Pgcil Project Report

NTRODUCTION

400 KV Sub-Station: BALLABGARH is a vital node for disbursement of power to

Northern States of India. It is located at a distance of 47 KM from DELHI near Samaypur

village of BALLABGARH (Distt. FARIDABAD) of Haryana State. Normally it imports

power from generating stations of SINGRAULI/RIHAND, AURAIYA, DADRI reroute

the substations of KANPUR, AGRA, DADRI & MAINPURI respectively and the same

is exported to RAJASTHAN, HARYANA/DELHI via BHIWADI S/S, BAMNAULI S/S

& 220 KV BBMB SAMAYPUR. Further BALLABGARH being one of the five nodes of

400 KV RING MAIN double circuit line around national capital of DELHI, assumes the

additional onus of responsibility for ensuring uninterrupted power supply to the

CAPITAL. The prestigious & very first Remote Operation of S/S i.e. Remote operation

of BHIWADI S/S is being controlled from BALLABGARH control room and further

more, India’s first indigenous FACTS has been test charged at Ballabgarh on 400 KV

S/C Ballabgarh-Kanpur line. However Fixed Series Compensation (35%) on 400 KV

BLB-KNP line executed by M/S BHEL is in service since July’2002. This Fixed Series

Compensation was first project on any 400 KV line in India.

FEATURES OF BALLABGARH S/S

TOTAL AREA 135 Acres

BUSBAR SCHEME ONE & HALF CB

NO. OF BAYS COMMISSIONED 28

No. of TRANSMISSION LINES 09

No. of ICTs (315 MVA) 04

No. of BUS REACTOR (80 MVAR) 01

COMMISSIONING CHRONOLOGY

• 400 KV BLB-JPR S/C (NOW BHIWADI) 13 September 1988

• 400 KV 315 MVA ICT-I 26 September 1988

• 400 KV BLB-KNP S/C 13 October 1988

• 400 KV 315 MVA ICT-I I 26 September 1988

• 400 KV 80 MVAR BUS REACTOR 23 June 1989

• 400 KV BLB-DDR D/C 25 June 1990

• 400 KV 315 MVA ICT –III 22 January 1991

• 400 KV BLB-AGR S/C 26 December 1991

• 400 KV 315 MVA ICT –IV 30 June 2002

• 400 KV BLB – MAINPURI –I 11 May 2005

• 400 KV BLB –MAINPURI-II 08 May 2005

• 400 KV BLB-BAMNAULI-I 18 Aug 2004

• 400 KV BLB-BAMNAULI-II 21 Aug 2003

• FACTS STAGE-I 01 July 2002

• FACTS STAGE-II TEST CHARGE 29 November 2004

• REMOTE OPERATION OF BWD S/S 01 December 2003

LINE LENGTH (KM)

• 400 KV BLB-KNP S/C 393

• 400 KV BLB-BHD S/C 60

• 400 KV BLB-AGR S/C 181

• 400 KV BLB-DDR 54

• 400 KV BLB-Greater Noida 39

• 400 KV BLB-BAM D/C 53

• 400 KV BLB-MNP D/C 236

Following are the Key Equipments of the Substation:

1. TRANSFORMERS & REACTORS

2. CIRCUIT BREAKERS

3. CURRENT TRANSFORMER

4. ISOLATORS

5. CAPACITVE VOLTAGE TRANSFORMER

6. WAVE TRAP

7. LIGHTENING ARRESTERS

8. FACTS

BESIDES THERE ARE OTHER AUXILLIARY SYSTEMS FOR SMOOTH

OPERATION OF THE SUBSTATION:

1. PLCC

2. FIRE FIGHTING SYSTEM

3. ACDB (AC DISTRIBUTION BOARD)

4. DCDB (DC DISTRIBUTION BOARD)

5. DG SET

6. BATTERY BANK

THE RELAYS SCHEMES PROVODEED FOR PROTECTION PURPOSES ARE AS

UNDER:

FOR LINE & BUS BAR

1. DISTANCE PROTECTION FOR LINE

2. OVER VOLTAGE PROTECTION

3. AUTO RECLOSE SCHEME

4. BUS BAR PROTECTION

5. LOCAL BREAKER BACK UP

6. POLE DESCREPENCY

FOR TRANSFORMERS AND REACTORS

1. DIFFERENTIAL PROTECTION

2. REF PROTECTION

3. BACK UP O/C AND EARTH FAULT PROTECTION

4. CORE PROTECTION

5. OTI/WTI

6. PRD

OPERATION DETAIL

GENERAL

In general if everything is normal then the shift staff has to fill the operation

records as listed in enclosure.

All readings must be taken at proper time as per OS norms.

There should not be any over writing or cutting on Log Books.

Readings of switch yard equipments, A/C plant, DG set, F/F system, Auxiliary

system must be taken locally.

Normally there should not be any alarm on control panel windows in C/R, A /C plant

control panel, DG control panel and F/F system Control panel. In case any alarm appears

then try to reset the same and inform to maintenance In-charge.

OPERATIONAL STRATEGY IN CASE LINE AUTO RECLOSES.

• About 90% of the faults on line are transient in nature because line passes through

forests, other areas also. In this case fault is not of permanent nature, so an

attempt is to be taken to reclose the line.

