grounding.

Copper conductors, in addition to their high

conductivity.

Size of conductor-6AWG

Area of grounding earth mat-40ft x 60ft

Equipments used:

1. grounding connectors Connecting all GIS

equipment, Bus duct, enclosures, control cabinets

supporting structures etc. To the ground bus of GIS

2.Connecting ground bus of GIS to the ground mat

riser.-GIS is housed on GIS floor. There will be

under-ground mat below the substation. There will

be adequate number of Galvanized steel risers to be

connected to grounding mat.

Enclosures and circulating currents:

the continuous-type enclosures provide a return

path for induced currents so that the conductor and

enclosure form a concentric pair with effective

external shielding of the field internal to the

enclosure

To limit the undesirable effects caused by

circulating currents, The possible solutions to

reduce the earth electrode resistance are taken as:

1. Use of High density grid:

2.Connection to the reinforced concrete mat:.

3.Use of deep driven ground rods

The following points will be considered:

The grounding arrangement of GIS will ensure

that touch and step voltages are limited to safe

values. Theenclosures of the GIS will be grounded

at several points such that there will be a grounded

cage around all live parts.

The inductive voltage against ground in each part

of the enclosure will not be more than 65 Volts.

Where operating mechanism cabinets are

mounted on the switchgear, the grounding will be

made by separate conductor. Bay control cabinets

will be grounded through a separate conductor.

All conduits and control cable sheaths will be

connected to the control cabinet grounding bus. All

steel structures will be grounded.

Each removable section of catwalk will be bolted

to the support structure for ground continuity.

The enclosure grounding system will be

designed to minimize circulating currents and to

ensure that the potential rise during an external or

internal fault is kept to an acceptable level.

. connectors will be of sufficient mechanical

strength to withstand electromagnetic forces as well

as capable of carrying the anticipated maximumfault current without overheating by at least from

two paths to ground from the main ground bus.

The guidelines of IEEE Std. 80-2000 on GIS

grounding, will be taken into consideration while

designing the grounding system for GIS

Grounding of GIS foundations

A simple monolithic concrete steel reinforced

slab is advantageous both as an auxiliary grounding

device and for seismic reasons. If a continuous

floor slab is used, a good adjunct measure is to tie

its reinforcing steel mesh to the common ground

bus (main ground bus) so that both the GIS

enclosures and the structural steel in and above the

foundation will be approximately the same

potential level

VI. Testing

Three types of testing has to be performed:

1.Type Tests:

1. Tests to verify the insulation level (Lightning

impulse, Switching impulse and ac withstand test

with PD) test on each GIS device (CB,

Disconnector, bus, etc):

2. Dielectric tests on auxiliary circuits.

3. Tests to prove the radio interference voltage

(RIV) level.

4. Tests to prove the temperature rise of any part of

the equipmentand measurement of the resistance of

the main circuit.


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5. Tests to prove the ability of the main and

earthing circuits to carrythe rated peak and the

rated short time withstand current.

6. Tests to verify the making and breaking capacity

of the includedswitching devices.

7. Tests to prove the satisfactory operation of the

included switchingdevices.

8. Tests to prove the strength of enclosures.

9. Verification of the degree of protection of the

enclosure.

10. Gas tightness tests

11.additional tests on auxiliary and control circuits.

12. Tests on partitions.

13. Tests to prove the satisfactory operation at limit

temperatures.

14. Tests to prove performance under thermal

cycling and gastightness tests on insulators.

15. Tests to assess the effects of arcing due to an

internal fault.

16. Seismic test

17. Test on Auxiliary switches (Electrical &

Mechanical Endurance,Heat run, IR & HVtest)

2.Routine / Acceptance Testing:

During manufacture and on completion, all

equipment will be subjected to the Routine tests as

laid down in IEC Standard IEC 62271-203.

Tests will include the following:

1.Dielectric test on the main circuit.

The dielectric routine test consists of a power

frequency voltage test on the main circuit including

PD measurement according The PD level needs to

be lower than 5 pC.

2.PD test:

No measurable partial discharge is allowed at 1.1

line-to-line voltage (approx. twice the phase-to-

ground voltage). This test ensures maximum safety

against insulator failure, good long-term

performance and thus a very high degree of

reliability.

3. Tests on auxiliary and control circuits.

4. Measurement of the resistance of the main

circuit.

5. Tightness test.

6. Design and visual checks.

7. Pressure tests of enclosures.

Each cast aluminium enclosure of the switchgear

shall be pressure-tested to at least double the

service pressure

8. Functional tests

9. Tests on auxiliary circuits, equipment and

interlocks in the controlmechanism.

10. Pressure test on partitions.

3.Tests after installation of complete GIS atSite:

After installation and before being put into service,

the GIS will betested in order to check the correct

operation and dielectric integrity ofthe equipment

as laid down in IEC 62271-203.

Tests will include the following:

1. Dielectric tests on the main circuits.

2. Dielectric tests on auxiliary circuits.

3. Measurement of the resistance of the main

circuit.

4. Gas tightness tests.

5. Checks and verifications.

6. Gas quality verifications.

7. On site power frequency voltage withstand test

with PD test.

8. Functional & interlock tests for all items

9. Demonstration of operational compatibility with

SCADA

10. Visual inspection, checks & verifications.

11. Mechanical operation tests of circuit breakers,

Disconnectors and earthingswitches and high-speed

earthing switches

12. Insulation resistance measurement

13. Tests on CTs and PTs

14. Tests on Surge Arresters


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VII. FAULTS AND PROTECTION

Faults Status of GIS:

1. mis-operation : grease hardening , corrosion of

switchgear, broken shaft

2.insulating materials : contact badness ofelectrodes, tran sient over voltage, tracking

phenomena of the polymeric insulation material.

