11 KV INDOOR BUS BAR
13. Bus Bar Supporting Insulators (broken/chipped,
etc)
14. Bus Bar Spout
15. Feeder Cable Spout
Yes
-
Should be OK and no damage
Yes
-
-
-
Yes
-
-
16. Vermin Proofing
Yes
-
-
-
17. Cleaning of Bus Bar
-
Yes
-
-
Should be OK as per design, intact,
secured and no stresses.
Should be OK as per design, intact
and no stresses.
Should be as per design, intact and
secured
Should be OK. Clean and no dust,
etc.
Tests on 11kV Bus Bar
18. Insulation Resistance test (Megger test)
-
Yes
-
19. DC Hi Pot Test
-
-
Yes
-
Contact Resistance Test for Electrical Joints
-
Yes
-
Should be as per commissioning test
results and/or specifications after
correction of test results at 20 °C
Should be as per commissioning test
results and/or specifications
Good electrical joint has resistance
≤ 5µΩ
1
9. MAINTENANCE OF STATION GROUNDING SYSTEM
A typical Earth Mesh of Grounding System at Grid Station
Equipment Grounding Connection with Earth Mesh
Overhead Ground Conductor Shield/Sky Wire Connections
2
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF STATION GROUNDING SYSTEM
Description of Inspection
and Maintenance Work
1. Visual inspection (A
walk
around
visual
inspection from ground
level and keeping in view
the safe limits of approach
to live and moving parts to
check apparent condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
2. Earth Mesh Layout
Specified Time Period
D/W M3/6
Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
-
-
-
-
3.
Equipment
Ground
Connections
(each
equipment)
4.
Fence
Ground
Connections
5. Station Building Ground
Connections
6. Laying of Overhead
Ground
Conductor
Shield/Sky Wire and Angle
of Protection
7.
Overhead
Ground
Conductor
Shield/Sky
Wire Connections with
earth mesh, Condition,
Fittings, Tension or Sag
8 Direct Earthing of
Overhead
Ground
Conductor
Shield/Sky
Wire at Earth Mast
9. Earth Mesh Conductor
Condition and Connections
with Earth Electrodes
Yes
-
-
-
Should be OK as per Approved
Earth Mesh Layout Plan
Should be OK and intact as per
design
-
Yes
-
-
-
Yes
-
-
Yes
-
-
-
-
-
Yes
-
Yes
-
-
-
Should be OK and intact as per
design
-
-
-
Yes
Should be OK and intact as per earth
mesh design/earth mesh layout plan.
Check by digging the earth as
applicable
Yes
-
-
Should be OK as recommended
(should be < 2 Ω)
-
-
Yes
Should be OK and intact as per
Tests
10. Earth Resistance Test (at Each Equipment Ground
Connections)
11. Earth Mesh Integrity -
Should be OK and intact as per
design/earth mesh layout plan
Should be OK and intact as per
design (separate mast)
Should be OK as per design. A 30°
angle from top of the structure
should be sufficient to protect the
area.
Should be OK and intact as per
design
3
Test (at Each Equipment
design. Comparison of the test
Ground Connections) with
results with commissioning test
300 A Primary Injection
results and/or previous test results
Test Set and/or with Proper
can also be a reference.
Test Set
Note. In heavy polluted areas, give special attention to equipment ground connections and grounding
copper conductor. Follow special instructions in this regard if any.
4
10. MAINTENANCE OF 11KV CIRCUIT BREAKERS
11kV Circuit Breakers Panel Board at 220kV G/S NTDC NKLP Lahore
5
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF 11 KV CIRCUIT BREAKERS
Description of Inspection
and Maintenance Work
1. Visual inspection (A
walk
around
visual
inspection from ground
level and keeping in view
the safe limits of approach
to live and moving parts to
check apparent condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
2. Abnormal Sound and
Smell
3. Panel Board Indication
Lamps
4. Operation Counters
Specified Time Period
D/W M3/6
Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
Yes
-
-
-
-
-
-
-
There should be no abnormal noise,
sound and smell
Should be OK and intact as per
design
Should be OK and intact and
operative
Should be OK and intact as per
design
Should be OK and intact, tight and
secured
-
-
-
-
-
-
Should be OK and intact and
operative
-
-
Should be OK and tight and secured
-
-
Should be OK and no defect/damage
Yes
5. Panel Board Indicating Yes meters
6. Panel Board Ground Yes
Connections (I/C and last
O/G panels)
7. Inter-Panels Ground Yes
Connections
8. LV Compartment: Yes Doors, Door locks, Door
packing, Door stops, Light,
Cleaning, Vermin proofing,
Ground connections, etc.
9.