• As soon as there is any fault in the line, Main-I and Main-II protections will

operate and particular pole of CB’s (main & tie) will open at both ends. After

dead time (1 second), which starts since the operation of Main-I and Main-II, A/R

attempt is taken by A/R relay and if fault is cleared with-in dead time, CB at both

ends will close but If fault is persisting 3 phase tripping will takes place. If fault is

again repeated with in reclaim time after successful A/R of line, which is 25

seconds for A/R relay, then also 3 phase tripping takes place. After 25 seconds of

auto - reclosing A/R relay become normal for next operation.

ACTION TO BE TAKEN BY SHIFT STAFF:

• Acknowledge the alarm by pressing Acknowledge push button on respective

panel.

• Record the time and consult other end also, see time in DR, EL prints.

• Normally CB auto trip and I/T (inter trip) signal receive facia will appear on

control panel along with Main I / II Prot. Operated.

• Note down the flags on protection relay panels as below.

i) Main-I ii) Main-II iii) Trip Relay.

iv) Any other relay v) Fault locator readings.

vi) Increment in PLCC counter.

• Inform S/S In-charge immediately and discuss before passing the flags to CPCC.

• Inform verbally and by written message to CPCC about above with flags & facias

details.

• Reset the flags if there is no confusion as per advise of S/S In-charge.

• Take DR print out.

• Take E/L print and cross check timings.

• Take other end flags.

• Inform the line staff about the fault and fault locator readings of both ends.

OPERATIONAL STRATEGY IN CASE LINE TRIPS OR A/R

UNSUCESSFUL:-

The reason for unsuccessful auto-reclosure at one end or at both ends will be

following:-

• Fault is of permanent in nature, may be due to snap of Phase wire or earth wire.

• 1 phase fault converted into 3 phase faults.

• CB operating mechanism oil/SF6 PRESSURE is low, it will block auto reclose.

• Wrong detection of fault by relay.

• PLCC channel is not healthy.

• Fault is repeated on other healthy phase with in dead time on the same phase.

• A/R relay DC is not healthy.

• Direct trip received from other end.

• A/R success full at one end and failed at other end, then line may trip on Over

voltage from other end.

• In case of ALSTOM system, 186A & B will appear on auto recluse relay if auto

reclose fails and in ABB auto reclose lock out relay.

• In case of tripping of line, repeat Sl. No. 1 to 5 as above in 1.1 ( line auto

recloses) but ask for the charging code from CPCC after inspecting the switch

yard equipments and consulting other end.

• If line is open at one end only, synchronize after taking permission from CPCC.

• If the line is open at other end only, permit him to close if CPCC code is there and

no problem at other end.

• If Line trips at both ends take permission from CPCC to charge from one end and

synchronize at other end.

.

OPERATIONAL STRATEGY IN CASE LINE TRIPS.

Due to other faults (O/V, D/T RECEIVE ETC.)

The reasons other than earth fault for tripping of line are given below.

1) Over voltage protection operates [voltage goes > (440-460) KV for 5

Seconds or 600 KV for instantaneous tripping).

2) Shunt reactor protection operates.

3) Direct trip signal received (85 LO in ALSTOM system).

In case of above there will not be any flag on Main-1 / Main-2 panel & fault

locator will not give any reading. Follow steps 1 to 5 as in the section “Line

auto recloses successfully”.

i) In case of over voltage take permission from CPCC if voltage has come

down. Consult other end and Charge/Synchronize the line.

In case over voltage stage-2 operates then inform S/S In-charge for further

restoration of the feeder.

ii) Bus reactor has hand reset type of trip relay, so when ever Bus reactor

trips, clearance is to be taken from S/S In-charge and then reset the relay

by pressing push button.

iii) In case direct trip signal receives, consult other end if they find out the

reason for tripping after that code may be taken for charging and

synchronization of line.

OPERATIONAL STRATEGY IN CASE BUS BAR PROTECTION AND LOCAL

BREAKER BACK UP (LBB) PROTECTION OR BREAKER FAILURE RELAY

(BFR) OPERATES.

The operation of Bus Bar protection is very rare. It can operate in case some

earthing is left during the shut down or bus post insulator has failed.

Bus bar is having differential protection. It is divided into Zone-I covering B/B– 1

and Zone -2 covering B/B- 2 and check zone covers both buses. Core-I of all CTs

which are used in Bus Bar protection is connected with Check zone and core-2 connected

to zone-1 or zone-2 as per Bay connection to Bus-1 or Bus-2. CT cores 1&2 used for bus

bar protection has 2000/1 ratio. For any tripping check zone & zone-1 or zone-2 has to

pick up. This is for giving more security in tripping. The relay setting is 100V and relays

are located in BB panel.

LBB (local breaker back up) or BFR will operate when main protection

has operated and tripping has been extended to trip relay and CB fails to trip due

to mechanical problem etc. It is delayed protection if the current to the LBB or

BFR persists for 200 ms then only relay will operate. Setting of ABB relay

RAICA) is 200mA and that of ALSTOM relay CTIG 1.2 amps for phase element

& 0.4 amp for neutral element with 1000/1 A CT. The tripping relays for both

these protection are common and are located in bus bar Panel. In case of operation

of these protection either B/B-I or B/B-II connected all CB’s will trip and B/B

will become dead.

STEPS TO BE TAKEN

• Acknowledge the alarm on control panel.

• In case of B/B tripping note down the flags on B/B panel.

• In case of LBB or BFR note down the flags on respective panels.

