MADHYA PRADESH POORV KSHETRA VIDYUT VITARAN … Folders/Jabalpur... · operation of 33 KV...

MADHYA PRADESH POORV KSHETRA

VIDYUT VITARAN COMPANY LTD.

MAINTENANCE MANUAL FOR OPERATION

2019

Contents

1. Introduction to Electricity Distribution System ..................................................................... 3

2. Authorized Person for Maintenance Work Execution ........................................................... 5

3. Maintenance of 33 KV Sub-Transmission System ................................................................ 8

4. Maintenance of HT Consumer’s Premises .......................................................................... 11

5. Maintenance Of 33/11 Kv Substation .................................................................................. 12

6. Instructions for operator of 33/11 KV S/s in respect of various Alarms ............................. 13

7. Pre-monsoon and post monsoon maintenance and check list thereof ................................. 15

8. Maintenance Power Transformer ......................................................................................... 22

9. Operation and Maintenance of 11 kV 600 KVAR Capacitor Bank .................................... 25

10. Operation and Maintenance of 11 kV 1200 KVAr Capacitor Bank .................................... 26

11. Reconditioning of Power Transformer ................................................................................ 27

12. Procedure for replacement / repairing of failed Power Transformer ................................... 28

13. Maintenance Of 11kV Primary Distribution System:- ........................................................ 40

14. Maintenance of 11/0.4 kv Distribution Transformer ........................................................... 42

15. Maintenance of LT Distribution System .............................................................................. 46

16. Chart of safe clearances ....................................................................................................... 50

17. Breakdown management and Disaster management ........................................................... 51

18. SAFETY FORM .................................................................................................................. 58

19. Sub Permit Safety Form ....................................................................................................... 60

1. Introduction to Electricity Distribution System

Power distribution system under the control of Madhya Pradesh Poorv Kshetra Vidyut

Vitaran Company starts from the outgoing points of EHV Substations at 33 KV or 11 KV

System. 33 KV Sub-transmission system is feeding power supply to the HT Consumers and

33/11 KV Substations. 11 KV Primary Distribution system is emanating from 33/11 KV

Substations feeding power supply to HT Consumers and 11000/440-220 volts Distribution

transformers for supply to LT Three Phase and Single-Phase consumers. System’s Indicating

sketch as below is explaining the Power Distribution System.

Image 1: Simplified Electrical Power Transmission System

Image 2: Schematic Distribution Diagram

In order to maintain continuity of supply as per demand and requirement of Power,

Distribution System is considered for maintenance in sections as under: -

1. 33 KV Sub-Transmission System.

2. 33/11 KV Substations.

3. 11 KV Primary Distribution System.

4. 11/0.4 KV Distribution Substations.

5. L.T. Distribution System.

2. Authorized Person for Maintenance Work Execution

Regional Chief Engineers are empowered to sanction 1500 Man-days per City/(O&M)

Divisions per year for maintenance of the Distribution System as defined above. Above 1500

Man-days with line staff and help of local bodies as Nagar Nigam for tree branches trimming

etc., maintenance works are to be carried out.

S.

No.

Designati

on

Responsible Officer Description of works for which He is Authorized.

1. EE/AE/JE

.

Supdt.

Engineer.

1. Authorized to receive/issue permit to work on Dead up to 33

KV line or equipments isolated from all source of supply,

earthed, discharged, and short circuited and carry out the

work under his supervision with strict compliance of Safety

procedures and rules.

2. Line

Inspector. Executive

Engineer.

1. Authorized to receive permit to work on Dead 11 KV line or

equipments isolated from all source of supply by authorized

person, earthed, discharged, and short circuited and carryout

the work under his supervision with strict compliance of

Safety procedures and rules.

2. Authorized to carry out the work under his supervision on LT

line or equipment upto 440 VAC with strict compliance of

Safety procedures and rules.

3.

Line

Man/

Asstt Line

Man.

Assistant

Engineer/

Junior

Engineer.

1. Authorized to receive permit to work on Dead 11 KV line or

equipments isolated from all source of supply by authorized

person, earthed, discharged, and short circuited and carryout

the work under Authorized person’s supervision with strict

compliance of Safety procedures and rules.

2. Authorized to work on LT line or equipment up to 440 VAC

with strict compliance of Safety procedures and rules.

4. Line

Helper.

Junior

Engineer.

1. Authorized to work under supervision of Line Man/Assistant

Line Man/ Line Inspector/ Junior Engineer or any authorized

person on Dead, earthed LT line or equipment upto 440 VAC

for Fuse replacement Bulb replacement work with strict

compliance of Safety procedures and rules.

2. Authorized to work on Meter Board, Switch, Cutout,

Substation Switch fuse replacement. But he shall be

responsible to work with strict compliance of Safety

procedures and rules.

Note: -

1. Line Man/Asstt Line Man individually posted in rural area are authorized to work on line

upto11000 volts after isolating the A.B. Switches, providing locks, Discharging, Earth

connecting for urgent work of fuse replacement etc. But he shall be solely responsible to

work with strict compliance of Safety procedures and rules.

2. Line Helpers having experience of line maintenance work of 10 years may be authorized by

EE to work on line up to 11000 volts after isolating the A.B. Switches, providing locks,

Discharging, Earth connecting for urgent work of fuse replacement etc. But he shall be solely

responsible to work with strict compliance of Safety procedures and rules.

2.1. Responsibility for Issue of permit to work on line or equipments

Permit to work on line or equipments shall be issued to the Engineer or Line Inspector by

the Substation Operator under the responsibility and supervision of Substation’s OIC after

isolation of the line or equipments from the main source and obtaining Not to Back Feed permits

from all possible alternate sources and affixing the Caution Board that “Caution Do Not Close

Men on work”.

2.2. Responsibility for maintenance and Operation of Distribution System

Regional Chief Engineer shall be responsible for continues monitoring of maintenance and

operation of 33 KV Sub-transmission system. Maintenance of 33 KV line and Bus of 33/11 KV

Substation shall be carried out by (O&M) wing and maintenance of 33/11 KV Substation

equipments, Power Transformer etc. shall be carried out by STM wing.

Regional Chief Engineer shall be responsible to ensure maintenance of 33 KV Sub-

transmission system completed up to 30th May of every year.

Regional Chief Engineer shall be responsible to ensure submission of consolidated report

of33 KV Sub-transmission system’s maintenance up to 30th June of every year to the ED/CE

Corporate Office.

Corporate Office will depute team for verification of maintenance work and quality by

sample check after receiving the Sub-transmission system’s maintenance report from Regional

Chief Engineers.

Superintending Engineer of the Circle shall be responsible for continues monitoring of

maintenance and operation of 11 KV Primary Distribution system. Maintenance of 11 KV line

and DTRs shall be carried out by (O&M) wing.

Superintending Engineer shall be responsible to ensure maintenance of 11 KV system

completed up to 30th June of every year.

Superintending Engineer shall be responsible to ensure submission of consolidated report of

11 KV Sub-transmission system’s maintenance up to 25th July of every year to the Regional

Chief Engineer Office.

Regional Chief Engineer Office will depute team for verification of maintenance work and

quality by sample check after receiving the 11 KV system’s maintenance report from

Superintending Engineer. Further Regional Chief Engineer shall be responsible to ensure

submission of consolidated report of 11 KV system’s maintenance up to 30thJuly of every year

to the ED/CE Corporate Office.

Executive Engineer of the (O&M)/City Division shall be responsible for continue monitoring

of maintenance and operation of DTRs and LT Distribution system. Maintenance of DTRs and

LT Distribution system shall be carried out by (O&M) wing.

Executive Engineer shall be responsible to ensure maintenance of DTRs and LT Distribution

system is completed up to 30thJune of every year.

Executive Engineer shall be responsible to ensure submission of consolidated report of DTRs

and LT Distribution system’s maintenance up to 25thJuly of every year to the Superintending

Engineer Office.

Superintending Engineer Office will depute team for verification of maintenance work and

quality by sample check after receiving the DTRs and LT Distribution system’s maintenance

report from Executive Engineer. Further Superintending Engineer shall be responsible to ensure

submission of consolidated report of DTRs and LT Distribution system’s maintenance up to

30thJuly of every year to the Regional Chief Engineer who will submit to ED/CE Corporate

Office.

2.3. Time limit for restoration of supply after Breakdowns

Responsible concerned Engineers in general shall ensure restoration of supply within time

limit after Breakdowns as under:-

1. 33 KV Supply shall be restored within 2 Hrs., after breakdown in Urban / Town area

(When support of line is not damaged).

2. 33 KV Supply shall be restored within 4 Hrs., after breakdown in Rural area (When support

of line is not damaged).

3. Failed Power Transformer shall be replaced within 24 Hrs., in Area Store Head Quarter area.

4. Failed Power Transformer shall be replaced within 48 Hrs., in other than Area Store Head

Quarter area.

5. 11 KV Supply shall be restored within 4 Hrs., after breakdown in Urban/Town area (When

support of line is not damaged).

6. 11 KV Supply shall be restored within 6 Hrs., after breakdown in Rural area in day light

hours (When support of line is not damaged).

7. Failed Distribution Transformer shall be replaced within 24 Hrs., in Urban/Town

area.

8. Failed Distribution Transformer shall be replaced within 48 Hrs., in rural area.

9. LT Supply shall be restored within 4 Hrs., after breakdown in Urban/Town area (When

support of line is not damaged).

10. LT Supply shall be restored within 8 Hrs., after breakdown in Rural area in day light hours

(When support of line is not damaged).

11. In case of any delay in restoration of supply as indicated above, concerned Executive engineer

shall be responsible to submit the detailed report on the breakdown through Superintending

Engineer to Regional Chief Engineer. Regional Chief Engineer shall submit said report to

Corporate Office with affixing the responsibility on delay caused for restoration of supply.

3. Maintenance of 33 KV Sub-Transmission System

Regional Chief Engineer and Superintending Engineer City/(O&M) shall be responsible for

maintenance and continue operation of 33 KV Sub-Transmission System.

