Standard Operating Procedure

Electrical Isolations
SOMC –VIZAG

Standard Operating Procedure

Electrical Isolations

SOP (Title) : Electrical isolation

SOP No. : SOMC/O&M/SOP/ Electrical isolation

Date:
Issue No. 1 Revision :00
09.10.2014

Department: Operation & Maintenance

Target group: Electrical Operators / Operation engineers

Approved by: DPM / GM

Released on:

Name Designation Signatur

e
Prepared Mr. Shishir Kanti Engineer
Das, Sr. Engineer
by Mr. Hari Prasad, Deputy Manager
Mr. Nanda Kumar
Mohan
Checked Mr. Sabu Isac Dy. Plant
Manager
by

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Reviewed Mr. Sabu Isac Dy. Plant

Manager
by

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Revision history log

Revision Revision date Revised by

Rev-0 09.09.2014 Mr. Shishir Kanti Das, Mr. Hari Prasad, Mr.
Nanda Kumar Mohan
Rev-1
Rev-2

Table of contents
Sl Description Page No
1 Purpose of the document 3
2 Scope of coverage 3
3 Definitions and abbreviations, specialized terms 3
used
4 Procedure- 400 kV isolations 4
5 Procedure – HT isolations 8
6 Procedure – LT isolations 10
7 Communication 12
8 Health and Safety Considerations 12
9 Approving Authority and Review 12
1 Data and Records Management 12
0

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1.0 Purpose of the document:

This document intends to provide step by step guidance for safe electrical operation of
400kV circuit breakers, 400kV Isolators and earth switches, HT and LT circuit breakers,
and LT electrical modules.

2.0 Scope of coverage:

The usage of this document is limited to isolation and normalization of 400kV breakers,
isolators & earth switches (applicable for 400 kV switchyard), HT breakers (applicable
for HT switchgear located at Unit-1 HT switchgear room, Unit-2 HT switchgear room,
AHP switchgear room and CHP switchgear room) and LT breakers and LT modules
(applicable for all LT switchgears located in the plant) located in the Vizag 2x520 MW
thermal power plant.

Personnel qualification
The electrical switchgear operating person shall be minimum ITI qualified with basic
understanding of electrical switchgear and undergone training on 400kV switchgear, HT
and LT switchgear isolation and normalization procedures.

3.0 Definitions and abbreviations, specialized terms used

AC : Alternating current
ACB : Air Circuit Breaker
AHP : Ash handling plant
BEB : Bus earthing breaker
Bkr : Breaker
CB : Circuit breaker
CHP : Coal handling plant
DC : Direct current
DCS : Distributed control system
EPB : Emergency push button
FEB : Feeder earthing breaker
HT : High Tension
LED : Light emitting diode
LT : Low Tension
MCB : Miniature circuit breaker
MFM : Multi function meter
PBS : Push button switch
PPE : Personal Protective Equipment
PTW : Permit to work
SAS : Switchyard automation station
SFU : Switch fuse unit
SS : Selector switch
TNC : Trip Neutral Close

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4 Procedure - 400kV Isolations

4.1 400kV circuit breaker opening procedure (from remote)

4.1.1 At breaker marshalling box, put the breaker Remote/Local selector switch in
remote mode and switch ON AC MCBs (MCB-1, MCB-2, MCB-3 and MCB-6)
and DC MCB (MCB-5)
4.1.2 In SAS, open the particular breaker mimic page.
4.1.3 Confirm the alarms are reset.
4.1.3 Select the breaker, a dialog box will appear.
4.1.4 Click OPEN in the dialog box and then click EXECUTE.
4.1.3 Observe that, the breaker indication turns green colour (from red colour)
indicating the breaker is open.
4.1.4 At local observe for, the particular breaker is in Open condition from
OPEN/CLOSE indicator.