• Inform S/S In-charge and CPCC immediately.

• Do not charge the Bus or line till clearance is given by S/S In-charge and CPCC.

• After inspection and clearance is accorded by S/S In-charge and ask for code from CPCC.

• Reset the B/B trip relays by pressing the push button in B/B panel.

• Without resetting the B/B trip relays, CB’s cannot be closed because closing command for CB goes through the contact of this relay.

• If code is given by CPCC charge the B/B by closing CB’s and record time and other parameters

SHUTDOWN PROCEDURES

SEQUENCE OF MANDATORY OPERATIONS FOR SHUTDOWN OF LINE:

A Avail permission code from CPCC for shut down of the line. Pass on the

same code to remote end.

B Note down the system parameters of all lines/ICTS.

C Open the Main CB of the line.

D Open the Tie CB of the line.

( If the remote end opens the line from their end, Main CB & Tie CB will

open automatically)

E Put the Auto Reclose switch (A/R) of the line in “NON AUTO” position.

F Open the line Isolator *89L.

G Open the Main Bay Isolator *89A & Tie Bay Isolator *89A & *89B.

H Open Bus side Isolator *89 & Reactor isolator *89R.

I Check physically for proper opening of all Isolators done in F, G, H.

J Ensure that line Isolator at the other end is open.

K Get permission from other end to earth the line.

L Close the earth switch of the line Isolator *89LE and inform other end.

M Ensure that the line is earthed at the other end.

N Attach “DO NOT OPERATE” board at the control panel of the line bay.

O Issue PTW (Permit To Work) on the line and individual equipment.

SEQUENCE OF MANDATORY OPERATIONS FOR SHUTDOWN OF

ICT:

A Avail permission code from CPCC for shut down of the ICT. Pass on the

same code to BBMB.

B Note down the system parameters of all lines/ICTS.

C Open the 400 KV Main CB of the ICT.

D Open the 400 KV Tie CB of the ICT.

E Open the 220 KV CB of the ICT.

F Open the 400 KV line Isolator *89L of the ICT.

G Open the Main Bay Isolator *89A & Tie Bay Isolator *89A & *89B.

H Open Bus side Isolator *89 & 220 KV side isolator L*89.

I Check physically for proper opening of all Isolators done in F, G, H.

J Ensure that line Isolator at BBMB end is open.

K Get permission from BBMB to earth the ICT.

L Close the earth switch of the ICT from 220 KV side Isolator L*89E.

M Close the earth switch of the ICT from 400 KV side Isolator *89LE.

N Attach “DO NOT OPERATE” board at the control panel of the 400 KV

& 220 KV ICT bay.

O Issue PTW (Permit To Work) on the ICT and individual equipment.

SEQUENCE OF MANDATORY OPERATIONS FOR THE S/D OF BUS 1/ BUS 2:

A. Avail permission code from CPCC for shut down of the BUS 1/ BUS 2.

B. Open all the CB’S connected to BUS-I/ BUS 2.

C. Put the Auto Reclose switches (A/R) of all the above CB’s in “NON AUTO”

position.

D. Open all the Isolators of the bays connected to BUS 1/ BUS 2.

E. Check physically for proper opening of all Isolators done in D.

F. Ensure that the BUS-I/ BUS-2 voltage is around 10KV (due to induction).

G. Close Bus-I/ Bus-2 earth switch 1389E / 1589E Bus side respectively.

H. Ensure that the Bus selection switch of voltage / frequency is on Bus-II/ Bus-I

respectively.

I. Ensure that the bus selection latch relay is correctly operated and MW, MVAR

and Current of all feeders are matching.

J. Ensure that all the energy meters of feeders & ICTs are running

K. Issue the PTW (PERMIT TO WORK) on individual equipment.

CHARGING & SYNCHRONISING PROCEDURES

SEQUENCE OF OPERATION FOR CHARGING & SYN. OF LINE

GENERAL OPERATING INSTRUCTIONS

A. Ensure all permits issued are returned and cancelled. (i.e. Line,

Switchyard, CP/RP Maintenance)

B. Check for removal of all men and material from S/Y physically.

C. Physically check for removal of earthing done at working site, both

permanent and temporary.

D. Ensure that all S/Y equipments of the line on which PTW’S were cleared,

are in operating condition.

E. Check for SF6/ OIL pressure of Main & Tie CB.

F. Ensure local/remote switch of CB’s are in “Remote” position.

G. Ensure that all relay flags are reset.

H. Check for no annunciation pending on window and do lamp test OK.

I. Ensure that D/R,E/L, F/L are in service.

J. During charging of the line from BALLABGARH end the A/R selection

switch of both Breaker must be kept in NON AUTO mode to avoid auto

re-closure of switch on to fault. After successful synchronizing same may

be kept in 1 PH mode.

SEQUENCE OF OPERATION FOR LINE CHARGING:

A. Confirm the removal of line earthing at other end.

B. Close all the isolators i.e. Reactor isolator, Main Bay & Tie Bay isolators.

C. Close the line isolator.

D. Check physically the closing of all isolators done in B,C .

E. Give clearance to close line isolator at remote end and confirm.

F. Note down the counter reading of all PLCC channels.

G. Note down the parameters of all lines and Auto Transformers.

H. Take permission from CPCC for charging the line and inform other end.

I. For the charging and synchronising of the line, charge the line from the

end where voltage is less.