3.1. Preventive Maintenance

In consideration of expected breakdowns in monsoon and natural disturbances, Pre-Monsoon

and Post Monsoon maintenance is necessary for weak insulator replacement, resagging of loose

conductors, rebinding, and clearance maintenance of conductors as per standards from

trees/pole/guarding/ground level etc. to avoid the breakdowns. Action to be ensured as under:-

1. Superintending Engineer City/(O&M) shall be responsible for coordination with local

bodies for obtaining the services of tree pruning etc. and engineers under him to decide

programs for maintenance work of 33 KV Sub-Transmission System.

2. According to the predefined programs, Shut-Down Notice in advance of 48 Hours is to be

issued to the HT Consumers and consumers of effected area through News Papers and

Media services etc. Supply from 33/11 KV Substations having alternate 33 KV supply

source may be arranged by alternate source for power supply if possible.

3. According to the predefined programs, patrolling teams shall be allotted for patrolling the

line maintenance in sections with responsible officers as team leader EE to minimum level

of Line Inspectors.

4. On the predefined date and time, all the officers and line staff shall be responsible to report

with required tools, safety appliances, expected line materials etc. Predefined team leader

BEFORE MAINTENANCE AFTER MAINTENANCE

(EE/AE) will take permit to work on the line from original source end and Not to Back

Feed Permit from all the expected substations/points from where back feeding of supply

is possible. Locations of interconnection with other lines through AB Switch/Isolator from

where back feeding is possible, Switches shall be kept open, locked and individual person

shall be deputed with clear instructions regarding not to operate till next instructions.

Special care shall be taken for Permit to work shall be taken from all the feeding ends and

ensure that all the VCBs are OFF, Switches are open and locked, Caution Boards are

affixed. Specific remarks shall be entered in the job-sheet of section incharge of

patrolling team regarding crossing or availability of other lines or on the same support of

the line taken for maintenance to avoid accidents. 33 KV AB or Armored cable may cause

hazardous shock due to statically charge. All the conductors shall be discharged Short

circuited and earthed to ensure the Safety Zone before work execution. Counting of the

persons must be ensured before and after the work execution. After maintenance work

execution, all the line shorting, earthing, and discharge are to be removed before

cancellation of work permit.

5. Predefined team leader (EE/AE) will issue Sub-Permit to work to the other team in-charge

with clear instructions as above, dated signature and time.

6. Concerned team leader shall carryout the maintenance work and submit the patrolling

report on prescribed format. Additional work like Pole straightening/ Pole

replacement/heavy tree cutting/conductor replacement/revetment of land erosion due to

flood or other reasons, re-grouting of Stays etc with help of STC wing/local bodies.

BEFORE MAINTENANCE (TILTED POLE) AFTER MAINTENANCE

7. Team leaders shall be responsible to ensure strict compliance of safety procedures and

rules during maintenance work.

8. Team leaders shall be responsible to ensure strict compliance of standard practices

regarding safe clearance of 33 KV lines from ground level Railway/Road crossing.

Guarding of Railway/Road crossing must be made intact and effectively connected to

earth.

9. Team leaders shall be responsible to ensure that lightening Arrestors are invariably

connected with line and properly earthed at both the ends of overhead/underground cable.

BEFORE MAINTENANCE (TILTED INSULATOR) AFTER MAINTENANCE

4. Maintenance of HT Consumer’s Premises

No any isolation arrangement with AB Switch or Isolator is permitted between the line from

source substation to the Metering CTPT in the premises of HT Consumer.

During the monthly reading or inspection of HT Consumers, Officers of STM/MT/(O&M)

shall be responsible jointly to ensure inspection and maintenance of system as under:-

1. Physical joint inspection of all the seals to be done and compare with the previous record.

If any abnormality is noticed, procedure of panchanama etc. is to be adopted. In absence

of Joint team Officers of STM/MT/(O&M), any single authority shall not be authorized in

any condition to temper/alter any seal or connection of metering system.

2. Ensure intact earth connection with the screening of AB cables and Metering equipments.

3. Ensure intact connections of CTPT unit’s terminals and apply proper insulation.

4. Ensure mechanical intactness of GI Pipe covering of the cable connected between CTPT

Secondary terminal box to Meter Box.

5. Ensure intact connections of lightening Arrestors with cable ends and earth connections.

6. Ensure oil level up to the mark in CTPT Unit and prevent oil leakage.

12

5. Maintenance Of 33/11 Kv Substation

33/11KV substation is a prime part of Power distribution network, for uninterrupted power

supply to distribution areas with possible minimum outages. This is possible only if the

equipments installed at 33/11KV S/s i.e. power transformers and other equipments along with

their protective equipment must be maintained properly to render healthy and fault free services.

Breakdown of such costlier equipments not only threaten the life of such equipment but also

cause outage in supply and therefore financial loss to company. Hence in order to avoid

breakdown of such equipments, preventive maintenance is utmost necessary. Therefore, the staff

posted in 33/11KV S/s is supposed to have sufficient technical know-how in regard to these

equipments for proper operation and maintenance of same. The power transformer is the main

equipment which involved a considerable cost also and therefore installed with a complete

protective system comprising of 33KV vacuum circuit breaker, 11KV vacuum circuit breaker,

33KV & 11KV L.A., 33KV & 11KV current transformer, isolators, AB switch, control panel,

battery and battery charger.

Normally the useful life of power transformer and associated protective equipments is

assessed to 25 years or more depends on the way it is being operated and maintained. The most

prominent cause of failure of power transformer is identified due to overloading and failure of

protective system. Apart from this lack of maintenance is also another cause of failure. Hence it

is necessary to carry out scheduled maintenance of all equipments installed in 33/11KV S/s

regularly as per the maintenance guidelines laid out.

At the 33/11KV S/s the maintenance of power transformer and their protective equipment

is carried out by EE(STM) / AE (TSG) as per maintenance schedule. Maintenance of other part

like isolator, bus, jumpers, battery, earthing and safety appliances is being done by EE(O&M) /

AE(O&M) / JE (O&M) of concerned (O&M) Division.

MPPKVVCL, JABALPUR 13

6. Instructions for operator of 33/11 KV S/s in respect of

various Alarms

S. No. Alarm Indicator Necessary Action

1 Oil Temp. Alarm

Accept the alarm. Note down indication, go to yard and observe

for temperature rise if any, by touching the body of Power

transformer. The reading of winding/oil temperature meter

recorded and inform to EE/AE immediately for abnormality

developed if any.

2 Winding Temp.

Alarm

Accept the alarm. Note down indication, go to yard and observe

for temperature rise if any, by touching the body of Power

transformer. The reading of winding/oil temp. meter recorded and

inform to EE/AE immediately for abnormality developed if any.

3 Buchhloz Alarm

Accept the alarm and then isolate the PTR from load. First of all,

11 KV load should be isolated by hand tripping the 11 KV VCB

followed by 33 KV VCB. Inform to EE/AE immediately

4 Buchhloz Trip

Accept the alarm and then isolate the PTR from load. First of all,

11 KV load should be isolated by hand tripping the 11 KV VCB

followed by 33 KV VCB. Inform to EE/AE immediately

5 Capacitor Bank

Trip Cancelled the alarm, note the relay indication and inform to EE/AE.

6 Feeder Breaker Trip Accept the alarm note down the indication and action to be taken according to operating instruction.

6.1. Buchholz Relay:

The Buchholz Relay operated mainly due to internal fault developed in the Xmer for any

of the following reasons:-

S. No. Alarm may be actuated due to

1. Core bolt insulation failure

2. Core lamination short

3. Internal loose contact

4. Internal local hot point

5. Low oil level due to frequent oil leakage

6. Air trapped inside the Xmer accumulated in relay.


S. No. Tripping may occur due to

1. Two phase short circuit

2. Inter turn short circuit

3. Winding to earth short

4. Puncture of bushing

5. Trip contact short by insects

WORKING OF BUCHHOLZ RELAY


7. Pre-monsoon and post monsoon maintenance and

check list thereof

1. All the gasket joints of Xmer‘s body to be checked and ensure there is no any oil

leakage from any joint.

2. To clean the HV & LV bushing, checked for cracks and replace same immediately if

found defective.

3. Trapped air should be released from all bushings, radiator and Buchholz relay.

4. Buchholz relay, winding and oil temperature alarm/trip should be checked and

ensure the tripping of the Power Xmer tripped from both ends via master trip relay.

5. The oil must be available upto specified level. It has to be confirmed via glass oil level

indicator, by magnetic oil level indicator. However, for physically verification, open

the top cover of conservator and confirm the fill level.

6. The main tank of the Power Xmer must be earthed from two points terminated in

separate earth pits. Connection must be checked for its proper tightness.

7. The silica gel color must be blue and oil in oil cup should be upto the mark.

8. The thermometer pocket should be cleaned and filled with fresh oil.

9. The cleaning of CT and connection of primary and secondary must be checked for

tightness.

10. It has to ensure that CT & PT connection must be terminated through marshalene box

to control panel and star point must be made only at marshalene box which should be

properly tighten and earthed. The box should also be earthed properly.

11. After finishing the assigned job, a check should be made to ensure that no tools,

clothes, any other material is left on Xmer top.

12. The neutral connection tightness must be checked. It should be clamped with proper

size clamps. Both neutral points from the neutral bushing of the transformer should be

connected to separate earth pits.

7.1. Current Transformer:

The current Xmer is provided mainly for metering and protection purpose for which

the current Xmer have two core, one for metering and other for protection. Accuracy class

of both core are different. For protection, CT core should have 5P10 or 10P10 accuracy class

whereas metering side core having 0.5 or 1.0 accuracy class.


7.2. Testing of CT:

IR value of CT must be taken through the 1KV megger. Care should be taken to ensure

that when the secondary to secondary or secondary to earth IR value is measured, the megger

used should have 500 V rating as higher DC voltage may cause core saturation.