4.2 400kV circuit breaker opening procedure (from local)

4.2.1 Open the breaker from SAS, if not opening, then follow the below procedure.
4.2.2 Open the circuit breaker marshalling box door.
4.2.3 Observe IL1-CB lamp is glowing indicating circuit breaker is CLOSE.
4.2.4 Ensure AC MCBs, MCB-1, MCB-2 and MCB-3 are in ON position, if not put in
ON position.
4.2.5 Ensure DC source MCB-5 and AC source MCB-6 are in ON position, if not
switch ON.
4.2.6 Put Local/Remote selector switch in local mode. If spring is not getting
charged then, follow 4.2.12.
4.2.7 Press Push button PBS1 (Green colour) and the circuit breaker operates.
4.2.8 Observe for IL2-CB lamp glowing indicating circuit breaker is OPEN. Inform
control room.
4.2.9 Switch off the breaker spring charging MCBs, MCB-1, MCB-2 and MCB-3 (for
each phase).
4.2.10Switch off 220V DC source MCB-5.
4.2.11Switch off AC source MCB-6.
4.2.12Manual spring charging procedure:
a. Switch off 220V DC source MCB-5.
b. Switch off MCB-1, MCB-2, MCB-3 and MCB-6.
c. Climb the ladder and open the mechanism box.
d. Insert rotating handle in the gap beside open/close dial where spring charging
indication label is given.
e. Insert handle straight in the male contact, rotate handle as indicated until the
spring charge / spring discharge indicator shows charge condition.
f. Take out the handle and place it in its designated place.

4.3 400kV circuit breaker closing procedure (from remote)

4.3.1 At breaker marshalling box, put the breaker Remote/Local selector switch in
remote mode and switch ON AC MCBs (MCB-1, MCB-2, MCB-3 and MCB-6)
and DC MCB (MCB- 5).
4.3.2 In SAS, open the particular breaker mimic page.

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4.3.3 Confirm the alarms are reset.

4.3.4 Select the breaker, a dialog box will appear.
4.3.5 Click CLOSE in the dialog box and then click EXECUTE.
4.3.6 Observe that, the breaker indication turns red colour (from green colour)
indicating the breaker is closed.
4.3.7 At local observe for, the particular breaker is in Close condition from
OPEN/CLOSE indicator.

4.4 400kV circuit breaker closing procedure (from local)

4.4.1 Go to respective breaker.
4.4.2 Open the circuit breaker marshalling box door.
4.4.3 Observe IL2-CB lamp is glowing indicating circuit breaker is OPEN.
4.4.4 Ensure AC MCBs, MCB-1, MCB-2 and MCB-3 are in ON position, if not put in
ON position.
4.4.5 Ensure DC source MCB-5 and AC source MCB-6 are in ON position, if not
switch ON.
4.4.6 Put selector switch (Remote/Local) in Local mode. If spring is not getting
charged, follow 4.4.10.
4.4.7 Press Push Button PBS2 (Red colour) button and the circuit breaker operates.
4.4.8 Observe for IL1-CB lamp glowing indicating circuit breaker is CLOSE.
4.4.9 Inform control room.
4.4.10Manual Spring charging and breaker closing procedure in Local Manual mode:
a. Switch off 220V DC source MCB-5.
b. Switch off MCB-1, MCB-2, MCB-3 and MCB-6.
c. Climb the ladder and open the mechanism box.
d. Insert rotating handle in the gap beside open/close dial where spring
charging indication label is given.
e. Insert handle straight in the male contact, rotate handle as indicated until
the spring charge / spring discharge indicator shows
charge condition.
f. Take out the handle and place it in its designated place.

4.5 400kV Isolator opening procedure (from remote)

4.5.1 Switch on the AC MCB and DC MCB in Isolator Master marshalling box
(located on R-phase structure) and put Local/Remote selector switch in
Remote position.
4.5.2 Put the Individual/Master control switch in Master mode.
4.5.3 In SAS, open the particular mimic page of the isolator to be opened.
4.5.4 Confirm the alarms are rest.
4.5.5 Select the isolator, a dialogue box will appear.
4.5.5 Click OPEN in the dialogue box and then click EXECUTE.
4.5.6 Observe that, the isolator indication turns green colour (from red colour)
indicating the isolator is opened.
4.5.7 At local observe for, the particular isolator is in physical OPEN condition.

4.6 400kV Isolator opening procedure (from local)

4.6.1 Open the Master marshalling box (located on R-phase structure) and put the
Local/ Remote selector switch S3 in local position.
4.6.2 Switch ON, AC power supply MCB & DC control supply MCB

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4.6.3 Ensure for castle key is in interlock position.