J. If voltage is less at our end then charge the line and confirm synchronising

of the line from other end.

K. If line trips during charging on SOTF then no second attempt is to be

made for charging the line and inform to S/S In-charge and CPCC.

L. If voltage is less at other end then line is to be charged from other end and

after confirming the voltage in all the three phases line synchronised from

our end through synchronising trolley. In no case check synchronising

relay should be bypassed.

M. After synchronising the line note down the readings and check the current

in all the three phases and inform to CPCC.

N. Check all the relay & control panels and note down the PLCC readings. If

any abnormalities observed then inform to S/S in-charge.

SEQUENCE OF OPERATION FOR CHARGING & SYNCHRONISING 315

MVA 400/220/33KV ICT.


A. Ensure all permits issued are returned and cancelled. (i.e. ICT,

Switchyard, CP/RP Maintenance)




D. Ensure that all S/Y equipments of the ICT & Bay on which PTW’S were

cleared, are in operating condition.

E. Check for SF6/ OIL pressure of Main & Tie CB.



H. Check for no annunciation pending on window and do lamp test OK.

I. Ensure that Event Logger is in service.

PRE-CONDITIONS FOR CHARGING ICT’S.

• ICT shall be charged preferably from 220 KV side and synchronized from 400

KV side in normal condition.

• In case of Auto transformer has undergone major overhaul or oil has been

exposed to the atmosphere, values of BDV, PPM shall be taken before

charging the transformer.

SEQUENCE OF OPERATIONS

A. Confirm the removal of earthing at BBMB end, if any, and give clearance

for closing the 220 KV line isolators at their end.

B. Close 220 KV side Autotransformer isolator L*489.

C. Close all the 400 KV side isolators of Main & Tie Bay.

D. Check physically the closing of all isolators done B & C.

E. Inform the readiness to CPCC.

F. Take permission from CPCC for charging the ICT-I from 220 KV side.

G. Note down all parameters of ICT’s and lines.

H. Check physically the healthy ness of transformer.

I. Close 220 KV Breaker of ICT. As such the Auto- transformer is charged

from 220 KV side.

J. In case the Auto transformer trips on fault, second attempt MUST NOT be

made until ICT is properly tested and reason for tripping is ascertained.

K. Close 400KV Main and Tie CB’s of ICT as per requirement. In no case

check synchronizing relay should be bypassed.

L. After synchronizing the ICT note down the readings and check the current

in all the three phases and inform to CPCC.

M. Check all relay and control panels and equipments in the switch yard for

any abnormalities and inform S/S In-charge.

SEQUENCE OF OPERATION FOR CHARGING BUS-1/ BUS-2


A. Ensure all permits issued are returned and cancelled. (i.e. Bus-1/ Bus-2,

Switchyard, CP/RP Maintenance).




D. Ensure that all S/Y equipments on which PTW’S were cleared, are in

operating condition.

E. Check for SF6/ OIL pressure of all the CBs.



H. Ensure that Event Logger is in service.

3.2 SEQUENCE OF OPERATION:

A. Close all the isolators of the bays connected to Bus-1/ Bus-2.

B. Check physically the closing of all isolators.

C. Take permission from CPCC for charging the Bus-1/ Bus-2.

D. Close all the CBs of the bays connected to Bus-1/ Bus-2.

E. Check all the equipments in switchyard. If any abnormalities observed

then inform to S/S in-charge.

Switchgears :

The apparatus used for switching, controlling and protecting the electrical circuits and

equipment as switchgear.

Essential features of switchgear :

A. Complete reliability.

B. Absolutely certain discrimination

C. Quick operation

D. Provision for manual control

E. Provision for instruments

Switchgear Equipment :

Switchgear covers a wide range of equipment concerned with switching and interrupt

currents under both normal and abnormal conditions. It includes switches, fuses, circuit

breakers, relays and other equipment. A brief account of these devices is given below.

A. Switches : A switch is a device which is used to open or close an electrical circuit

in a convenient way. It can be used under full-load or no-load conditions but it

cannot interrupt the fault contacts. This is particularly true for circuits of high

voltage and large current capacity. The switches may be classified into air

switches and oil switches. The contacts of the former are opened in air and that of

the latter are opened in oil.

i. Air-break switch : It is an air switch and is designed to

open a circuit under load. In order to quench the arc that

occurs on opening such a switch, special arcing horns

are provided. Arcing horns are pieces of metals

between which arc is formed during opening operation.

As the switch opens, these horns are spread farther and

farther apart. Consequently, the arc is lengthened,

cooled and interrupted. Air-break switches are

generally used outdoor for circuits of medium capacity

such as lines supplying and industrial load from a main

transmission line or feeder.

ii. Isolator or disconnecting switch: It is essentially a knife

switch and is designed to open a circuit under no load.

Its main purpose is to isolate one portion of the circuit

from the other and is not intended to be opened while

current is flowing in the line. Such switches are

generally used on both sides of circuit breakers in order

that repairs and replacement of circuit breakers can be

made without any danger. They should never be opened

until the circuit breaker in the same circuit has been

opened and should always be closed before the circuit

breaker is closed.

iii. Oil breaker: The content of such switches are opened

under oil usually transformer oil. The effect of the oil is

to cool and quench the arc that tends to form when the

circuit is open. These switches are used for circuit of

high voltages and large current carrying capacity.