Terminal Measured Value

Primary to Earth = MΩ Primary to 1S1 = MΩ Primary to 2S1 = MΩ 1S1 to Earth = MΩ 2S1 to Earth = MΩ 1S1 to 2S1 = MΩ

P is the primary, 1S1 and 2S1 are the terminals of secondary core.

7.3. Polarity Test :

Primary of CT have marked with P1 and P2 for main and load. When DC voltage injected

via cell on primary side with P1 connected to + ve of cell and P2 to negative of cell and

instantly make and break these connections , to see the indication of deflection on voltmeter

on secondary core. It has to ensure that when one core is under testing, the other core must

be shorted.

33KV CT


7.4. Primary Injection:

The primary current is injected on primary P1 and P2 terminal Via loading Xmer and

current is measured in secondary terminal to check the CT ratio error. The permissible limit

of ratio error is ±10%.

S. No. Primary Current onP1-

P2

Measure in Secondary

1S1-1S2

Measure insecondary2S1-

2S2 % error

1 100% 2 50% 3 30% 4 10%

7.5. Control Panel:

It is an indoor equipment installed at control room and earthed in separate earth pit.

Control Panel provided the indication of OFF/ON, Trip Circuit healthy for VCB. The control

panel also equipped with Ammeter, Voltmeter to indicate the instantaneous values of current

and voltage in all the three phases.

During maintenance all cable connections are to be checked for their tightness. All

indications are to be checked. AC and DC supply to be checked. All cable connections should

be terminated as per approved schematic drawing using proper ferruling and coding.


7.6. Relay:

To protect the Power Xmer from over current during normal and fault conditions, the

relay is installed to serve the purpose by sensing the over current/fault current

instantaneously. Normally 2 O/C + 1E/F relays are provided on 11KV side of Power Xmer

and 33 and 11 Kv feeders whereas 3 O/C relays are provided on primary side of Power Xmer.

Testing of relays have to be carried out as per the schedule and all settings i.e. plug setting,

time lever setting, and relay characteristic should be checked and verify according to relay

coordination to avoid the tripping at EHV substation.

7.7. Battery/ Battery Charger:

The 30 Volt DC is required for tripping and indication thereof. All protective equipments

are connected to DC supply from the battery of substation . One battery set comprised of 15

nos. cells each having 2.0-volt rating to provide total 150 AH capacity to battery. The battery

charger should always remain connected with load and battery. During maintenance, each

cell should be cleaned, distilled water should be top-up to marked level, tightness of battery

terminal and connected strips should be checked, and petroleum jelly should be applied

invariably on all joints to avoid sulphation.


7.8. Lightning Arrestor:

The Lightning .Arrestor is provided to protect various substation equipments from

lightning strokes. During maintenance of lightning arrestor, first of all, check is performed

to ensure no puncture or cracks on porcelain insulator. Measure the IR values from terminal

to earth. It to ensure that both of the earth terminal at lightning arrestor should be connected

to separate earth pits specifically meant for it.

7.9. Vacuum Circuit Breaker:

It is the equipment to isolate the supply in Normal and fault condition. During

maintenance, the IR values of all three phases should be taken using 1KV megger. Clean all

porcelain parts with ensuring to jumper intact. More importantly the VCB should be tested

for performing its satisfactory working at 70 and 110% of DC voltage. Meggering should be

done to measure the insulation resistance between terminals as suggested below. It should

be performed for each phase separately.

Terminal Measured Value

Upper Pole to Earth = MΩ

Upper Pole to Lower Pole = MΩ Lower Pole to Earth = MΩ


During maintenance it should be checked that the structure of VCB is earthed properly.

7.10. Metering Equipment:

For energy audit, the metering equipment (CT,PT unit) is installed at each incoming and

outgoing feeders. The primary side of the metering equipment is connected to HV side and

secondary connected to respective CT and PT terminals of energy meter. During

maintenance the IR value of metering equipment should be taken using 1KV megger. If the

consumption is not being recorded correctly, the phase association should be checked along

with ME ratio . Metering equipment should be earthed properly from available two points

and the earth connections should be checked for their tightness.

VACUUM CIRCUIT BREAKER AFTER MAINTENANCE

FAILED ME (SWELLED ME) AFTER MAINTENANCE


7.11. Earthing:

Earthing is provided to clear the fault current due to system disturbances and to keep all

equipments at same voltage in the event of the fault condition. All the equipments of

substation should be properly earthed and connected to earth mesh and earth pit. The earth

resistance of substation and each earth pit must be taken once in a year by earth tester. The

earth resistance must be below to 1.0-ohm else necessary arrangements should made to

improve same.


8. Maintenance Power Transformer

8.1. Power Transformer Maintenance Schedule

S. No. Work Time

Cycle

Responsible

Officer

1 Checking of breather of power transformer to observe the color of

silica gel. If it turned from Blue to Pink replaced and reconditioned. Daily

Operator of

33/11KV S/s

2

The oil level indicator on Power X-mar indicates the level of oil in

conservator tank. Level to be checked daily. Same to be recorded in

log book of sub-station.

Daily Operator of

33/11KV S/s

3

The physical observation for tightness of clamps connection, joints or

red-hot points and any abnormal sound produced by Power X-mar &

other equipments. To be checked daily and recorded in log book of

sub-station.

Daily Operator of

33/11KV S/s

4.

Two temperature meters are provided in Power Xmer for observing

winding and oil temperatures each. The hourly reading of both temp.

meter is taken and recorded in log book of S/s.

Hourly Operator of

33/11KV S/s

5

The physical observation of explosion vent of power Xmer from

ground to ensure no oil leakages or cracks developed in diaphragm.

Recorded same in log book of S/s.

Daily Operator of

33/11KV S/s

6

The maintenance of battery by cleaning, pouring the distilled water

upto specified level and reading of pilot cell voltages specific gravity.

To be checked daily and recorded in log book of sub-station.

Daily Operator of

33/11KV S/s

7 After taking shut down on power Xmer, the explosion vent, pipe and

diaphragm are to be physically checked for their healthy condition. Quarterly

EE STM/AE

TSG

8

The IR value of Power Xmer (by 5KV/1 KV Megger) from HV to

earth, LV to earth and HV to LV after disconnecting the neutral from

earth. The measured IR values at the ambient temperature should be

converted at 60o C and then compare same with the initial

commissioning results and records should be maintained. (Action

required for reconditioning if results appeared to go beyond safe

value)

Quarterly EE STM/AE

TSG

9 The silica gel breather unit completely detached from Power Xmer Quarterly EE STM/AE


S. No. Work Time

Cycle

Responsible

Officer

for cleaning and filling with fresh silica gel and oil upto specified

level in oil cup.

TSG

10

The alarm and trip contact of winding temp. and oil temp. meters

shorted to check the tripping of VCB from both ends. (Prior to test

VCB should be kept in ON position).

Quarterly EE STM/AE

TSG

11

Oil samples of Power Xmer drain out from sample valve and

properly collected in container and tested at oil testing laboratory

(MTRU) for moisture content, BDV, tan ∂ and resistivity. Test result

should be compared with the specified values to take further actions

accordingly.

Quarterly EE STM/AE

TSG

12

Main Buchholz relay and OLTC Buchholz relay alarm and trip

contacts are to be checked for alarm and tripping of VCB. (By short

circuited contacts physically)

Quarterly EE STM/AE

TSG

13

For testing of mercury switch provided in Buchholz Relay, both the

valves provided at conservator and main tank side are kept closed.

Now oil is drained out directly from Buchholz Relay by opening its

bottom nut. As the air to go inside, first float makes contacts of

mercury switch to actuate the alarm followed by actuation of trip

contact of other mercury switch

Quarterly EE STM/AE

TSG

14

Checking of tightness of the jumpers at HV and LV bushings and of

neutral connection at neutral terminals and earthing point. The IR

values of all protective equipments.

Quarterly EE STM/AE

TSG

15 The calibration of winding temp. Meter/oil temp. meter by standard

thermometer. Quarterly

EE STM/AE

TSG

16

The magnitude of exciting current of the power transformer should

be measured at the time of maintenance and compared same with the

initial values. Higher value of exciting current indicates the

possibility of internal leakage or short circuit between winding

layers.

Quarterly EE STM/AE

TSG

17 The resistance of HV side winding and LV side winding must be

recorded during maintenance and maintain the record.

Quarterly

EE STM/AE

TSG

18 The thermometer pocket provided on Xmer main tank. Get it cleaned

and top-up with fresh Xmer oil. Quarterly

EE STM/AE

TSG

19 The inspection of core and winding to be done if it is very essential.

As per

Requirem

ent

EE STM/AE

TSG

20

The IR values of lightening arrestor installed at both sides of PTR to

be taken and maintained the record. The arrestor must be changed for

any chipping observed in insulator. The earthings of LA to be

Quarterly EE STM/AE

TSG


S. No. Work Time

Cycle

Responsible

Officer

checked physically for their tightness.

21

The control panel of substation should be inspected thoroughly for

tightness of wiring, annunciation, ON/OF indication, supply of DC

and AC at control panels. The fuses on both circuit to be checked for

proper sizes. The setting of relays i.e. O/C relay and E/F relay, over

voltage relay should be carried out along with alarm annunciation

and tripping. The % setting of O/C and E/F relay and time lever

setting with the operating characteristics as per relay coordination

should be checked and maintain the record.

Quarterly EE STM/AE

TSG

22

The testing of relay for their healthy operation and characteristics

should be performed by relay testing kit and actual time of fault

clearance by injecting the current should be checked to ensure

coordination with EHV substation.

Quarterly EE STM/AE

TSG

23

Maintenance of battery set should be done to ensure proper DC

voltage, specific gravity, tightness of strips and cleaning of

connecting strips. Petroleum jelly should be applied to avoid the

sulphation. During once in year, the operation of float charging/Boost

charging should be checked for the healthiness of battery charger.

Quarterly EE STM/AE

TSG

24

A number of earth pits are provided in 33/11KV S/s. for proper

clearance fault current during system instability keeping the

operating staff safe. The earth resistance of all earth pit should be

measured by earth tester and value to be recorded and maintained. It

is preferable to take the earth resistance in the month of May/June.