Space
heaters
& Yes
Thermostat
setting
if
applicable
10. Wiring and Terminal Yes
Blocks
11. Protection Relays and Yes Accessories
Note. LV Compartment are normally sealed
change
CB Trolley & Compartment
12. Trolley Rack IN/OUT Yes way and Floor Level
13. Oil Replacement (for Yes
Should be OK and intact, tight and
secured
Should be OK and no defect/damage
so the inspection and maintenance frequency may
-
-
Should be OK and no defect/damage
-
-
* Replace oil after 6-10 tripping
6
OCB)
and/or*
14. SF6 Gas Pressure (for GCB)
Yes
and/or*
-
15. Contact Wipe Check (for VCB)
Yes
and/or*
]
16. Doors, Door locks,
Door packing, Door stops,
Cleaning, etc.
16.
Auxiliary
Plug
Connector
17.
Panel
Ground
Connections
18. Trolley Rack In/Out
Guide Ways
19. Arm Contacts (Bus
Bar/Cable Side)
20.
CB
Mechanism
(Inspection,
Cleaning,
lubrication, etc.)
21. Trolley Rack In/Out
Locking (Service, Test, and
Withdrawal Positions)
22.CB Major Maintenance /
Overhauling
-
Yes
-
-
whichever comes first. DES of oil >
30kV at 2.5 mm gap. Oil level
should be OK as per indicator. The
indicator should be kept clean and
visible. Should be no oil leakage
* Check SF6 gas pressure after 6-10
tripping whichever comes first,
should be OK as recommended
and/or as per specifications. If
needed makeup SF6gas pressure.
Should be no gas leakage
* Check contact wipe after 6-10
tripping whichever comes first, as
per the method prescribed in the
equipment instruction book. Should
be OK as per design
Should be OK and no defect/damage
-
Yes
-
-
Should be intact as per design
-
Yes
-
-
Should be intact as per design
-
Yes
-
-
Should be intact as per design
-
Yes
-
-
Should be intact as per design
-
Yes
and/or*
-
-
Yes
-
-
*Should be carried out after 6-10
tripping whichever comes first and
should be OK and no defect/damage
Should be intact as per design
-
-
-
Yes
Should
be
recommended
specifications
-
Yes
-
Yes
-
Should be OK and intact as per
design
Should be OK and intact as per
design
Yes
-
Bus Bar & Cable Compartment
23. Bus Bar & Cable Spouts 24. Alignment of Trolley Contacts with Bus Bar &
Cable Spouts. Means for
physical verification of
contact grip.
25.
Power
Cable Termination
-
carried
and/or
out
as
as
per
Should be OK and intact as per
design. Should have no stresses
7
26.
Power
Cable
Sheath/shield Grounding
27.
O/G
Panel
CT
(Mounting,
cleaning,
connections, etc.)
28. I/C Panel CT/PT
(Mounting,
cleaning,
connections, etc.)
Tests
29. Insulation Resistance
Test (Poles, Bus Bar, Power
Cables)
-
-
Yes
-
Should be OK and intact and no
damages
Should be OK and intact/ secured as
per design
-
-
Yes
-
-
-
Yes
-
Should be OK and intact/secured as
per design
-
-
Yes
-
30. DC Hi Pot Test (Poles, Bus Bar, Power Cables)
(special test)
31. Contact Resistance Tests of CB
-
Yes
-
-
Yes
-
32. Vacuum Degree of VCB Interrupters (using
VIDAR or DC Hi Pot set)
32. Contact Wipe Check of VCB Interrupters
-
Yes
-
-
Yes
-
33. Earth Resistance Test of Panel
Board
Ground
connections
Yes
-
-
Should be OK as per commissioning
test
results
and/or
as
per
specifications after correction of test
results at 20 °C
Should be OK as per commissioning
test
results
and/or
as
per
specifications
Should be OK as per commissioning
test
results
and/or
as
per
specifications
Should be OK as per commissioning
test
results
and/or
as
per
specifications
Should be OK as per commissioning
test
results
and/or
as
per
specifications
Should be OK as per commissioning
test results and/or ˂ 2 Ω
8
11. MAINTENANCE OF DC BATTERIES/STATION BATTERY BANK
DC Battery Room at 220kV G/S NTDC Sammundri Road Faisalabad
220 VDC Battery Bank
9
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF DC BATTERIES/STATION BATTERY BANK
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection
from ground level and
keeping in view the safe
limits of approach to live
and moving parts to check
apparent
condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
2. Battery Room Exhaust
Fan
3. Electrolyte Level in Cells
4. Voltage of Pilot Cell (s)
5. Specific Gravity of Pilot
Cell (s)
6. Voltage of each Cell
7. Specific Gravity of each
Cell
8. Battery Stand Level and
Condition
9. Inter-cell Spacing and
Connectors
Specified Time Period
D/W M3/6
Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book..
Yes
-
-
-
Should be OK and operative
Yes
Yes
Yes
-
-
-
-
Yes
Yes
-
-
Yes
-
-
-
Yes
-
Should be OK as per indicator
Should be OK as per specification.