B. Fuses : A fuse is a small piece of wire of thin strip which melt when excessive

current flow through it for sufficient time. It is inserted in the circuit in the series

to be protected. Under normal operating condition the fuse element it at a

temperature below its melting point. Therefore it carry normal load current

without overheating. However, when a short-circuit or overload occur, the current

to the fuse element increases beyond its rated capacity. This raises the

temperature and the fuse element is melt, disconnecting the circuit protected by it.

C. Circuit Breaker: Circuit Breaker is an instrument which can open or close a circuit

under all conditions viz no load, full load, or fault condition. It is so designed that

it can be operated manually under normal condition or automatically in faulty

condition. For the latter operation, a relay circuit is used with the circuit breaker.

The circuit breaker essentially consists of moving and fixed contacts enclosed in

strong metal tank and immersed in oil, known as transformer oil.

Under normal operating conditions, the contacts remains closed and the circuit

breaker carries the full-load current consciously. In this condition, the emf in the

secondary winding of current transformer(C.T.) is sufficient to operate the trip

coil of the breaker but the contacts can be opened by manual or remote control.

When a fault occurs, the resulting over current in the C.T. primary winding

increases the secondary emf. This energies the trip coil of the breaker and moving

contacts are pulled down, thus opening the contacts and hence the circuit. The arc

produced during the opening is quenched by the oil. It is interesting to note that

relay performs the function of detecting a fault whereas the circuit breaker does

the actual circuit interruption.

D. Relay: A relay is a device which detects the fault and supplies information to the

breaker for circuit interruption. It is divided into three parts viz.

i. The primary winding of a current transformer which in

series with the circuit to be protected. The primary

winding often consists of the main conductor itself.

ii. The second circuit is the secondary winding of C.T.

connected to the relay operating coil.

iii. The third circuit is the tripping circuit which consists of

source of supply, trip coil of circuit breaker and the

relay stationary contacts.

Under normal load conditions, the emf of the secondary winding of C.T. is small

and the current flowing in the relay operating coil is insufficient to close the relay

contacts. This keeps the trips coil of the circuit breaker unenergised. Consequently, the

contacts of the circuit breaker remain closed and it carries the normal load. When a fault

occurs, a large current flows through the primary of C.T. This increases the secondary

emf and hence the current through the relay operating coil. The relay contacts are closed

and the circuit breaker is energised to open the contacts of the circuit breaker.

MAINTENANCE OF 400 KV SUB-STATION

In order to ensure smooth & safe operation of the substation, it is essential to keep all the

equipments of switchyard, protection relays and auxiliaries in healthy condition all the

time so that we can attain high level of availability which is more than 98.5%. There are

various maintenance activities for different equipments in order to keep them in healthy

condition. Details of various schedule maintenance activities are as given below:

MONTHLY MAINTENANCE ACTIVITIES FOR EQUIPMENTS: (WITHOUT

SHUTDOWN)

TRANSFORMER & REACTOR:

i) Checking of bushing oil level.

ii) Checking of oil level in conservator.

iii) Checking of oil level in OLTC conservator.

iv) Checking of cooling pump & fans (manual actuation).

v) Checking of oil leaks.

vi) Checking of Silica gel condition in breather.

vii) Checking of oil level in oil seal of breather.

CIRCUIT BREAKER:

i) Checking of oil leaks from grading capacitors.

ii) Checking of oil leaks in hydraulic circuit.

iii) Checking of hydraulic oil level & replenishment/ topping up of oil (if

necessary).

CURRENT TRANSFORMER:

i) Visual inspection of CT for oil leakage and crack in insulator etc.

ii) Checking of oil leakage in Terminal Box of CT MB.

iii) Checking of healthiness of gasket of CT MB.

CAPACITOR VOLTAGE TRANSFORMER:

i) Checking of oil leakage.

ii) Measurement of secondary voltage measurement in S/Y MB.

PROTECTION SYSTEM:

i) Testing of DR/EL with Time Synchronisation Unit.

HALF YARLY MAINTENANCE OF EQUIPMENTS (WITHOUT S/D):

TRANSFORMENR AND REACTOR:

i) Testing of oil for DGA and other oil parameters.

CIRCUIT BREAKERS:

i) Maintenance of Air Dryer of Pneumatic Operating Mechanism, if

provided.

YEARLY MAINTENANCE OF EQUIPMENTS (S/D ACTIVITY):

TRANSFORMENR AND REACTOR:

i) Check Auto Starting of cooler oil pumps and fans.

ii) Measurement of BDV of OILTC oil.

iii) External Cleaning of Radiator.

iv) Cleaning of all bushings.

v) Maintenance of OLTC driving mechanism.

vi) Checking of all remote indications (WTI & Tap position indicator)

vii) Electrical checking/testing of Pressure Relief Device, Buchholz relay,

OLTC surge relay and checking/ replacement of the gaskets of the

terminal box.

viii) checking/ testing of Buchholz relay by oil draining.

ix) Cleaning of MB, tightening of terminations and checking of contactors,

space heaters and illumination etc.