Quarterly EE STM/AE

TSG

BEFORE MAINTENANCE (RED SILICA GEL) AFTER MAINTENANCE (BLUE SILICA GEL)


9. Operation and Maintenance of 11 kV 600 KVAR

Capacitor Bank

1. Before putting the Capacitor Bank in service, the earth switch must be opened to

isolate same from earth and then only the main isolator contacts should be closed.

Further it should be ensuring that all male/female contacts of all phases of isolator

should get arrested in each other properly.

2. During the operation of isolator or electrical equipment, the hand gloves must be used

by the operator.

3. 600 KVAR bank equipped with an automatic vacuum switch which operates

automatically producing a prominent sound when the load current become more than

52 Amp.

4. After every tripping, the automatic switch of Capacitor Bank takes 10 minutes time

interval. Thereafter the it brings the capacitor bank back to normal service only when

the current valued more than 52 Amps. The automatic switch keeps the capacitor bank

in service for a system voltage ranging only between 9 KV to 12 KV. Beyond this

values the automatic switch will remain Off.

5. For maintenance or replacement of fuse of Capacitor unit, supply should be tripped

from Xmer main VCB. Then the bank isolator should be opened, and earth switch

closed and after discharging of all three phases, the maintenance work should be

carried out.

Note:- While attempting the megger on the Capacitor unit, both bushing terminals must be

shorted by a link and then only values should be taken.


10. Operation and Maintenance of 11 kV 1200 KVAr

Capacitor Bank

1. Ensure that the control panel of Capacitor VCB is healthy and getting rated DC

voltage.

2. Before charging of capacitor bank, trip test of VCB (associated with capacitor bank)

must be carried out via relays for satisfactory working of VCB.

3. Before putting the Capacitor Bank in service, the earth switch must be opened to

isolate same from earth and then only the main isolator contacts should be closed.

Further it should be ensuring that all male/female contacts of all phases of isolator

should get arrested in each other properly

4. Before putting the VCB in service it should be checked that the trip circuit should be

healthy and other relays must be reset. It must be ensuring that the load on Xmer is

more than 100 Amps and then only the VCB should be put ON from control Room.

5. In the event of any circuit fault in Capacitor Bank or main supply goes off, the Bank

VCB should trip immediately. After restoration of power supply, further action should

be taken as per point 4 above.

6. For maintenance or replacement of fuse of Capacitor unit, supply should be tripped

from Xmer main VCB. Then the bank isolator should be opened, and earth switch

closed and after discharging of all three phases, the maintenance work should be

carried out.

7. If Capacitor Bank tripped on O/C or E/F indication or on unbalanced voltage, operator

should immediate inform same to EE(STM)/AE (TSG).

Note:- While attempting the megger on the Capacitor unit, both bushing terminals must be

shorted by a link and then only values should be taken


11. Reconditioning of Power Transformer

During service, Power Xmer always keep energized. Due to temperature variation and

presence of moisture content in the environment, the insulation values get deteriorated

continuously. Beyond permissible limits of such deterioration, such transformers required

immediate reconditioning to avoid premature complete failure. Reconditioning enhance the

service life of Xmer. IR values in respect of every Power Xmer must be taken quarterly and

recorded. Such arrived values are converted at 60oC. If the converted IR value is observed

below 75 MΩ (between HV – E) and break down voltage of oil is observed below 30 KV it

is a clear indication that the Xmer required reconditioning. The conversion chart is enclosed

in Annexure-3. At present Company has given the rate contract award to different repairers

for reconditioning of Xmer. Such Xmer are allotted to repairers by regional CE’s and the

process is being monitored by CGM (O&M) at corporate office.

11.1. Procedure:

1. Power Xmer’s having poor IR value and required reconditioning are enlisted and

submitted to higher offices. Regional CE allotted same to repairs as per the merit.

2. If load on a particular transformer proposed for reconditioning, is not managed by the

neighboring transformer in same substation, a separate transformer of suitable

capacity should be installed to take the load of the relieved transformer.

3. The proposed Power Xmer seeking reconditioning, should be returned to Area Store

safely by EE(O&M)/EE(STM). In Area Store the repairer or its representative along

with EE(STM) make a joint testing. Further action for reconditioning is taken by

regional Chief Engineer office adhering to prevailing rate contact award. After

reconditioning. the Xmer returned by repairers to area store.


12. Procedure for replacement / repairing of failed

Power Transformer

On reporting of any abnormality developed in existing Power Xmer, the concerned

EE(STM) after performing necessary tests as required and as per his findings, may declared

same as failed followed by sending saving ram to this effect. Here it has to be confirmed

whether the said transformer has got failed within or beyond the guarantee period. If the

Xmer failed within guarantee period of supply or repair, it should be informed immediately

to CE (Pur.) along with concerned manufacture/repairer with testing results so that action

may be taken accordingly as per prevailing purchase order/rate contact whichever is

applicable.

If the Xmer failed beyond guarantee period, it should be informed immediately to

higher officer and supply should be managed from other transformer on priority.

EE(STM)/EE(O&M) after carrying out a joint inspection and testing, submitted a PRDR

(Performa Report and Detailed report) to higher officer indicating all possible technical

reasons responsible for such failure. After the failed Xmer is returned to Area Store, the

CE(Stores) has allotted same to repairer as per the rate contact award. After the allotment,

the further action such as joint inspection, store inspection, allotment of oil, and final

inspection are arranged by regional CE office. The formats of PR/DR are enclosed is

enclosed as Annexure-4.


APPENDIX-1

Sub:-Commissioning report of Power Xmer/ NEW/ Repair/

Reconditioned/Augmentation/Additional.

Sr. No History & Details of Power X-mer

1 Name of 33/11KV S/s

2 Name of Circle

3 Name of (O&M) Dn.

4 Power Xmer Commissioned (Aug/Addl./After repair/ Reconditioned

5 Name of Manufacturer/Repairer

6 Sr. No. of Xmer

7 Name of Repair / Sr. no. & date of Repair

8 Capacity of Xmer

9(a) Voltage of Xmer 33KV Side

9(b) Voltage of Xmer 11KV Side

10 % impedance of Xmer

11 No. of Taps

12 Transformer commissioned at Tap no.

13 P.O. No. of Xmer/ RCA Award no. of Repairers

14 Power Xmer receive from Area store/ Repairer

15 Gate pass nos. Date

16 Xmer commissioned against STN work (Aug/Addl./Failure)

17 Details of Old Xmer

17(a) Make of Transformer

17(b) Sr. No. of Transformer

17(c) Name of Manufacturer

17(d) Capacity of Xmer

17(e) Xmer proposed to be Commissioned at 33/11KV S/s or returned to area

(Date) Store

EE (O&M) EE (STM)

M.P.P.K.V.V.C.L.__________ M.P.P.K.V.V.C.L.__________


1. Date of Commissioning ------------------------------------------

2. Name of 33/11 KV S/s ------------------------------------------

3. Name of Manufacture/ Repairer ------------------------------------------

4. Sr. No. of Xmer ------------------------------------------

5. % Impedance of Xmer ------------------------------------------

1. IR Value of Power X-mer :-

VALUE IN 15 SECOND VALUE IN 60 SECOND

Winding IR Value (MΩ) Winding IR Value (MΩ)

HV – E HV – E

LV – E LV – E

HV - LV HV - LV

2. Winding Resistance of HV side & LV side of Power X-mer :-

HV Winding Resistance LV Winding Resistance LV Winding to Neutral

Resistance

Winding Value (Ω) Winding Value (Ω Winding Value (Ω

RY ry rn

YB yb yn

BR br bn

3. Voltage Ratio Test :-

Tap no. RY

(Volt.)

YB

(Volt.)

BR

(Volt.)

ry

(Volt.)

yb

(volt.)

br

(Volt.)

rn

(Volt.)

yn

(Volt.)

bn

(Volt.)

1

2

3

4

5

6

4. Magnetizing current HV open circuited /LV open circuited :-

Phase (HV open

circuited)

Current (mA) Tap No.(2) Phase (LV open

circuited)

Current (mA) Tap No.(2)

R r

Y y

B b

5. Magnetic Balance test :-


Tap No.

Phase

out

Phase to Phase HV Side

(Volt)

Phase to Phase LV Side

(Volt)

LV Side to Neutral (Volt)

RY YB BR ry yb br rn yn bn

02 B

02 R

02 Y

6. Vector Group Test:-

0.4KV (LT) Supply given on HV side.

HV Side R phase and LV side R phase is short circuited.

RY = Rn + Yn

Rb = Ry

By > Bb

7. Short Circuit Test:- 0.4 KV (LT) supply on HV side given and LV side of the Transformer is Short

circuited with neutral.

Remarks of Testing Results :-

EE (O&M) EE (STM)


Phase Voltage (Volt) Phase Voltage (Volt) Phase Voltage (Volt)

RY Rn Rb

YB Yn Bb

BR Ry By

Phase Current (Amp) Phase Current (Amp) Neutral Current (Amp)

R r n

Y y

B b

R

n

B

b

y

Y


Protection check before energizing of Power Transformer

1 All radiator valves bottom/Top opened

2 Oil filled up to filled level

3 Air release from Buchhloz & Top cover and Bushing of

HV & LV

4 Buchholz alarm/Trip test check by injecting Air or

drainage of oil from Buchholz (Both side valve closed)

5 Equalizer pipe of conservator/Explosion vent open

6 Silica Breather fitted / Oil filled in oil cup, up Mark level

7 Any leakage observed /tank / Bushing/ Radiator/Valve

8 Trip test from both side taken through the over

current/earth fault relay

9 Setting provided on relay 33KV/11KV side Over current relay

(a) Plug setting

(b) Time lever Setting

Earth Fault relay

(c) Plug setting

(d) Time lever Setting

10 CT ratio of 33KV side & 11KV side (CT ratio required to

be changed because of higher capacity Xmer Augmented

if yes Requirement )

33KV Side

11KV Side

11 Transformer Charged on dated

12 Load on Xmer taken at

Remark

EE (O&M) EE (STM)



Appendix-2

Name of Circle: _________________ Name of STM Div.: ______________

1 Name of Executive Engineer (O&M)

2 Name of Executive Engineer (STM)

3 [A] Name of 33/11KV S/s where Xmer failed

[B] Date & time of failure

4 Specification of Equipment

Capacity

Volt. Ratio

Make

Sr. No.

