11kv & 3.3kv swgr

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Kochi Refinery PRESENTATION ON SHUT DOWN IN BPCL- KOCHI REFINERY RAHUL . R . NAIR Trainee-BPCL-KR

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Page 1: 11kV & 3.3kV SWGR

Kochi Refinery

PRESENTATION ON SHUT DOWN IN BPCL- KOCHI

REFINERY

RAHUL . R . NAIR Trainee-BPCL-KR

Page 2: 11kV & 3.3kV SWGR

Kochi Refinery

11 kV & 3.3 kV SWITCH GEAR

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Kochi Refinery

1. There are many substations present in the plant area and also the amount of

Switch Gears and other electrical distribution are in large numbers.

2. Let us consider a 11kV and 3.3kV present in DHDS substation and its

electrical distribution system.

3. The panels are HT-2007 ( 11kV SWGR ) and HT-2008 ( 3.3kV SWGR ).

4. The supply to the 11kV SWGR is fed from Captive Power Plant ( CPP ) through

transformer and supply to 3.3kV SWGR is fed from 11kV SWGR through a step down

transformer rated 11kV / 3.3kV.

5. The step-down transformers are present in the substation yard.

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Kochi Refinery

9. The 11kV and 3.3kV SWGR consists of two incomers ( 1 & 2 ) and a Bus Coupler .

10. The 11kV SWGR consists of transformer feeders and 3.3kV SWGR consists of HT

motor feeders.

11. These switch gears consists of mainly SF6 Circuit Breakers ( Sulphur Hexa-Fluride )

of 1250 A .

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Kochi Refinery

The panel consists of the following components :-

1. POWER SWITCHING DEVICES

a) SF6 Circuit Breakers

b) SFU ( Switch Fuse Unit ) with contactor module

c) High Rupturing Capacity Fuse ( HRC )

d) Contactors

2. CONTROL DEVICES

a) Trip Selection

b) TNC Switch

c) Ammeter Switch

d) Test Terminal Block

e) Synchronizing Selector Switch

PANEL DETAILS

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Kochi Refinery

3. INDICATIONS

a) Breaker On / Off

b) Auto Trip

c) Spring Charged

d) Ready to Close

e) Test / Service

f) Gas PR Low

4. METERING

a) Voltmeter

b) Ammeter

c) Watt Hour Meter

d) Power Factor Meter

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5. PROTECTION ( RELAYS )

a) Motor Protection

b) Sensitive Earth Fault

c) Over Current

d) Under Voltage

e) Check Synchronous

f) Master Trip

g) Inverse Definite Minimum Time O/C & E/F Protection

h) Line Potential Transformer

i) Bus Potential Transformer

6. AUXILIARY RELAYS

7. COMBIFLEX RELAYS

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Kochi Refinery

8. INTERLOCKS

a) Door Interlocks

b) Mechanical Interlocks

9. BUS DUCT / BUS CHAMBER

10. BREAKER SLIDING CONTACTS

a) Control Cables

b) Inter-panel Wiring

11. CABLES

a) Motor Cables ( 3-core )

b) Feeders ( 3.5-core )

c) XLPE

d) PVC

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Kochi Refinery

12. AUTO CHANGE-OVER SCHEME

13. CONTROL SUPPLY

14. SINGLE LINE DIAGRAM

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Kochi Refinery

POWER SWITCHING DEVICES

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SF6 CIRCUIT BREAKERS

SF6 circuit breakers may use compressed air (puff) or the magnetic force of the arc itself to

elongate the arc. As the length of the sustainable arc is dependent on the available voltage, the

elongated arc will eventually exhaust itself. Alternatively, the contacts are rapidly swung into a

small sealed chamber. The escaping of the displaced air thus blowing out the arc.

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Kochi Refinery

c)

The Isolator and Switch Fuse unit of Fuse Switch Unit are manually operated devices. A

Switch Fuse Unit or a Fuse Switch Unit also functions like the Switch, but can interrupt the

power supply by blowing the fuse in case the connected load draws excess current or when

a short circuit occurs.

SWITCH FUSE UNIT WITH CONTACTOR MODULE

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Kochi Refinery

CONTROL MODULE

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Kochi Refinery

a) In addition to providing a means to open and close the contacts manually, a

circuit breaker must automatically open its contacts when an overcurrent is sensed.

The trip unit is the part of the circuit breaker that determines when the contacts will

open automatically. The trip unit includes a trip mechanism that is held in place

by the trip bar. As long as the trip bar holds the trip mechanism, the mechanism

remains firmly locked in place. Trip flags off when a fault occurs ( over load ,short

circuit , under voltage etc).