4.6.4 Put Master/Individual control switch in Master mode for gang operation.
4.6.5 Press the open push button.
4.6.6 Observe for smooth opening of the isolator. Ensure the finger contacts are
properly breaking the contact. If Isolator is not opening, then follow 4.6.9.
4.6.7 Inform control Room.
4.6.8 Switch OFF, AC power supply MCB & DC control supply MCB.
4.6.9 Isolator Manual Opening procedure:
a. Keep AC power supply MCB & DC control supply MCB.
b. By pressing the Push Button (PB), remove the castle key & keep the key
in handle lock (located at the side of marshalling box) and rotate so that
the inside flap moves away and provides way for inserting the operating
handle.
c. Insert the operating handle and rotate in clockwise for opening the
isolator phase.
d. Note that, in manual mode, the isolators can be opened pole wise but not
in gang operation.
e. Also, note that, the caste key is located only in R-Phase Master
marshalling box and same castle key to be used for other poles.

4.7 400kV Isolator closing procedure (from remote)

4.7.1 Switch on the AC MCB and DC MCB in Isolator Master marshalling box
(located on R- phase structure) and put Local/Remote selector switch
in Remote position.
4.7.2 Put the Individual/Master control switch in Master mode.
4.7.3 In SAS, open the particular mimic page of the isolator to be opened.
4.7.4 Confirm the alarms are rest.
4.7.5 Select the isolator, a dialogue box will appear.
4.7.5 Click CLOSE in the dialogue box and then click EXECUTE.
4.7.6 Observe that, the isolator indication turns red colour (from green colour)
indicating the isolator is closed.
4.5.7 At local observe for, the particular isolator is in physical CLOSE condition.

4.8 400kV Isolator closing procedure (From local)

4.8.1 Go to the respective isolator.
4.8.2 Open the door of the Master marshalling box located on R-phase structure.
4.8.3 Put Local/Remote selector switch S3 in local position.
4.8.4 Ensure MCB of DC control is ON, if not switch ON the same.
4.8.5 Ensure MCB of AC supply control is ON, if not switch ON the same.
4.8.6 Ensure castle key is in interlock position.
4.8.7 Put Master/Individual control switch in Master mode for gang operation.
4.8.8 Press the close push button.
4.8.9 Observe for closing of the isolator contacts. If isolator is not closing then
follow 4.8.11.
4.8.10Inform control room.
4.8.11Isolator Manual Closing procedure:
a. Switch OFF, AC power supply MCB & DC control supply MCB.
b. Keep AC power supply MCB & DC control supply MCB.

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c. By pressing the Push Button (PB), remove the castle key & keep the key
in handle lock (located at the side of marshalling box) and rotate so that
the inside flap moves away and provides way for inserting the operating
handle.
d. Insert the operating handle and rotate in anti-clockwise for closing the
isolator phase.
e. Observe for closing of the respective isolator pole.
f. Note that, in manual mode, the isolators can be closed pole wise but not
in gang operation.
g. Also, note that, the caste key is located only in R-Phase Master
marshalling box and same castle key to be used for other poles.

4.9 400kV Earth Switch opening procedure

4.9.1 Go to the respective earth switch.
4.9.2 Open the door of the Master marshalling box located on R-phase structure.
4.9.3 Ensure for MCB of DC control is ON, if not switch ON the same.
4.9.4 Ensure for MCB of AC control is ON, if not switch ON the same.
4.9.5 Put Master control switch in Master mode for gang operation.
4.9.6 Press the open push button.
4.9.7 Observe for opening of earth switch (all three poles earth switches open). If
earth switch not opening, follow 4.9.11.
4.9.8 Switch OFF AC control MCB.
4.9.9 Switch OFF DC control MCB.
4.9.10 Inform control room.
4.9.11 Earth Switch Manual opening procedure:
a. Switch OFF AC control MCB and DC control MCB.
b. Pressing the Push Button (PB), remove the castle key & keep the
key in handle lock (located at the side of marshalling box) and
rotate so that the inside flap moves away and
provides way for inserting the operating handle.
c. Insert the operating handle and rotate in clockwise for opening the
earth switch phase.
d. Observe for opening of the respective earth switch pole.
e. Also, note that, the caste key is located only in R-Phase Master
marshalling box and same castle key to be used for other
poles.