Mfg. Year

5 [A] Purchase Order No.& Dt.

[B] Xmer failed in WGP/BGP

[C] If WGP name of supplier/ Repairer/ Reconditioner

6 Date of commissioning

7 Was the equipment new when installed at place where it failed

8 Date of last maintenance prior to failure of the equipment the following

result. (enclosed)

9 [A] I.R. value after breakdown, continuity between phases.

[B] Oil level.

[C] Condition of silica gel.

[D] BDV of oil with 2.5mm gap

10 Whether conditions at the time of failure.

[A] Resistance of earthing.

[B] Particulars of earthing.

11 [A] Whether lightening arrestor provided

[B] Whether lightening arrestor connections were tightened

[C]Type & rating of Lightening Arrestor.

[D] Earth resistance of LA earth Pit.

12 [A] Type of protective devices used on HV side.


[B] Rating and setting of protective device such as fuses OCB/VCB etc.

on the date of break down

14 The protective device operated on the LV/HV side. (Details of Setting

with CT Ratio)

15 Peak load recorded -Average load (in Amp)

16 Whether the transformer was repaired, name of repairer

17 Operation carried out for detection of failure.

(Test result enclosed)

18 Probable cause of break down

19 Details of damages (core inspection)

20 Restoration of supply.


Appendix -2(b)

Detail Report of Power Transformer Failure

Name of Circle:____________ Name of STM Div.:_______________

[I] DETAIL REPORT

[A] MAKE

[B] S. No. of Transformer

[C] Capacity

[D] Voltage Ratio

[E] Order against which purchase

[F] Whether New / Repaired

[G] Whether it was installed previously also at other place / places for

which it remained in service to be also stated.

[H] If repaired details of earlier failed and repaired which date be given

[I] Time taken for repair / replacement of unit and its responsibility

[J] Remedial measures taken / proposed to be taken for stoppage of such

failure in future

[K] Action taken to repair the unit

[L] Date of failure of Transformer previously at the same place.

[II]

[A] Date of installation

[B] Arrangement of Earthing and value of earth resistance.

[C]

Whether the Lightening Arrester was provided. Condition of

Lightening Arrester after failure be stated along with the

resistance at Lightening Arrester.

[D] Condition of breather silica gel & oil level.

[E] Details of Protection on primary and Secondary sides and

sizes of fuses on HV/LV side of transformer.


[III] MAINTENANCE

[A] Maintenance with dates I.R. value and oil test results.

[B] Details of I.R. value

[C] A copy of maintenance of Xmer carried out prior to failure

(enclosed)

[IV] How the failure was detected

[V] Extent of damage

[VI] Reason of failure

[VII] Responsibility

[VIII] Restoration of supply

EE(O&M) EE(STM)

M.P.P.K.V.V.C.L M.P.P.K.V.V.C.L


Appendix-3

Minimum IR Value required at different Temperature Corresponding to 75 M-ohm at 60°C

Sr. No. Temperature (°C) IR Value in M-0hm MF for 60°C

1 20 852 0.088

2 21 798 0.094

3 22 750 0.1

4 23 694 0.108

5 24 647 0.116

6 25 600 0.125

7 26 568 0.132

8 27 543 0.138

9 28 521 0.144

10 29 493 0.152

11 30 469 0.16

12 31 431 0.174

13 32 417 0.18

14 33 395 0.19

15 34 375 0.2

16 35 341 0.22

17 36 313 0.24

18 37 294 0.255

19 38 278 0.27

20 39 263 0.285

21 40 250 0.3

22 41 234 0.32

23 42 221 0.34

24 43 208 0.36

25 44 197 0.38

26 45 188 0.4

27 46 174 0.43

28 47 167 0.45

29 48 153 0.49

30 49 142 0.53

31 50 134 0.56

32 51 129 0.58

33 52 120 0.625

34 53 114 0.66


35 54 107 0.7

36 55 101 0.74

37 56 96 0.78

38 57 91 0.825

39 58 85 0.88

40 59 79 0.95

41 60 75 1

42 61 68 1.1

43 62 63 1.2

Relay Setting

Characteristics → 3 1.3 0.65 1.5

PSM↓ t t t t

Time in Seconds

1.1 73.37 32.94 380.95 135.00

1.2 38.32 17.19 181.82 67.50

1.3 26.61 11.92 115.94 45.00

1.4 20.73 9.28 83.33 33.75

1.5 17.19 7.69 64.00 27.00

1.6 14.82 6.62 51.28 22.50

1.7 13.12 5.86 42.33 19.29

1.8 11.84 5.28 35.71 16.88

1.9 10.84 4.83 30.65 15.00

2 10.03 4.47 26.67 13.50

2.5 7.57 3.36 15.24 9.00

3 6.30 2.79 10.00 6.75

3.5 5.52 2.44 7.11 5.40

4 4.98 2.20 5.33 4.50

4.5 4.58 2.02 4.16 3.86

5 4.28 1.89 3.33 3.38

5.5 4.04 1.78 2.74 3.00

6 3.84 1.69 2.29 2.70

6.5 3.67 1.61 1.94 2.45

7 3.53 1.55 1.67 2.25

7.5 3.40 1.49 1.45 2.08

8 3.30 1.44 1.27 1.93

8.5 3.20 1.40 1.12 1.80


Characteristics → 3 1.3 0.65 1.5

PSM↓ t t t t

Time in Seconds

9 3.12 1.36 1.00 1.69

9.5 3.04 1.33 0.90 1.59

10 2.97 1.30 0.81 1.50

10.5 2.91 1.27 0.73 1.42

11 2.85 1.24 0.67 1.35

11.5 2.80 1.22 0.61 1.29

12 2.75 1.20 0.56 1.23

12.5 2.70 1.18 0.52 1.17

13 2.66 1.16 0.48 1.13

13.5 2.62 1.14 0.44 1.08

14 2.58 1.12 0.41 1.04

14.5 2.55 1.11 0.38 1.00

15 2.52 1.09 0.36 0.96

15.5 2.48 1.08 0.33 0.93

16 2.46 1.07 0.31 0.90

16.5 2.43 1.05 0.29 0.87

17 2.40 1.04 0.28 0.84

17.5 2.38 1.03 0.26 0.82

18 2.35 1.02 0.25 0.79

18.5 2.33 1.01 0.23 0.77

19 2.31 1.00 0.22 0.75

19.5 2.29 0.99 0.21 0.73

20 2.27 0.98 0.20 0.71


13. Maintenance Of 11kV Primary Distribution

System:-

The responsibility of 11KV primary distribution system maintenance in urban area

shall be of Executive Engineer(City) and Assistant Engineer(HT-Maintenance). In rural area

the Assistant Engineer of Sub-Division and D/c Incharge shall be responsible.

13.1. Preventive Maintenance:

Pre-monsoon and Post-monsoon maintenance to be carried out looking to the possible

break down during monsoon. Replacement of weak insulator / resagging of conductor /

binding, guarding, condition of pole, clearance of conductor from ground / trees as per

standard to be essentially maintained so that undesirable break down and accidents could be

avoided under this:-

1. Executive Engineer of the area along with sub-ordinate engineers, line staff and with

the help of local authority shall finalize the programme of tree cutting and other

essential works to be carried out.

2. As per the programme of maintenance the HT consumers connected through the 11KV

line and other effected consumers shall be informed about the interruption in power

supply (Shut Down Notice) at least 48 hours before through the Media / Newspaper

etc.

3. As per the programme of maintenance all officers and staff shall reach to the pre-

decided site spot with tools, security appliances and probable required line material.

The Officer Incharge (EE/AE) invariably shall obtain the permit to work from the

source ends of 11KV line and from the possible feedback source ends for Not to Back

Feed permit. Any possible feedback point such as interconnection with other 11 KV

line through AB switch/ isolator shall be locked and an attendant shall be deputed

separately at such place with the clear instructions that until the authorized person

directs him till, he should be on duty there to ensure that no any operation can be done

by anybody. After obtaining the permit to work from all possible sources, it must be

ensured that all VCBs are in off position and all three phases of Isolator / AB Switch

are open. The Sign Board of “CAUTION” tagged on these equipments. The possibility

of feedback from 11KV line of HT consumer installation shall be specially kept in

mind. On the job sheet provided to the patrolling gang should have the information

of other crossing lines, other lines erected on the same poles and guidelines for

protection to avoid any possible accident. The 11KV line being on cable and use of

capacitor on HT installation may create charge hence all conductors shall be


discharged short circuited and earthed. In urban area 11KV and LT composite lines,

LT lines/street light line may get the power supply from other alternate source, so

special precaution to be taken while working on such lines. The complete patrolling

network should be earthed at all possible points, establishment of Safety Zone must

be ensured. After completion of the work it will be necessary to remove all short-

circuiting wires, Discharge rods and earthings. Before commencement of work and

after completion of work before cancellation of permit, the presence of all officers and

staff should be verified physically and ensured.

4. Each patrolling gang shall have Team leader of rank Assistant Engineer or atleast Line

Inspector to work on separate section of line.

5. The patrolling gang shall submit the patrolling report in the enclosed format. If

additional work of pole straightening / pole replacement / cutting of large branches of

tree / conductor replacement or filling of earth due to rain /flood cuts for stay is

required, then the help of concerned STC Division / local body should be obtained to

complete the work.

6. Incharge of patrolling gang shall ensure to compliance all safety rules / instructions

by working staff during work execution.

7. The clearance of 11KV line from ground shall be ensured as per the Electricity Rules

on Road Crossing or Railway Crossing spans Mesh Guarding / Guarding should be

intact and properly and strongly connected to earth.