TRIP

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Kochi Refinery

b)

TNC Switch is a three position Switch. The switch are of two types : i) Having lockable Trip

position and other with ii) spring return to normal Neutral position. For manual operation this

switch is used to TRIP a breaker by moving it towards trip position and close by moving

it towards Close position.

In neutral position all the operations on AUTO mode or from remote can be done, as per the

scheme.

For keeping the breaker in OFF condition or for isolation, the switch can be kept in lockable

TRIP position, if that facility is available in the switch. 

TNC SWITCH

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INDICATIONS

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Kochi Refinery

a)

GREEN : Breaker Open & Mechanism charged

RED : Breaker Closed

AMBER : Trip/Trip Circuit Trouble

WHITE : Trip Circuit Healthy

ON / OFF INDICATIONS

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Kochi Refinery

b) During auto trip the circuit breaker will not get ON without re-setting the fault or

any other cause for the trip. Once the trip is reset , the circuit breaker can be put on

to feed the load.

c) Spring is charged by providing a DC-voltage for the spring charging motor .The

control circuit requires DC voltage. This will charge the breakers within minutes .

Thus the charged spring stores potential energy which is used to operate quick

mechanisms( opening or closing of breaker contacts ).

AUTO TRIP & SPRING CHARGING

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Kochi Refinery

d) This SPDT switch indicates that the circuit breaker is ready to close and

that the following conditions exist:

The circuit breaker is open

The stored energy mechanism is charged

The control unit is reset

The circuit breaker opening push button is neither locked nor

padlocked

The circuit breaker is in the fully connected or test position

The switch is field-installable.

READY TO CLOSE

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e) When the breaker is racked out completely for maintenance a test indication is

signalled on PMCC. At this point of time the breaker does not have any contact

with the bus bars.

When the breaker is racked in completely a service indication is signalled on

PMCC . This shows that the breaker is in service and ready to use.

TEST / SERVICE

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GAS PRESSURE LOW

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METERING

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Kochi Refinery

a) A voltmeter is an instrument used for measuring electrical potential difference between two

points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to

the voltage of the circuit. Digital voltmeters give a numerical display of voltage by use of an

analog to digital converter.

VOLTMETER

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Kochi Refinery

b) An ammeter is a measuring instrument used to measure the electric current in

a circuit. Electric currents are measured in amperes (A), hence the name. Instruments

used to measure smaller currents, in milli ampere or micro ampere range, are

designated as milli-ammeters or micro-ammeters. 

AMMETER

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Kochi Refinery

c) Watt hour meter is a device that measures and records over time the electric

power flowing through a circuit. Although there are several different types of watt- hour meters,

each consists essentially of a small electric motor and a counter. A precise fraction of the

current flowing in the circuit is diverted to operate the motor. The speed at which the motor

turns is proportional to the current in the circuit, and, therefore, each revolution of the

motor’s rotor corresponds to a given amount of current flowing through the circuit.

WATT-HOUR METER

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POWER FACTOR METER

A power factor meter is a kind of electrodynamometer, which is constructed with two

coils that are movable. These coils are set at 90 degrees to one another. One can

measure the power factor with the help of a power factor meter. The application of a

power factor meter is numerous like start up analysis of a motor or even detection of

hot spots.

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PROTECTION

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a) Motor Protection Relays are useful for protection of 3-phase AC induction

motors against various hazards. With their unique advantages they eliminate use of a

thermal / bimetal relay for motor protection. Being current sensing, they are to be selected

according to motor rating and are available for practically all ranges of motors. These relays

are ideally suitable for Air-conditioning Compressor motor protection, as also for motors in

machines, conveyors, cranes/hoists and lifts, and for pumps.

MOTOR PROTECTION RELAYS

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b) Sensitive Earth Fault Relay is a type of relay that is used to detect the presence

of an earth fault during the operation of an electrical device. Earth Fault occurs when

there is unbalancing of loads due to which the amount of current flowing through the

three phases ( R,Y,B ) will be in a different ratio.

SENSITIVE EARTH FAULT RELAY

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c) An Over Current Relay is a type of protective relay which operates when the

load current exceeds a preset value. The ANSI device number is 50 for an

instantaneous over current (IOC), 51 for a time over current (TOC). In a typical

application the overcurrent relay is connected to a current transformer and

calibrated to operate at or above a specific current level. When the relay

operates, one or more contacts will operate and energize to trip (open) a circuit

breaker

OVER CURRENT RELAY

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Kochi Refinery

d) A relay that has contacts that operate when the voltage drops below a set

voltage is called Under Voltage Relays. Under voltage relays are used for protection

against voltage drops, to detect short-circuit faults, etc.