4.10 400kV Earth Switch closing procedure (Earth switch can be

operated only in Local mode)
4.10.1 Go to the respective earth switch.
4.10.2 Open the door of the Master marshalling box located on R-phase structure.
4.10.3 Ensure for MCB of DC control is ON, if not switch ON the same.
4.10.4 Ensure for MCB of AC control is ON, if not switch ON the same.
4.10.5 Put Master/Individual control switch in Master mode for gang operation.
4.10.6 Press the close push button.
4.10.7 Observe for closing of earth switch (all three poles earth switches close). If
not closing, follow 4.10.9.
4.10.8 Inform control room.
4.10.9 Earth Switch Manual Closing procedure:

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a. Switch OFF, AC control MCB & DC control MCB.

b. By pressing the Push Button (PB), remove the castle key & keep the
key in handle lock (located at the side of marshalling
box) and rotate so that the inside flap moves
away and provides way for inserting the operating handle.
c. Insert the operating handle and rotate in anti-clockwise for closing
the earth switch phase.
d. Observe for closing of the respective earth switch pole.
e. Also, note that, the caste key is located only in R-Phase Master
marshalling box and same castle key to be used for other
poles.

5 Procedure - HT Breaker isolations

5.1 HT circuit breaker rack out procedure (From service to test position)
5.1.1 Ensure circuit breaker in open (OFF) condition. Check green LED & Label
(thru transparent glass).
5.1.2 Switch “off” the DC control supply (SS2) located at control cubicle.
5.1.3 Free the truck lock pins (both side) on truck top by hand.
5.1.4 Using operating handle Turn the interlock from ‘locked’ position to ‘truck
free’ position.
5.1.5 By both hands Pull out the circuit breaker till it stops at test position.
5.1.6 Using operating handle Turn the interlock from ‘truck free position’ to
‘locked’ position.
5.1.7 Turn interlock back to truck locked position by operating handle (in this
position circuit breaker can be operated in test position).
5.1.8 Provide the PTW tag (with PTW no & name of PTW engr).
5.1.9 Lock the module and hand over the key to Control room /PTW receiver.

5. HT circuit breaker rack in procedure (From test to service

2 position)
5.2.1 Check and Remove the PTW tag (after ensuring for the closure of the
PTW) and Unlock the panel.
5.2.2 Ensure the DC is OFF (DC switch SS2 Off Located at control panel, all
indicating lamps are off).
5.2.3 Using operating handle, Turn interlock from ‘locked position’ to ‘free
position’.
5.2.4 Gripping both handle, Push breaker truck till it stops.
5.2.5 Turn interlock to ‘lock position’ by operating handle.
5.2.6 Lock truck lock pins on truck top at service position.
5.2.7 Close the breaker door and switch on (switch SS2) the DC supply
(indicating a lamp turns on).
5.2.8 Ensure the breaker in Service position (service position indicator and
indicating lamp). In case, spring is not getting charged, then follow
5.2.10.
5.2.9 Inform control room that Breaker is ready for operation from remote.

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5.2.10 Spring charging in manual mode:

a Insert the handle at manual crank and rotate clockwise until breaker
spring gets completely charged.
b Observe for spring charged indication on the breaker (flag indication) as
well lamp indication on panel.

5. HT Incomer isolation (for bus duct isolation)

3
5.3.1 Rack out the incomer breaker (Rack out breaker as per procedure 5.1)
5.3.2 Draw out the incomer breaker (Draw out the breaker as procedure 5.6)
5.3.3 Insert FEB (Feeder Earthing Breaker) truck (As per procedure 5.2).
5.3.4 Switch “ON” the DC control supply.
5.3.5 Close the FEB breaker by push button on feeder control panel.

5. HT Incomer isolation (for bus bar isolation)

5
5.5.1 Rack out the incomer breaker (as per procedure 5.1).
5.5.2 Draw out the incomer breaker (as procedure 5.6).
5.5.3 Insert BEB (Bus Earthing Breaker) truck (As per procedure 5.2).
5.5.4 Switch “ON” the DC control supply.
5.5.5 Close the BEB breaker by push button on feeder control panel.

5. HT Incomer isolation Normalization

5
5.5.1 Rack out the FEB/BEB Breaker (refer procedure 5.1 for Rack out).
5.5.2 Draw out the FEB/BEB Breaker (Refer procedure 5.6).
5.5.3 Insert the original (Incomer) circuit breaker (refer procedure 5.7).
5.5.4 Rack in the Breaker (refer procedure 5.2).