CIRCUIT BREAKER:

i) Checking of Hydraulic oil pressure drop/ air pressure drop during duty

cycle operation check.

ii) Checking of auto-starting/ stopping of oil pump/ air compressor.

iii) Dew point measurement of operating air at the outlet of Air

Dryer for

ABCB breaker.

iv) CB operating timings (Main, PIR, Aux.)

v) Checking of Pole Discrepancy relay.

vi) Functional checks, duty cycle operation including rapid re-closing

(O-0.3s-CO).

vii) Checking of all operation lockouts.

viii) Checking of all interlocks.

ix) Checking of pressure settings.

x) Cleaning of Breaker interrupter, support insulators, PIRs and grading

capacitors.

xi) Checking of close/trip coil currents.

xii) Checking of healthiness of Operation Counter.

xiii) Checking of tightness of all cable terminations in MB.

xiv) Checking of door sealing gaskets and replacement, if necessary.

xv) Checking of space heaters.


i) Thermovision scanning of CT and Top dome.

ii) Checking of space heaters & illumination in CT MB.

iii) Checking the tightness of all connections including earthing.

iv) Cleaning of marshalling box and junction box.


i) Visual checking of earthing HF point (in case it is not being used for

PLCC).

ii) Checking for any breakage or cracks in cementing joint.

iii) Cleaning of CVT capacitor stacks and tightness of terminal

connections.

iv) Thermovision scanning of capacitor stacks and EMU.

v) Checking of space heaters & illumination of MB.

vi) Checking and tightness of all connections including earth connections.

vii) Cleaning of MB and junction box & checking the healthiness of

gaskets.

ISOLATORS AND EARTH SWITCHES:

i) Linkages including transmission gears of operating mechanism.

ii) Stopper bolt.

iii) Cleaning of aux. switch contacts.

iv) Lubrication of operating mechanism, hinges, levers, bearing.

v) Checking of all mounting bolts for tightness.

vi) Cleaning and lubrication of main & earthing blades.

vii) Alignment of main & earth contacts.

viii) Checking of interlocks.

ix) Cleaning of support insulators and checking insulator cracks.

x) Checking of earth connections of structure and MOM box.

xi) Cleaning and terminal tightening in MOM box.

xii) Checking of space heater & illumination and checking of gaskets.

SURGE ARRESTOR:

i) Cleaning of LA insulator.

ii) Testing of counters.

iii) Checking of leakage current (Third harmonic Resistive current).

7. BUS-BAR, JUMPERS, CONNECTORS, CLAMPS ETC.

i) Measurement of station earth resistance.

ii) Thermovision scanning of all conductor joints, terminal connectors/

clamps.

iii) Checking of insulators for cracks.

iv) Cleaning of insulators

8. WAVE TRAP;

i) General inspection / cleaning of tuning unit.

ii) Tightening & cleaning of wave trap.

9. PROTECTION SYSTEMS:

i) Checking of DC logic circuit for trip and annunciations including

timers by simulation.

ii) Checking of voltage for relays.

iii) Reach checks for all 4 zones of Distance protection.

iv) Time measurement for the same.

v) Power swing blocking check for Distance protection.

vi) SOTF checking for Distance protection.

vii) VT fuse failure check for Distance protection.

viii) Checking of trip contacts and annunciations.

ix) Check for carrier send.

x) LBB and STUB protection testing.

xi) Auto Reclose test.

xii) Checking of DR & EL initiation.

xiii) Checking of fault locator initiation.

xiv) Checking of Over voltage relay.

xv) Checking of all aux. relays.

xiv) Checking of Reactor back up impedance.

xv) Checking of Buchholz, PRV OTI, WTI in reactor and transformer.

xvi) Checking of differential protection of reactor and transformer.

xvii) Checking of REF Protection of reactor and transformer.

xviii) Checking of Over Fluxing and over load relay in transformer.

xix) Checking of PLCC system for return loss, transmitter/ receiver

check, power supply measurement and alarms.

TWO YEARLY MAINTENANCE OF EQUIPMENTS (S/D ACTIVITY):

TRANSFORMER AND REACTORS:

i) C & Ten delta measurement of bushings.

ii) Vibration measurement of reactors.

iii) Checking and calibration of WTI & OTI.

CIRCUIT BREAKER:

i) Static Contact Resistance measurement.

ii) Dynamic contact Resistance measurement.


i) Measurement of C & tan delta.

THREE/ FOUR YEARLY MAINTENANCE OF EQUIPMENTS (S/D ACTIVITY):

TRANSFORMER AND REACTOR:

i) IR measurement of transformer winding.

ii) C & Tan delta measurement of transformer winding.

iii) Winding resistance measurement of transformer at all tap position.

CIRCUIT BREAKER:

i) C & Tan delta measurement of grading capacitor.

ii) Dew point measurement of SF6 gas (3Y).


i) C & Tan delta measurement (3Y).

ISOLATORS AND EARTH SWITCH:

i) Contact resistance measurement of main and earth contacts.

SOS ACTIVITIES FOR EQUIPMENTS:

TRANSFORMER AND REACTORS:

i) Measurement of windings ratio.

ii) Measurement of short circuit impedance.

iii) FRA measurement.

iv) Checking and cleaning of diverter contacts.

v) Filtration/ replacement of OLTC oil.

vi) Filtration/ degassing of main tank oil.

vii) IR measurement of bushing CTs.

CIRCUIT BREAKER:

i) SF6 gas/ Air pressure leakage test.

ii) Repainting of metallic part.


i) IR measurement.

ii) Measurement of CT secondary resistance, CT ratio test.

iii) Magnetization characteristics.

iv) DGA and other parameters of oil.


i) Testing of EMU tank oil for BDV (if oil found discoloured).