An undervoltage release triggers the breaker to open when the applied voltage falls

below a threshold. Often, an undervoltage release is operated from the system and

is intended to cause the breaker to open in the event something happens to cause

the system voltage to collapse.

UNDER VOLTAGE RELAYS

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e) Check Synchronising Relay : When closing a circuit breaker between two

energized parts of the power system, it is crucial to match voltages on both sides of the

circuit breaker before closing. If this matching or "synchronizing" process is not done

correctly, a power system disturbance will result and equipment can be damaged.

In order to synchronize properly, three different aspects of the voltage across the circuit

breaker must be closely monitored. The three aspects of the voltage are called the

synchronizing variables and are:

1. The voltage magnitudes

2. The frequency of the voltages

3. The phase angle difference between the voltages

CHECK SYNCHRONISING RELAY

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Kochi Refinery

MASTER TRIP RELAY

Master Trip relays or Lockout relays are bipolar devices designed to operate when

voltage is applied. They are a link between protective relays and power circuit

controlling devices such as circuit breakers. Their purpose is to multiply the outputs of

protective relays or control relays so that one relay can trip and block closing of numerous

power circuit controlling devices.

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Kochi Refinery

IDMTL O/C & E/F PROTECTION

IDMTL O/C & E/F PROTECTION is design to meet demand of low and medium

switchgear control. This type of relay is a 3 OC and 1 EF relay with Instantaneous high set

and programmable output to simplify feeder protection wiring. It continuously monitors all 3

phase and earth current, through CT connections. The high-speed micro-controller samples

this current through a 12-bit A/D converter. The micro- controller performs powerful Digital

Algorithms to find out Amplitude of current signal, and then this value is use for protection and

metering function. All measurement is tuned to fundamental frequency. Each input current is

also displayed on 16 x 2 LCD

display for metering. The Relay is having main three functions 1) Protection 2) Self-

Supervision 3) Measurement

Page 35: 11kV & 3.3kV SWGR

Kochi Refinery

LINE POTENTIAL TRANSFORMER

Potential Transformer is designed for monitoring single-phase and three-phase

power line voltages in power metering applications. A Potential Transformer is a special

type of transformer that allows meters to take readings from electrical service connections

with higher voltage (potential) than the meter is normally capable of handling without at

potential transformer. Potential transformer models are available for metering AC

voltages from 120 volts AC to 36,500 Volts AC with burden ratings up to 500 VA.

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Kochi Refinery

BUS POTENTIAL TRANSFORMER

It's a PT (potential transformer) that's attached to the bus. This depends

on the burden rating of the PT. If it's a 15VA PT, made for a secondary voltage of

120V, then the maximum secondary current should not exceed 0.125A.

Potential transformer is that which transforms one range of voltage (potential

difference ) to another range without changing frequency. Potential transformers are used to

(1) reduce the value of a high-voltage supply to a lower value (often 120 V) so that it may

be read by ordinary voltmeters, and (2) to electrically-isolate the voltmeter from the high-

voltage source for the purpose of safety.

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Kochi Refinery

AUXILIARY RELAY

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Auxiliary Relay is relay which will repeat the operations of protective relays such

as tripping , time lag , breaking of trip circuit current , giving alarms , showing flags

etc. Protective relays contacts are light in weight and hence cannot carry large

amount of current for a long period. Therefore auxiliary relays, auxiliary switches and

repeat contacts are used to assist protective relays.

AUXILIARY RELAY

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BUS DUCT / BUS CHAMBER

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A bus duct is metal raceway that supports and contains a group of electrical

bus bars. The duct comes in standard 10 foot lengths. 

One of the greatest advantages of bus ducts is that they are capable of

adding or removing a branch circuit without removing voltage from the whole duct.

BUS DUCT / BUS CHAMBER

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Kochi Refinery

INTERLOCKING

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a) This lock prevents the compartment door from being opened when the circuit

breaker is in the connected position. If the circuit breaker is put into the "connected"

position with the door open, the door can be closed without disconnecting the circuit

breaker. The figure typically shows a door interlock pattern.

DOOR INTERLOCK

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Kochi Refinery

b) mechanical interlocks

■ disconnecting when circuit breaker is closed

During any disconnecting attempt when the circuit breaker is closed, an interlocking

device ensures the tripping of the circuit breaker before the actual separation of the

main disconnects. The circuit breaker remains, however, operable in the other

positions: test, disconnected and withdrawn.