5. Drawing the Breaker out of the Cubicle

6
5.6.1 Ensure circuit breaker in Open (OFF) condition (Check green LED & Label
–thru transparent glass).
5.6.2 Switch OFF the DC control supply SS2.
5.6.3 Ensure the breaker interlock in locked position.
5.6.4 Disengage the breaker control supply plug from socket.
5.6.5 Discharge the spring (Close and Open the breaker mechanically).
5.6.6 Gripping both handle Pull the circuit breaker truck into cubicle up to test
position.
5.6.7 Lock the cubicle door.

5. Inserting the Breaker which is outside the cubicle

7
5.7.1 Check & verify Breaker rating.
5.7.2 Ensure circuit breaker in Open (OFF) condition (Check thru Open / Close
label located at breaker front).
5.7.3 Discharge the spring (Close and Open the breaker mechanically).

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5.7.4 Ensure the breaker interlock in locked position.

5.7.5 Gripping both handle Push the circuit breaker truck into cubicle up to test
position.
5.7.6 Engage the breaker control supply plug into the socket.
5.7.7 Switch on (SS2) DC control supply.
5.7.8 Ensure that the Breaker is in Test position (LED indication).
5.7.9 Check the breaker healthiness in test position through TNC Switch (spring
charge, feedback for local & DCS).
5.7.10 Rack in the Breaker (Refer Rack in procedure 5.2).

5. Interchanging of circuit breaker

8
5.8.1 Rack out & draw out the Faulty circuit breaker (refer procedure 5.1 &
5.6).
5.8.2 Identify the new breaker (verify current rating).
5.8.3 Rack out & draw out the new circuit breaker (refer procedure 5.1 & 5.6).
5.8.4 Shift the New breaker.
5.8.5 Insert the new breaker (refer procedure 5.7).

6 Procedure - LT Breaker isolations

6. LT Incomer ACB Breaker – Isolation Procedure

1
6.1.1 Ensure ACB circuit breaker in open (OFF) condition (current in ammeter,
MFM and Relays are zero) and OFF LED lamp glows.
6.1.2 Open the Control panel door, Switch “OFF” the DC control supply located
at Breaker Control cubicle (Switch off Main DC Switch S1).
6.1.3 Rotate the locking nuts anti-clockwise for releasing the mechanical locks
provided at both left and right sides of the breaker.
6.1.4 Press the locking lever downside for releasing the mechanical locks
provided at both left and right sides of the breaker.
6.1.5 Press the 'OFF' Mechanism push button and engage the handle in the
breaker for racking out the breaker.
6.1.6 Rotate the breaker handle anti-clockwise until the breaker reaches the
isolated position. And remove the handle from the breaker.
6.1.7 Close the panel door and Lock the Module and hand over the key to
Control room / PTW receiver.
6.1.8 Provide the PTW tag (with PTW no & name of PTW engr).

6. LT Incomer ACB Breaker – Normalization Procedure

2
6.2.1 Ensure the permit to work has been cancelled.
6.2.2 Remove the Danger Tag and open the module door.
6.2.3 Ensure ACB circuit breaker in open (OFF) condition at breaker mechanism
lever.
6.2.4 Press the OFF Mechanism push button and engage the handle in the
breaker for racking in the breaker.

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6.2.5 Rotate the breaker handle clockwise until the breaker reaches the service
position. And then remove the handle from the breaker.
6.2.6 Rotate the locking nuts clockwise for locking the mechanical locks
provided at both left and right sides of the breaker.
6.2.7 Switch “ON” the DC control supply located at Breaker Control cubicle
(Switch ON Main DC Switch S1). And Ensure Control Supply Healthy, Bkr
Open, Bkr in Service, Trip circuit healthy and Spring Charge Healthy LED
indications glowing. If spring is not getting charged, follow 6.2.11.
6.2.8 Close the Panel door.
6.2.9 Now the circuit breaker can be operated in remote mode.
6.2.10 Remove the PTW tag and Inform Control Room.
6.2.11 Spring charging in manual mode:
a Ensure the flag of ACB indicates spring uncharged.
b Ensure the ACB in service position.
c Insert the spring handle, charge the spring manually until the flag of ACB
indicates spring charged.