BUS-BAR, JUMPERS, CONNECTORS, CLAMPS, S/Y ILLUMINATION

ETC.:

i) Removal of hot spots.

ii) De-weeding of switchyard.

iii) Repainting, rust removal of all structures, equipments etc.

iv) Checking of Switchyard lighting.

BUS BAR PROTECTION:

i) Primary injection test and protection stability and sensitivity checks.

(To be done whenever the protection AC circuits are disturbed like

addition of new feeder)

MONTHLY MAINTENANCE ACTIVITIES FOR AUXILIARIES:

BATTERIES AND DC DISTRIBUTION SYSTEM:

i) Measurement of Specific Gravity and voltage of cell

ii) Checking of electrolyte level and topping up with DM water, if

required.

iii) Checking of Emergency DC lighting to control room.

iv) Checking of any earth fault (if E/F relay not provided).

DG SET:

i) Checking of oil leakage from lubricating system.

ii) Check for radiator air blocking and coolant level.

iii) Check for air leaks for air intake system.

iv) Battery voltage and specific gravity measurement.

FIRE PROTECTION SYSTEM:

i) Sequence test for annunciation in Control room panel for fire alarm

system.

ii) Smoke test and cleaning of detectors.

iii) Checking / replacement of air filters of compressor.

iv) Checking of auto starting of diesel engine.

v) Checking of oil level of diesel engine, top up if required.

vi) Check leakage and lubrication of all the pumps.

vii) Checking of operation of all the pumps and compressor.

AIR CONDITIONING PLANT:

i) Checking of belt tension and safety guard alignment of compressors.

ii) Checking of leakage for refrigerant and oil of compressor.

iii) Checking of oil compressor oil level, top up if required.

iv) Checking of water leaks.

v) Checking operation of inlet and outlet valves.

vi) Cleaning of soft water tank and regeneration of chemicals.

vii) Cleaning of cooling tower.

QUARTERLY MAINTENANCE ACTIVITIES FOR AUXILIARIES:


i) Checking of compressor oil and replace if necessary.

ii) Maintenance & cleaning of compressor valves, gaskets, valve plates.

iii) Operation check of low oil level switch.

iv) Checking of belt tightness and cleaning of oil strainer.


i) Checking of tightness of flywheel, bolted joints, leakage of oil etc.

ii) Cleaning of cooling tower nozzles for clogging.

iii) Flow switch performance checking.

iv) Cleaning of suction air filters of AHU.

HALF YEARLY MAINTENANCE ACTIVITIES FOR AUXILIARIES:

1. FIRE FIGHTING SYSTEM:

i) Checking of terminal connection of all motors.

ii) Adjustment of gland of all pumps for leakages and tightening of nuts

and bolts.

iii) Greasing of all valves.

D.G.SET:

i) Cleaning of air filters of Air Intake system.

ii) Checking of electrical connections for tightness of main generator.


i) Checking of water pressure of condenser unit and cleaning of side

plates.

ii) Checking operation of level switch.

iii) Checking water quality.

iv) Lubrication of all moving parts of motors and pumps.

v) Checking of terminal checking of motors.

YEARLY MAINTENANCE ACTIVITIES FOR AUXILIARIES:

BATTERIES AND DC DISTRIBUTION SYSTEM:

i) Checking of electrical connections of charger panel & DCDB panels

for tightness and cleanliness.

ii) Checking of electrical connections for Batteries and application of

petroleum jelly on cell terminal, if required.

iii) Checking control cards of charger & measurement of test point

voltage values.

iv) Battery impedance testing.

v) Testing of DC E/F and under voltage relays.

vi) IR measurement of charger transformer.

vii) Discharge test of Battery set (3Y).


i) Cleaning of HP tank.

ii) Cleaning of NRVs.

iii) Checking/replacement of fuel oil filter, lub oil filter, air filter of Diesel

engine.

iv) Checking of alignment of all pump sets.

v) Checking of pressure of the hydrant system at the remotest end, auto-

starting of pumps, diesel engine etc.

vi) Operation of Deluge system, check outlet pressure check alarm, check

starting of diesel/ electrical pump.

vii) Cleaning and tightening of terminals of electrical panels.

viii) Painting of pipes, air lines MB.

DG SET:

i) Replacement of oil filters, lub.oil filters, air filters.

ii) Checking for cooling fan hub, drive pulley and water pump.

iii) Checking of governor linkages, fuel transfer pump, fuel line

connections.

iv) Drain sediments from fuel tank and clean fuel tank breather.

v) IR measurement of Stator winding & testing of protection relays &

alarms.

vi) Checking/ cleaning of slip ring and its brushes.

vii) Check for air leaks and exhaust restrictions & tight exhaust manifold.

LT SWITCHGEAR, LT TRANSFORMER, LT PANEL ETC.:

i) Cleaning and checking of panels, bus bar insulators etc.

ii) Relay testing.

iii) Tightness of all electrical connections and all indication meters.

iv) Check for change-over facility if provided.

v) Check operation/ indications in Off-load condition of Air CB.

vi) Check spring charging of CB.

vii) Functional checking (trip, close etc) of 33/11 KV CBs.

viii) Testing of LT transformer oil BDV, IR measurement and testing of

WTI,OTI and Buchholz relay (if provided).

ix) Measurement of operating timings (3Y).


ii) Checking of oil pressure switch, LP/HP, cut-out switches,

solenoid valve, thermostat, humidistat etc of compressor.

ii) Cleaning of Bus bars, insulators of electrical panels.

iii) Tightness of electrical connections.