8. The lightening arrestor on both ends of the underground / overhead 11KV line to be

properly connected with line, Cable’s screening and lightening arrestor must be

strongly earthed. Keep both the cables (Main and standby cables) always connected

in parallel and charged.


14. Maintenance of 11/0.4 kv Distribution Transformer

The Assistant Engineer (LT) in urban area, and AE (Sub-Division) with D/c. In-

charge shall finalize the maintenance programme, as per the information gathered from line

staff for the required maintenance. Pre-monsoon and Post-monsoon maintenance of

distribution transformers is essential. The concerned Executive Engineer shall be responsible

for cent percent maintenance of all transformers within stipulated time.

In urban area generally, AB switch is provided on the 11KV side in the transformer

DPs. If AB switch is not on 11KV side or is not at a safe clearance from 11KV line, then the

maintenance of transformer should be done after obtaining proper permit. In urban area due

to composite line, the possibility of feedback supply and it’s stepping up can cause fatal

accident. Due to use of inverter / generator in the houses with common neutral connection

remains there making the possibility of feedback on transformer. So, before commencement

of transformer maintenance it should be ensured that from LT side also isolated from all the

switch / MCCB, circuit fuse is open and Safety Zone has been established, then only with

strictly observing safety rules and with prescribed tools the maintenance should be carried

out:-

The main features of transformer maintenance are as follows-

1. Check the breather, if it is not there then providing the same. If not available, plug the

breather pipe and seal it so that moisture may not enter. Provide the new breather as

early as possible.

2. Check the color of breather gel, it should be blue, if not, recondition by heating or

replace by new silica gel.

3. Check that the transformer oil is filled up upto the mark in the bottom cup provided

on the lower side of breather, if not, fill up the transformer oil. The breath whole is

provided on the bottom of breather which is generally plugged by the tape, if so, then

remove the tape.

4. Ensure that the conservator tank of transformer is filled with oil upto the mark, if not

then fill the same.

5. Check the oil leakage, if any, close the valve, tighten the nuts, if the oil leakage is

through bushing then check the rubber cone, replace and tighten it.

6. Check that the conductor / cable connections with is intact with HV and LV stud.

Aluminum lugs or bimetallic clamp of proper size should be used. Temporary winding

should not be used on transformer studs.


7. Check the earthing wires ensure they are not broken /loose /rusted. Clean the neutral

earth connections of transformer and LT line also ensure intact connection.

8. Ensure that the transformer body is properly earthed from two separate places.

Earthing wire of neutral point to be kept at a safe distance to avoid the damage to the

radiator by friction or sparking.

9. Pipe earthing should be in a proper place of damp/moisture containing land, with three

pits in a triangular manner at a distance of 6.5 Mtr. each. Two pits should be on either

side of DP and one in front of DP. Pit should be 2.7 Mtr. deep in which 40 mm. GI

pipe/Earth rod to be inserted upto a depth of 2.5 Mtr. It is always better to make the

earthing on wet land near a water source. To connect the transformer body, neutral

and LA, 6 SWG GI wire to be used.

10. Ensure that the Lightening Arrestors are provided on each phase, if not then arrange,

atleast Y phase must have the Lightening Arrestor .

11. DO fuse should be used in 11 KV side of DTRs of proper size. The size of DO fuse

should be used as given below:-

SN Capacity of Transformer

(KVA ) Use of following capacity of DO

fuse in 11KV ( in Amp.) 1 16 1.0 2 25 1.5 3 50 2.5 4 63 3 5 100 5 6 150 / 160 7.5 7 200 10 8 300 / 315 15 9 500 25

12. If the transformer is not provided with distribution box, then atleast cut-out or Robust

fuse unit must be provided.

13. The end of the LT line cable should be turned down keeping its end towards ground

so that rain water may not enter in the cable to avoid the damage.

14. The earthing of Lightening Arrestor installed on transformer should be done with 6

SWG GI wire by connecting two separate electrodes. The connectivity must be

checked during each maintenance and repaired or replaced. In the new type of LAs

the earth connector is separately provided which ruptures on lightening stroke. If earth

connector found ruptured, instantly connect the earth wire directly with the earth side

stud of the LA and provide new earth connector as soon as possible.

15. On the transformers of 63KVA and above, where 3.5 core PVC cable has been


provided should be replaced with single core XLPE cable on LT side from transformer

bushing to pole fuse unit (Robust pole fuse unit) / distribution box. The size of cable

to be used is as given below:-

SN Capacity of

Transformer (KVA) Use of cable size from LT bushing of transformer to

pole fuse unit 1 16 16 mm sq. 4 core armored PVC cable 2 25 25 mm sq. 4 core armored PVC cable 3 63 70 mm sq. single core LT XLPE

4 100 / 150 / 160 150 mm sq. single core LT XLPE in 3 phase and 70 mm. sq. in neutral

5 200 185 mm sq. LT XLPE in 3 phase and 150 mm sq. in neutral

6 300 / 315 300mm sq. LT XLPE in 3 phase and 150 mm sq. in neutral

7 500 2x300 mm sq. LT XLPE in 3 phase and 1x300 mm sq. in neutral

16. The size of the fuse unit on LT side is depending on the transformer capacity and

maximum load should be used as given below:-

S. No. Capacity of Transformer (KVA) TC Fuse size (SWG)

1 From 16 to 25 22 2 From 50 to 63 16 3 100 14 4 150 / 160 14x2 5 200 18x3 6 300 / 315 14x3

17. The maximum load should be checked by tong tester (clamp on tester) or by MRI data

of meter and accordingly the LT circuit fuse to be provided. Load distribution should

be carried out regularly to balance the load on all three phases and to minimize the

neutral current. Depending on the maximum current recorded, the TC fuse wire size

to be used should be as follows:

S. No. Load on circuit (Amp.) Size of TC Fuse Wire (SWG)

1 20 1x22 2 40 1x18 3 60 1x16 4 80 1x14 5 100 1X12 6 200 2X16


7 160 2X14 8 200 2X12

18. Regular maintenance of LT line should be ensured. The distance of trees / building /

other objects, ground clearance, distance of phase wire and neutral wires should be

maintained. The connection of LT AB cable should be strengthened and insulated.

The boxes mounted on pole should be closed so that birds’ nests, lizard could not enter

in the box to avoid the short circuiting.

19. The LT separators of bamboo or PVC should be provided atleast upto 3 spans from

the transformers DP to avoid the short circuiting. This is also important to prevent the

transformer failure.

20. Proper size of fuse must be available with each line men in urban area and nearby

households in the rural area. Importance of providing proper fuse size should be

enamored to the consumers. Standard size of DO and TC fuse should be provided on

each and every transformer. The SE/EE must ensure the compliance of these

directives. If aluminum wire has been binded by the villagers, then it should be

removed every time and proper size fuse should be provided. If required, the height of

pole fuse unit may be increased.

21. The main reason of transformer failure is over loading so JE/AE should check the

maximum load by clamp on tester or MRI data regularly and accordingly the work of

capacity augmentation of transformers should be taken on priority to avoid the

overloading and to prevent the transformer failure. The tangible proposal for capacity

enhancement (Addl. or Aug.) should be submitted for load management as per the

directives.


15. Maintenance of LT Distribution System

Majority of consumers are connected with LT distribution system. Maximum line loss

occurs in LT distribution system due to loosen connections, leakage with tree, hooking, short

circuiting of conductors/cables, Conductor snapping, etc. These faults are reflecting in failure

of distribution transformers. Hence, maintenance of LT System is almost necessary to ensure

quality and continuity of supply to the consumers.

In consideration of above, LT Distribution system are being modified as under:-

1. Bare conductor LT line is being replaced by A.B. Cables.

2. Ends of A.B. Cables are making insulated to avoid unauthorized connections.

3. Armored cable is using for service cables of the consumers.

4. A.B. Cables to service cables are being connected through pole mounted insulated LT

Box equipped with spring loaded connectors for secured connection and covered to avoid

unwanted connections,

Distribution center In-charge and Assistant Engineer/Junior Engineer in City area

shall be responsible to carry out the LT system maintenance as under:-

1. City area is having LT system in composite line, EE, AE LT Maintenance and AE HT

Maintenance with JEs shall co-ordinate and decide program before monsoon and after

monsoon for maintenance of DTRs and LT system along with11 KV lines on same

supports. Similarly, in rural area, AE Subdivision and Distribution center In-charge shall

decide program for DTRs and LT system along with 11 KV lines of the area so that

during common shut down period maintenance of DTRs and LT system can be

completed with 11 KV lines also. Main points of maintenance to be carried out are as

under:-

S. No.

Equipment or

material for

inspection.

Points of inspection Steps for maintenance

1 2 3 4

1. Pole

Breakage in PCC Pole/ land

erosion due to flood or other

reasons/Pole weak for load

bearing of line etc.

Brocken PCC pole/Rotten

Tubular/RS Joist/Rail/H- Beam

poles may be replaced.

Inclined/bend poles due to over

tension or looseness of line or

Base of inclined pole may be dig

out and refill with boulders or


S. No.

Equipment or

material for

inspection.


stay. concrete. Tension of stay or line

may be corrected.

Unauthorized encroachment near

pole/unsafe clearance from

line/pole/ other wires strung

from pole.

Pole may be shifted under

deposit scheme in safe

location.

Pole in accident prone location

with vehicles or animals.

Pole may be shifted under deposit scheme in safe location or surrounded by fencing.

Pole’s foundation found eroded

or loose or damaged

Restrengthening of pole’s foundation may be done

Pole’s muffing or base

damaged.

Repair the pole muffing with slop for rain water to outside.

Steel pole found rusted.

Paint the Steel Pole arm structure

with Red Oxide paint and

Aluminum Paint.

2. Stay set

Direction of stay is wrong or

correct

Provide new stay incorrect

direction.

Stay loose/damaged. Re-tight loose stay replace

damaged stay

Whether stay insulators are

broken or OK.