6. LT Feeder ACB Breaker – Isolation Procedure

3
6.3.1 Ensure ACB circuit breaker in open (OFF) condition and Ensure the
equipment is stopped (current in ammeter, MFM and Relays are zero) and
OFF LED lamp glows.
6.3.2 Confirm whether the EPB is pressed.
6.3.3 Open the Module door, Switch “OFF” the DC control supply located at
Breaker Control cubicle (Switch off Main DC Switch S1).
6.3.4 Rotate the locking nuts anti-clock wise for releasing the mechanical locks
provided at both left and right sides of the breaker.
6.3.5 Press the locking lever downside for releasing the mechanical locks
provided at both left and right sides of the breaker.
6.3.6 Press the off Mechanism push button and engage the handle in the
breaker for racking out the breaker.
6.3.7 Rotate the breaker handle anti-clockwise until the breaker reaches the
isolated position. And remove the handle from the breaker.
6.3.8 Close the panel door and Lock the Module and hand over the key to
Control room / PTW receiver.
6.3.9 Provide the PTW tag (PTW no & name of PTW engr).

6. LT Feeder ACB Breaker – Normalization Procedure

4
6.4.1 Ensure the permit to work has been cancelled.
6.4.2 Remove the Danger Tag and open the module door.
6.4.3 Ensure ACB circuit breaker in open (OFF) condition at breaker mechanism
lever.
6.4.4 Open the front Module door and Press the OFF Mechanism push button
and engage the handle in the breaker for racking in the breaker.
6.4.5 Rotate the breaker handle clockwise until the breaker reaches the service

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position. And then remove the handle from the breaker.

6.4.6 Rotate the locking nuts clockwise for locking the mechanical locks
provided at both left and right sides of the breaker.
6.4.7 Switch “ON” the DC control supply located at Breaker Control cubicle
(Switch ON Main DC Switch S1). And Ensure Control Supply Healthy, Bkr
Open, Bkr in Service, Trip circuit healthy and Spring Charge Healthy LED
indications glowing.
6.4.8 Close the Panel door.
6.4.9 Now circuit breaker can be operated in remote mode.
6.4.10 Remove the PTW tag and Inform Control Room.

6. LT Feeder (SFU module) – Isolation Procedure

5
6.5.1 Ensure the equipment is stopped (current in ammeter is zero) and 'OFF'
LED lamp glows.
6.5.2 Press the EPB at local.
6.5.3 Switch 'OFF' Isolator by operating handle.
6.5.4 Open the Module door, confirm SFU needle is 'OFF' position.
6.5.5 Remove the control fuse.
6.5.6 Using fuse puller Remove the power fuse and keep in fuse box.
6.5.7 Provide the PTW tag (with PTW no & name of PTW engr).
6.5.8 Close the panel door and Lock the Module and key handed over to
Control room/ PTW receiver.

6. LT Feeder (SFU module) – Normalization Procedure

6
6.6.1 Ensure the permit to work has been cancelled.
6.6.2 Remove the Danger Tag and open the module door.
6.6.3 Open the Module door; confirm SFU needle is in 'OFF' position.
6.6.4 Using fuse puller Insert the power fuse. Ensure the healthiness of the fuse
and its rating.
6.6.5 Put the control fuse (check for healthiness and its rating).
6.6.6 Close the Panel door.
6.6.7 Check the LED indication lamps are glowing (OFF indication).
6.6.8 Switch 'ON' the Isolator and Inform Control Room.

7.0 Communication
a. When a PTW is being issued on the equipment, the issuer instructs the control
person (electrical operator / operation engineer) for isolation of the breaker /
module.
b. The communication between PTW issuer and electrical operator / operation
engineer shall be through Public Address (PA) System / Telephone / Walkie-Talkie
/ Mobile Phone.

8.0 Health and Safety Considerations

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a. Always use PPE like safety shoes, safety helmet, rubber mats, electrical safety
hand gloves, etc.
b. Umbrella shall never be carried in switchyard.
c. The electrical activities to be performed only by using the designated tools like
breaker door opening keys, breaker rack out levers, spring charging levers, etc.
d. The Electrical works are performed by qualified persons under continuous
supervision.
e. Ensure that breaker / module doors are kept closed.

9.0 Approving Authority and Review

Document shall be reviewed and approved for adequacy by the Head of Project /CEO
prior to issue.
The document shall be reviewed after every 1-2 years or as and when required.

10.0 Data and Records Management

The Master copy of the SOP shall be maintained with MTP department (library).
Record of all isolations done shall be entered in PTW register and in log book.
The PTW registers shall be kept in control room. When pages are filled the same shall
be deposited with MTP.

Ref: SOMC/O&M/SOP/ Electrical isolation Page 14 of 14

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