3. damage of bushing : defect in voltage screen

4. breakdown of elbow connector : surface damage,

loose contact of connector

5. others : moisture absorption, trouble of control

circuits.

Protection :

Arc detection systems Arc detection systems are

protection systems that use sensors to detect thepresence of an internal arc and then isolate the

faulted section by opening of the incoming or

feeder circuit breaker. In general three types of

systems exist,

1. Light detection systems

2. Pressure rise detection systems

3. Micro switches situated on pressure relief

devices - A high speed fault diverter switch used in

response to arcing anywhere within the substation

to connect the gas-insulated high-voltage conductor

to ground for each phase of the system at highspeed to divert the fault current to ground

Protection of Power Transformer:

Table No.6

Incipient faults below oil level

resulting in decomposition of

oil

Buchholz relay

Sudden pressure relay

Pressure relief relay

Large internal faults (phase-to-

phase, phase-to-ground) below

oil level.Faults in tap-changer.

Buchholz relay

Percentage differentialprotection.

High speed high-set

overcurrent relay.

Saturation of magnetic circuit Over fluxing protectionOver voltage protection

Earth Faults Earth fault relay

Differential protection

Overload Thermal overload relay

Temperature relay sound

alarm

High voltage surges due tolightning, switching etc.

Surge arresterR-C Surge suppressors

Feederand Bus Coupler Protection:

Table No.7

Line Protection

Adapted

Type of relay

66 kV

Directional O/C &

E/FProtection

Numerical Relay

with IEC 61850Protocol

Local Breaker

Backup

Integrated in Dir.

O/C & E/FProtection

33/11 kV

Non-Directional

O/C & E/F

Protection

Integrated in Dir.

O/C & E/F

Protection

Local BreakerBackup

Integrated in Dir.O/C & E/F

Protection

VIII. LOAD SPECIFICATIONS

As GIS compactness allowed erecting the

substation in the vicinity of the load, the proposed

GIS can sustain the power demand of the fast

growing NOIDA region at industrial level. The

substation will have 20+20=40 MVA of installed

capacity. There will be in all four outgoing feeders,two with voltage rating of 33kV and two with

11kV.The substation mainly aim to supply the

industrial load with stipulated quality regulations.

We are also expecting general residential load. The

two 11 kV feeders will take care of the load in the

close region. For the load which are expected in

near future 33 kV feeders are provided that can fed

power to the another substation and then to

consumer. At present 47 large and small scale

industries are working with their full capacity. As

the growth of NOIDA in the recent past many more

industries are expected in this region, some of themare listed below.

Table No.8

Type Present Upcoming

Engineering 12 17

Material Science 2 4

Automobile 5 5

Paint 2 -

Automobile Parts 5 6

Consumer Electronics 9 11

Manufacturing 4 7

Software/IT services 8 20

Research andDevelopment

1 -

Industries mainly demand loads like inductionmotors, water pumps, small furnaces and other.

Beside the different industries nominal load of

residential area must be handled by the substation.

The substation will be designed to run 24 hour to

ensure continuous power supply to the industries

that are running in three shifts.


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IX. SPACE REQUIREMENT

The proposed 66/33/11 kV substation is of

INDOOR type and will be planned in a building.

The Fig shows the vertical section of the building

and placement of the various components. For

design purposes indoor temperaturesof 5 C to

+40 C and outdoor temperaturesof25 C to +40C shall be considered.The floor area of 20 ft x 8 ft complies with the ISO

668 standard for the switch gears.

The power transformer demands floor area of 30

ft. x 20 ft. Such two transformers will be installed

and hence the overall floor area required for

flooring is 40 ft. x 60 ft.

X. SYSTEM DATA AND CLIMATIC

CONDITIONS

Table No.9

Sr.No

.

Particulars

Value

1 General

I Installation

Indoor GIS

ii No. of

phases

3

iii

Standardsapplicabl

e

IEC and IS

2 Configuration

I Numberof Feeder

Bay

3 doublebay

Ii Numberoftransform

er Bay

2

Iii Number

of Bus

coupler

1

Iv GIS to

Transformer

Connectio

n

XLPE

powercables

V GIS to

Feeder

connection

XLPE

power

cables

Vi Number

of VT

3

Vii Numberof SA

2

Viii Future

extensionpossibility

One spare

FeederBay

Two spare

capacitorbanks

3 Service conditions

I Condensation Occasional

Ii Max Temp. in

Deg. C

50

Iii Min Temp. in

Deg. C

-5

Iv Daily average

Temp. in Deg. C

38

V Pollution Class III/25mm/

kVvi Average no of

rainy days/annum

50

7 Enclosure

I Material Aluminiu

m alloy

ii Painting shades

and thickness

Shade 631

(IS:5)

8 Auxiliary Supply

I For operation,

control and

signalling

220 Volts

(+10%&-

20%)

ii Other load 440/230


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Volts, AC

50 Hz

9 System Parameters

i Rated system

voltage

66/72.5 kV

ii One min. power

frequencywithstand voltage

140kv

(rms)

iii Rated frequency 50Hz

iv Rated continuousat 40 deg Cambient temp.

bus bar

2500A

v Feeder and

transformer bay

1600 A

vi Rated short

circuit withstand

current for 3seconds

25 kA

substation designing- gis

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