SOS ACTIVITIES FOR AUXILIARIES:

1. FIRE PROTECTION SYSTEM:

i) General overhaul of compressor.

ii) Overhauling of pumps & replacement of grease in pumps.

iii) Re-filling of Fire Extinguishers.

2. AIR CONDITIONING PLANT:

i) De-scaling of condenser unit and cooling water circuit.

MAINTENANCE OF FACTS:

FACTS installed on 400 KV BLB-KNP line is first project on any 400 KV lines

in India. For the maintenance of FACTS some precautions has to be taken as capacitor

bank and all other equipments are installed on a platform, charged at 400 KV.

PRECAUTIONS TO BE OBSERVED WHILE WORKING ON THE HIGH

VOLTAGE PLATFORM

All equipment on the platform need to be de-energized disconnected from the

supply and grounded and un-authorized re-enerrgisation shall be prevented before any

work is started.

1. Bypass the capacitor bank permanently (both earth switches will be closed under

this condition, both capacitor isolators are open, bypass isolator and BPCB is

closed).

2. Open the fence door observing all capacitor isolator interlock protocol.

3. Using an earth rod, manually earth all incoming tube connections from line for all

the phases. Also, earth all the platforms manually by earthing rod. Keep the earth

rod permanently connected on that platform on which work will be undertaken.

4. Do not work on the platform when it is drizzling or raining or under conditions of

thunder and fog.

5. After completing work on platform remove earthing rod, ladders, loose hardware

and working tools lying on platform or inside platform mounted equipment.

Ensure all doors of platform mounted equipment are properly closed.

6. Ensure all maintenance personnel have vacated the fenced area.

7. Close fence door observing all interlock protocol.

8. No isolator is to be opened or closed unless BPCB is closed.

PREVENTIVE MAINTENANCE SCHEDULE FOR METAL OXIDE VARISTOR (MOV)

HALF YEARLY MAINTENANCE:

1. Visual Inspection

2. Check for any bulging of Pressure Relief Diaphragm

3. Check for cleanliness of insulator surface and clean if required

THREE YEARLY MAINTENANCE:

1. Check electrical and mechanical connections and re-torque if required

Note: Visual inspection need to be carried out after each line fault at the first

available opportunity.

PREVENTIVE MAINTENANCE SCHEDULE FOR CAPACITOR BANK

YEARLY MANITENANCE:

2. Visual inspection of bank for pollution, painting damages or leaking capacitor

units and cleaning if necessary. (If capacitor is damaged and starts leaking, it is to

be replaced. However small leaks can be repaired with epoxy adhesive)

3. Check the settings and operation of the protective relays.

4. Tightening of all connectors (including the connectors on housing studs) with

optimum torque (20Nm).

5. Check the unbalance current. (If the unbalance current exceeds 50% of the

tripping value, undertake measurement of capacitance of all capacitor units in the

bank and faulty units be replaced. Measurement is applicable where ever

provision is available.)


I. Measurement of Capacitance of all capacitor units. (If the measurement of a

capacitor unit indicates deviation beyond +/_5% compared to the values stated in

routine test report, the unit to be replaced)

PREVENTIVE MAINTENANCE SCHEDULE FOR SPARK GAP:

YEARLY MANITENANCE:

I. Check for cleanliness and any mechanical damage to the enclosure, support

insulators.

II. Check for burning mark on the surface of copper and graphite electrodes. (In case

of burning marks/ pitting they are to be smoothed by using a file and grinding

cloth and then cleaned by wiping with cloth.)

III. Check for tightness of bolted connections.

IV. Check for oil leakage in the voltage divider capacitor.

V. Measurement of capacitance of voltage divider capacitor to check voltage divider

ratio.

VI. Measurement of resistance of damping resistors.

FIVE YEARLY MAINTENANCE:

I. Measurement of flashover voltage of Trigatron.

PREVENTIVE MAINTENANCE SCHEDULE FOR SIGNAL COLUMN:

YEARLY MANITENANCE:

I. Visual inspection and cleaning of housing to remove any dust, dirt etc.

II. Checking of oil level.

III. Testing of oil.

IV. Checking colour of silica gel and replace silica gel if discoloration is observed.


I. Measurement of fibre optic cable attenuation.

PREVENTIVE MAINTENANCE SCHEDULE FOR AIR CORE REACTOR:

YEARLY MANITENANCE:

I. Visual inspection of the equipment and check if the arms of the top/bottom

spiders have become loose from the winding.

II. Check top and bottom of the winding for possible abnormalities such as

carbonization, arc marks etc.

III. Check top of the winding and the cooling ducts for foreign particles, in particular

for bird’s nests and remove them.

IV. Check inside and outside surface of the reactor winding for possible tracking

marks. If such marks are found notify before re-energisation.

V. Check tightening torque of the bolts of the support structure. If bolts are found to

be loose, re-tighten all the bolts.

VI. Check surface of the reactor and insulators for contamination. Clean reactors if

necessary.

VII. Check status of the protective paint of the reactor. Local imperfections or paint

peeling to be touched-up. (For usual environmental conditions it is recommended

that the reactor is r-coated after 10 years of operation).

रा�म प्रका�श मनो�ज गो�यल

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Documents

Pgcil Project Report