Replace broken stay

insulators

Whether earth connection with

stay wire is correct

Ensure intact connection with

stay wire and earth. Wrap

barbed wire if necessary, to

avoid damages by

cow/buffalo/animals

3. LT Cross arm and

steel fittings

Cross arm/clamps/Bracing are

intact in correct passion or slided

Brocken/damaged/inclined

cross arms may be replaced. Re-

fix the cross arms/

bracings/clamps in Correct

position.

Cross arm/clamp slided due to less or over tension of line

Re-fix the cross arms/

bracings/clamps in Correct position

Cross arm/clamps are rusted or

found weak

Replace the rusted or

damaged clamps

Nut Bolts of cross arm

/Bracing found loose Tight the loose Nut Bolts


S. No.

Equipment or

material for

inspection.


4. Insulators and

Hardware

Brocken or damaged insulators Replace broken or damaged

insulators

Insulator loose or rotating Tighten the insulator

Dust/salt or any foreign

material found on insulators Clean the insulators

Insulator’s hardware found

weak or rusted. Replace hardware

5. Conductor and

Earth Wire

Conductor properly strung and

binding with insulator is intact or

not

Tighten loose binding, replace

burnt or damaged bindings.

Neutral conductor and earth

wires connected properly.

Clean rust etc. and reconnect

earth wire with neutral

conductor properly

Clearance from buildings /trees

or other conductors.

If clearance is unsafe and

inadequate, issue notice and shift

line in deposit scheme. Remedial

measures may be taken for safe

clearance from trees

Clearance from earth wire and

phase wire are as per standard

or not.

Ensure proper clearance

Clearance from phase wire and

other line /telephone line are as

per standard or not


Jumpers and joints are intact or

not

Ensure intact joints and

replace jumpers

Strands of conductor found damaged

Repair conductor strands or

replace if required.

Mid span joint or jointing sleeve

damaged

Repair conductor joints or replace

if required

6. Jumper and line

accessories

Jumpers intact with PG

Clamps at both ends or not. Replace PG Clamps and jumpers.

Jumpers of all phase are in safe

clearance or not

Ensure proper clearance between jumpers

Clearance of jumpers from

steel sections/stay are in safe

position or not


between jumpers and steel

sections or stay

Jumpers covered with PVC

insulation or bare

Replace with proper size of

jumpers if required as per


S. No.

Equipment or

material for

inspection.


load

Hot jumpers or burnt

Replace with proper size of

jumpers if required as per

load and tighten properly

PG Clamps loose or hot Tighten PG Clamp’s nut

bolts or replace

7. LT Switch Unit

LT Switch’s cover is intact or not.

LT Switch’s cover keep always

closed to avoid entry of lizards or

moisture

LT Switch or cables are heating

Ensure use of adequate size of

cable as per load after

measurement of load

Cutouts are burnt or broken Replace burnt/broken cutouts

Contacts of LT Switch are

burnt or damaged

Repair or replace with new

Switch

Fuse Wires are of proper size or

not.

Replace fuse wires as per

load

LT Switch or Cut Out are safe

from entry of rainwater /moisture

or not

Ensure to prevent from entry of

rainwater/moisture by sealing

cable ends with PVC Compound

or bend cable ends towards

ground

Bird nest or foreign materials

found in switch

Remove all foreign materials from

switch, clean and tight all

connections.


16. Chart of safe clearances

S. No. Particulars. 33 KV line

11 KV line LT line CEA notification

2010 reference

1 Rural area where no traffic is existing,

ground level to lowest conductors

height shall be

17 Feet 15 Feet 15 Feet Chapter VII sec 58(3)

2 Rural area on along the road, ground

level to lowest conductors height shall

be

19 Feet 19 Feet 18 Feet Chapter VII sec 58(2)

3

Rural area on along the road crossing,

Road level to lowest conductors

height shall be

20 Feet 20 Feet 19 Feet Chapter VII sec

58(1)

4 Vertical clearance over building’s

top level to lowest conductor shall be 12 Feet 10 Feet 8 Feet Chapter VII sec

60(2)(i) & 61(2)(i)

5 Horizontal clearance from building’s

side to nearest conductor shall be 8 Feet 6 Feet 6 Feet Chapter VII sec 60

61(3)(i) & (ii)

6 Clearance from tree branches shall be 8 Feet 6 Feet 4 Feet Chapter VII sec 60 61(3)(i) & (ii)

7 Clearance from 33 KV line shall be 10 Feet 10 Feet 10 Feet Chapter VII sec 59(1)(iv)


17. Breakdown management and Disaster management

Power distribution sketch is self-explanatory that maximum power is transmitted by 33

KV system, lesser by 11 KV and further lesser by LT distribution system. Accordingly,

priority of breakdown management is to be considered. As well as special care to be

considered for top priority to attend where conductor snapping, Fire hazards, sparking,

accidents or pole breakage happened, and rescue operation is urgently required for life

saving. Always keep in mind that “SAFETY FIRST” for life saving.

17.1. Breakdown management of 33 KV System

Superintending Engineer of the circle shall be totally responsible for maintenance and

operation of the 33 KV System.

1. Generally, 33 KV lines emanating from EHV Substations when trips, Relay indications

are noted, then reset, then examine the substation yard within 3 Minutes thereafter on

satisfaction charging given to the VCB of line. If line is charged and load on all three

phase are found equal, then no problem. If there is any difference intimation given to the

concerned SE and 33/11 KV Substations. Voltage and load on all three phase are being

checked continuously at 33/11 KV Substations, if there is any difference, jumper of any

phase might have been opened in between of EHV Substation to the 33/11 KV

Substation. Ground patrolling may be carried out and after identification, repair fault

with due care of safety precautions.

2. While charging of 33 KV line after first tripping’s three minutes, if VCB again tripped

then, second charging is given after 5 Minutes after checking the substation yard.

3. If said 33KV line’s VCB again trips on second charging, feeder is being declared faulty.

Intimation is being given to the concerned SE, DCC and 33/11 KV Substations by EHV

Substation operator. DCC Incharge, Nodal officer of the Circle, Operator of 33/11 KV

Substation shall ensure to intimate to concerned Regional CE and SE by SMS and phone

and he will enter in register with time.

4. Concerned SE will immediately examine the load accomodality on alternate 33 KV

source accordingly operation instructions will be given by him for restoration of supply.

5. Concerned SE will immediately instruct authorized EE/AE to take permit from EHV

Substation within 10 Minutes and thereafter Not to Back Feed Permit from all alternate

source points. SE will ensure for immediate collect staff and start patrolling without

delay.

6. Authorized SE /Engineer may examine the relay indications during first and second

tripping accordingly probable cause of tripping can be assessed. If only over current


indications activated, isolate all load, PTs CTPTs, then megger test for phase to phase

clearance. Collect information from all 33/11 KV Substations regarding any

abnormalities, Indications on any of the VCB but not tripped etc., under such condition,

fault may be persisting on the line or equipment which is not tripped, and indication

activated. Such reflected faults are causing for over current tripping. Other faults like

foreign materials like Kite sticks/semi conducting waste are shorting phase to phase

conductors or conductors shorted/ clearance between Jumpers are inadequate. Clear the

reasoning of faults with due care of safety , megger test, if megger result is not 0Ω,

collect all of staff and officers and take action for permit cancellation. If line is restored,

supply system may be turned back to original feeding system.

7. If Earth Fault indication noticed during tripping, then probable cause may be Insulator

punctured/Conductor snapped and fallen on ground or cross arms/Jumper out and

touched with cross arm or in flash over range/Earth conductor or guard wire snapped and

clubbed with phase wires/Tree branches or wire fallen on conductors/Kite or cloth or

foreign material affixed on insulators and semi conducting during wet condition causing

flash-over. Line staff of the area with past experience may also assess the probable

location of fault. However, on the basis of ground patrolling in sections and megger

testing from source end if Phase to earth value is not 0Ω further action for repair of fault

with due care of safety may be taken there after collect all of staff and officers and take

action for permit cancellation. If line is restored, supply system may be turned back to

original feeding system.

17.2. Breakdown management of 33/11 KV Substation:

Substation Operators are remaining on 24 Hours duty in 33/11 KV Substations. Hence

any happening in the S/s yard or control room is expected to be in the knowledge of duty

operator. Concerned operator shall immediately intimate to the SE and authorized Engineer

regarding happenings. Following reasons or faults may happen in 33/11 KV Substations:-

1. Bird fault with 33 KV VCB/Isolator/Bus/CT/ME/Power transformer.

2. 33 KV or 11 KV Jumper out /burnt.

3. 33 KV or 11 KV Lightening Arrestor ruptured.

4. Insulator of isolator or Bus ruptured.

5. CT/PT/CTPT Unit ruptured.

6. Sparking in earth connections/fire hazards in control cables.

7. Battery charger failed or burnt.

8. DC Circuit short/open circuited.


9. Alarm or indication of power transformer’s Buchhloz relay/Oil temperature/Winding

Temperature activated, or power transformer tripped on such indication.

10. Oil splashed from power transformer with sound.

If any of above natured fault occurred in substation, operator shall trip the incoming

VCB. If VCB is not tripping from control room then, he will (Mechanical) push trip the

incoming VCB and isolate incoming isolator. Please note that isolator or AB Switch shall be

operated only after tripping the VCB. Safety procedures must be followed strictly during

operations. Concerned operator shall immediately intimate to the SE and authorized

Engineers regarding happenings by phone and SMS.

NOTE:- Please note that Substation Operators are not authorized for any work execution in

any 11 KV or 33 KV Bus or equipments.

Authorized engineer shall immediately ensure to attend the faults of 33/11 KV

Substation. If fault occurred with equipments as Power Transformer/CT/CTPT/PT/VCB/

Battery charger EE (STM) shall immediately ensure to attend the faults/investigation and

testing. In case of faults in DC circuit, (O&M) engineer may attend to identify and repair the

fault. In case of fault in Battery Charger STM engineers shall attend to identify and repair

the fault.