MECHANICAL INTERLOCKS

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Kochi Refinery

■ circuit breaker closing when not completely connected

The interlocking device mentioned above prevents closing of the circuit breaker if the

connecting operation is not completely achieved.

■ connecting circuit breaker when door opened

VPEC and VPOC options prevent the compartment door from being opened when

the circuit breaker is in the connected position and from connecting the circuit

breaker when the door is open.

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Kochi Refinery

BREAKER SLIDING CONTACTS

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a) Control Cables are a multistrand cable for transmission of information

on the state, location, or operating conditions of objects being controlled. It is used where

direct access to such objects is difficult or impossible. Control cables occupy an

intermediate position between power cables and communications cables. They are widely

used to connect electric instruments and apparatus, for secondary switching of remote-

control starters and regulators, for protective relaying, and in automation.

CONTROL CABLES

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Kochi Refinery

b) Inter Panel Wiring is used for control equipment in control panel manufacture,

public buildings, control equipment, process control and automation, defence and

power network distribution.

INTER PANEL WIRING

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Kochi Refinery

CABLES

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Kochi Refinery

a) 3 Core Cables are manufactured for critical space requirement, protection

against rain-water and against ingress of small solid foreign bodies.

These Cables are produced from best quality electrolytic copper, which is

drawn, annealed on-life and bunched on automatic machines to ensure

flexibility and uniform resistance. The conductors are insulated with a

special grade of PVC on sophisticated co-extrusion lines.

MOTOR : 3 – CORE CABLES

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b) 3.5 core cables are generally used for lighting applications & in the applications

where the 0.5 core is used for neutral conductor because neutral conductor has

almost no - load to carry, thus saving the cost, by using half conductor size.

Neutral conductor is having half size in 3.5 core cable because neutral doesn't

have to carry the load current .This is either used for unbalanced current (in Y-

connection) or for earthing purpose which don't require high ampere rating.

FEEDER : 3.5 – CORE CABLES

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XLPE CABLES

Cross-linked polyethylene, commonly abbreviated PEX or XLPE, is a form

of polyethylene with cross-links. It is formed into tubing, and is used

predominantly in building services pipework systems, radiant heating and cooling

systems, domestic water piping, and insulation for high tension (high voltage)

electrical cables. XLPE-insulated cables have a rated maximum conductor

temperature of 90 °C and an emergency rating up to 140 °C, depending on the

standard used. They have a conductor short-circuit rating of 250 °C. XLPE has

excellent dielectric properties, making it useful for medium voltage—10 to 50 kV AC,

and high voltage cables—up to 380 kV AC- voltage.

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Kochi Refinery

PVC CABLES

PVC is commonly used as the insulation on electrical cables; PVC used for this

purpose needs to be plasticized.

In a fire, PVC-coated wires can form hydrogen chloride fumes; the chlorine serves

to scavenge free radicals and is the source of the material's fire retardance. While

HCl fumes can also pose a health hazard in their own right, HCl dissolves in

moisture and breaks down onto surfaces, particularly in areas where the air is cool

enough to breathe, and is not available for inhalation. Frequently in applications where

smoke is a major hazard (notably in tunnels and communal areas) PVC-free cable

insulation is preferred, such as low smoke zero halogen (LSZH) insulation.

Page 53: 11kV & 3.3kV SWGR

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AUTO CHANGE-OVER SCHEME

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Kochi Refinery

AUTO CHANGEOVER SCHEME

Page 55: 11kV & 3.3kV SWGR

Kochi Refinery

FLOW CHART

Page 56: 11kV & 3.3kV SWGR

Kochi Refinery

CONTROL SUPPLY

Page 57: 11kV & 3.3kV SWGR

Kochi Refinery

Control Supply to PMCC is 110 V dc and is fed from DCDB ( Direct Current

Distribution Board)

The DCDB is fed from battery charger in the substation.

The battery charger has a battery bank as back-up in case of supply failure to

the charger.

CONTROL SUPPLY

Page 58: 11kV & 3.3kV SWGR

Kochi Refinery

SINGLE LINE DIAGRAM

11kV SWGR

3.3 kV SWGR

PMCC

MCC

11kV / 3.3kV 11kV / 3.3kV

Incomer-1Bus Coupler

Incomer-2

11kV / 0.433kV11kV / 0.433kV

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Kochi Refinery

THANK YOU