17.3. Breakdown management of 11 KV System:

Schematic drawing of Power distribution system shows that quantity of power

distribution by 11 KV System is lesser than of 33 KV System. Accordingly, priority of

breakdown management is to be considered. As well as special care to be considered for top

priority to attend where conductor snapping, Fire hazards, sparking, accidents or pole

breakage happened, and rescue operation is urgently required for life saving. Always keep

in mind that “SAFETY FIRST” for life saving. AS per operational instructions of Executive

Engineer, authorized engineer and line Inspectors shall take Permit to work, collect staff and

start breakdown management work without any delay.

1. Breakdown management of 11 KV System in City area:

Executive engineer shall be responsible for operation and maintenance instructions to

authorized engineers and Line Inspectors for Break down management work of 11 KV lines

emanating from 33/11 KV Substation.

HT maintenance team is deputed for 24 Hours in city area under Assistant Engineer (HT

Maint). 11 lines in city area are general interconnected with A.B. Switch /Isolators with other


11 KV lines in ring main system for isolation or extension of supply.

1. Generally, 11 KV lines emanating from 33/11KV Substations when trips, Relay

indications are noted, then reset, then examine the substation yard within 3 Minutes

thereafter on satisfaction charging given to the VCB of line. If line is charged and load

on all three phase are found equal, then no problem. If there is any difference intimation

given to the concerned SE,EE,AE and Maintenance team. Voltage and load on all three

phase are being checked continuously at 33/11 KV Substations, if there is any difference,

jumper of any phase might have been opened. Low voltage or Dim complaints may be

intimated from consumers. The DTR from which low voltage complaint noticed to the

33/11 KV Substation there may jumper out of 11 KV line. Ground patrolling may be

carried out and after identification, repair fault with due care of safety precautions and

restore supply. Location of jumper out can be assessed based on load. If load on one

phase is 100 Amps and load on other phase is 0→100 or what so ever be, suppose 90

Amps then in computation based on ratio jumper out may be found nearer to the

connected load of 200-300 KVA. Further if load is found 0 Amps then jumper out may

be found nearer to the 33/11 KV Substation.



3. If said 11KV line’s VCB again trips on second charging, feeder is being declared faulty

and outgoing Isolator or A.B. Switch opened. Intimation is being given to the concerned

SE, EE,AE, Maintenance team by Substation operator by SMS and phone and he will

enter in register with time. Executive engineer shall ensure for operation and

maintenance instructions to authorized engineers and Line Inspectors for Break down

management work for immediate action with taking permit to work. Based on fault

indications up to some extent work can be assessed. Collect information from Fuse Off

Call Centre regarding any complaint of flash-over/sounds etc. where chance of fault may

be found.













5. 11 KV faulty line may be sectionalized from feeding end, megger test, if megger result

between phase and earth is not 0Ω then as per satisfactory ground patrolling report,

supply in line in sections may be restored. Other section of this line if found healthy and

satisfactory ground patrolling report, supply to this section may be restored after

isolation from main feed end and extending supply of interconnected other 11 KV line

by back feed.

Note:- Regarding such back-feeding operations, operation instructions shall be given by

single authorized engineer who is expert and well convergent with system. He will ensure

to communicate to all working staff about operations, so that due to communication gap

accident may not take place. Further other healthy 11 KV line may not become faulty due

to extension of supply to faulty 11 KV line. If line is restored, supply system may be turned

back to original feeding system.

2. Breakdown management of 11 KV System in Rural area:

Executive engineer shall be responsible for operation and maintenance instructions to

authorized engineers Asstt. Engineer (Sub Division) and Distribution Centre In-charge for

Break down management work of 11 KV lines emanating from 33/11 KV Substation.

1. Generally, 11 KV lines in rural area are in radial system and not arranged in ring main

system with interconnection of other 11 KV lines. These 11 KV lines are extended to

several Kilometers with branch /tape lines. Continues reading of load and voltage is

being recorded in 33/11 KV Substations. Load in Amps and voltage in KV, in all three

phase is to be nearly same. If load on any phase is noticed different and low voltage /Dim

complaint from consumers, then S/s operator shall intimate by phone and SMS to AE

(Sub Dn.) and In-charge of D/c.AE (Sub Dn.) and In-charge of D/c. under the operation

instructions of EE, shall immediately arrange for patrolling, and necessary actions for

breakdown management without any delay.

2. Generally, 11 KV lines emanating from 33/11KV Substations when trips, Relay

indications are noted, then reset, then examine the substation yard within 3 Minutes

thereafter on satisfaction charging given to the VCB of line. If line is charged and load

on all three phase are found equal, then no problem. If there is any difference intimation

given to the concerned SE,EE,AE and Distribution Center. Voltage and load on all three

phase are being checked continuously at 33/11 KV Substations, if there is any difference,

jumper of any phase might have been opened. Low voltage or Dim complaints may be

intimated from consumers. The DTR from which low voltage complaint noticed to the

33/11 KV Substation there may jumper out of 11 KV line. Ground patrolling may be

carried out and after identification, repair fault with due care of safety precautions and

restore supply. Location of jumper out can be assessed based on load. If load on one

phase is 100 Amps and load on other phase is 0→100 or what so ever be, suppose 90


Amps then in computation based on ratio jumper out may be found nearer to the

connected load of 200-300 KVA. Further if load is found 0 Amps then jumper out may

be found nearer to the 33/11 KV Substation.



4. If said 11KV line’s VCB again trips on second charging, feeder is being declared faulty

and outgoing Isolator or A.B. Switch opened. Intimation is being given to the concerned

SE, EE,AE, Maintenance team by Substation operator by SMS and phone and he will

enter in register with time. Executive engineer shall ensure for operation and

maintenance instructions to authorized engineers and Line Inspectors for Break down

management work for immediate action with taking permit to work. Based on fault

indications up to some extent work can be assessed. Collect information from Fuse Off

Call Centre/D.C. regarding any complaint of flash- over /sounds etc. where chance of

fault may be found.












6. 11 KV faulty line may be sectionalized from feeding end, megger test, if megger result

between phase and earth is not 0Ω then as per satisfactory ground patrolling report,

supply in line in sections may be restored.

17.4. Breakdown management of LT Distribution System:

Assistant engineer, Distribution Center In-charge and Line Inspector shall be

responsible for maintenance and operation for Break down management work of LT

Distribution System. Majority of consumers are directly connected with LT Distribution

System. Hence LT breakdowns management in shortest time is expected for consumer

satisfaction. As such action for accident prevention is to be considered no top priority.

Breakdown on LT lines as snapping of live conductor or AB Cable on road or


buildings or habitated area may invite accidents. Specially snapping of Neutral

conductor/earth wire/guarding wires or Messenger wire of AB Cable may cause fetal

electrical accident due to possibility of return current. Further during fire hazards/flood/Earth

Quake or any other happenings supply in LT may cause accidents. In case of such intimations

first action shall be ensured for isolation of supply for safety and lifesaving.

At present bare LT lines are being converted by AB Cable. In case of intimation of

any breakdown in LT line, concerned line staff shall ensure to isolate supply first thereafter

with safety procedure repair works shall be carried out. In any case joints of AB Cable shall

not be kept open. If any nonstandard joint made temporarily, proper jointer shall be provided

on very next day to avoid theft by hooking.

In case of fire hazards in Marshalling Box of LT AB Cables to Service lines, it should

be replaced on very next day by new one and ensure to keep it closed to prevent from entry

of moisture, birds nest, wires of crow nest etc.

Old bare LT line still exists. To ensure prevention from short circuiting and live wire

may not fall on ground nearer to Distribution Transformers, Bamboo sticks or PVC

Separators shall be invariably provided in 3 Spans from DTR so that DTRs may be prevented

from Short circuit current. Generally, it is noticed that Neutral wire or guarding wires are not

restrung after breakdown. Restringing of Neutral Conductor, Earth Wire, Guarding must be

done with phase conductors so that chances of accident by return current can be avoided.

Birds nest, creepers, Wires of Crow’s nest are generally found on LT lines causing

sparking and fire hazards with PVC service cables. Hence while attending Fuse Off Call

complaints such foreign materials shall be invariably removed. Ensure to provide proper size

of fuse wires after breakdown repair.


18. SAFETY FORM

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19. Sub Permit Safety Form

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------------------ dks iksy Vki isVªksfyax dk;Z djkus gsrq mDr [email protected] dks leLr L=ksr ls vyx djkdj fMLpktZ o

ykbu 'kkVZ djkdj lqj{kk ifj/kh lqfuf'pr dj lc ijfeV iznku djrk gWwA d`I;k ykbu @midj.k fMLpktZ dj lqj{kk

fu;eksa ds ifjikyu ds lkFk dk;Z fu"iknu dj le; ---------------- rd izfronsu nasA vkils izfrosnu ugha izkIr gksus ij

ykbu pkyw djus dh dk;Zokgh ugha dh tk ldsxhA

gLrk{kj ijfeV /kkjh% gLrk{kj lc ijfeV /kkjh%

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fnukad% fnukad%

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eSa----------------------- lc ijfeV /kkjh vkt fnukad -------------------le;------------------- ij ?kks"k.kk djrk gWw fd mijksDr--------------------- ds-

Ogh- ykbu ds [k.M -----------------ls---------------------------------rd iksy Vki isVªksafyx dk;Z izi= ^^c^^ ds vuqlkj djkus ds i'pkr~

leLr isVªksafyx ny] lfgr lHkh vfFkZax] ykbu 'kkVZ fMLpktZ vkfn vyx dj [email protected] dks iqu% ÅftZr djus

gsrq vkt fnukd--------------------- dks le;------------------ ij mijksDr lc ijfeV fujLr djus gsrq izLrqr djrk gWwA

gLrk{kj lc ijfeV /kkjh% gLrk{kj ijfeV /kkjh%

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fnukad% fnukad%

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MADHYA PRADESH POORV KSHETRA VIDYUT VITARAN … Folders/Jabalpur... · operation of 33 KV...

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