Should be OK as per specifications
after correction of S.G. at 25 °C
Should be OK as per specification
Should be OK as per specification
after correction of S.G. at 25 °C
Should be OK as per design and no
damage
Should be OK as per design, adjust
if required. Connector should be
tightened at recommended torque.
Should be cleaned with water. Do
not rub the ceramic venting plugs
Should be cleaned, and apply nooxide compound.
Put the battery bank on manual
boost charge for 24 hours
Must always be available in battery
room
-
10. Vent Plugs or Filters of Cells
11. Cell terminals Cleaning -
Yes
-
-
Yes
-
-
12. Manual Boost Charge
Yes
-
-
13. Battery Maintenance Yes
Tools and Accessories
(Hydrometer, Thermometer,
Volt
meter,
Insulated
Spanner, Plastic jug, Plastic
funnel, PPE, etc.
Tests
14. Battery Impedance Test -
-
-
-
-
Yes
-
15. Battery Ampere Hour -
-
-
Yes
-
Should be OK as per commissioning
test results and/or specifications.
Replace the suspected cell/s
Arrangements should be initiated for
10
(AH) Capacity Test
replacement of the battery bank if
test AH capacity is ˂ 80%
Correction of SG at 25°C temperature
S25 = St + 0.0007 (t-25) where
S25 = Corrected SG at 25 °C, St = SG at temperature t °C of electrolyte, 0.0007 = assumed
temperature coefficient of SG
Correction of AH discharge capacity at 25°C
C25 = Ct / 1 + 0.008 (t – 25) where
C25 = the discharge capacity corrected at 25 °C, Ct = AH capacity at temperature t °C of electrolyte,
0.008 = assumed temperature coefficient of discharge capacity.
Impedance correction at temperature 77 °F for the conventional flooded battery types or
vented batteries
Zb = 0.008 (Zm) / (T+30)^-0.520 Ω where:
Zb = Corrected battery impedance to 77 °F
Zm = Measured impedance value
T = Measured temperature of electrolyte in °F
Note. This formula is not applicable to Valve-Regulated or sealed cell batteries
11
12. MAINTENANCE OF DC BATTERY CHARGERS
220 VDC Battery Charger at 220kV G/S NTDC NKLP Lahore
12
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF DC BATTERY CHARGERS
Description of Inspection
and Maintenance Work
1. Visual inspection (A
walk
around
visual
inspection from ground
level and keeping in view
the safe limits of approach
to live and moving parts to
check apparent condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
2. Abnormal Sounds and
Smell
3. Vermin proofing
4. Cubicle: Doors, Door
locks, Door packing, Door
stops, Light, Cleaning, etc.
5. Front panel Indication
lamps
6. DC Grounding
Specified Time Period
D/W M3/6
Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
Yes
Yes
-
-
-
Should be OK and no abnormal
sound/smell
Should be OK and intact
Should be OK and no defect/damage
Yes
-
-
-
Should be OK as per design
-
Yes
-
7. Control Switches and
Accessories
8. Automatic Float/Boost
Function
9.
Manual
Float/Boost
Function
10. Float/Boost Voltage
Setting
11. Ripple in output DC
voltage
12.
Indicating
Meters
Accuracy
13. Under/Over Voltage
Protection
14. Current Limiter Setting
15.
Body
Ground
Connections
16. Audible Alarm Function
Yes
-
-
-
Should be no grounding of + or –
DC supply (give attention to
grounding relay)
Should be intact as per design
-
Yes
-
-
-
Yes
-
-
-
Yes
-
-
-
-
Yes
-
-
-
Yes
-
Should be OK as per specifications
(ripples should be < ± 3%)
Should be OK As per specifications
-
-
Yes
-
Should be OK as per specifications
Yes
-
Yes
-
-
Should be OK as per specifications
Should be OK and intact and tight
Yes
-
-
-
Should be OK and intact and
operative
Should be OK and intact and
operative
Should be OK and intact and
operative
Should be OK as per specifications
13
17. Wiring and Terminal Blocks
Yes
-
-
Should be OK and tight and secured
14
13. MAINTENANCE OF AUXILIARY SUPPLY SYSTEM
Three-phase, 250KVA, 11000V/400V Auxiliary Transformers at 220kv G/S
NTDC NKLP Lahore
220VDC, 110DC and 400VAC Auxiliary Supply Panels at 220kv G/S NTDC
NKLP Lahore
15
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF AUXILIARY SUPPLY SYSTEM
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection
from ground level and
keeping in view the safe
limits of approach to live
and moving parts to check
apparent
condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
Auxiliary Transformers
2. Abnormal Sounds and
Smell
3. Vermin Proofing
4. Cubicle: Doors, Door
locks, Door packing, Door
stops, Light, Cleaning,
Proper Glands for Cable
Entrance, Vermin Proofing,
etc.
5. Cable Terminations
6. MCB, Switches and
Fuses
7.
Transformer
Body
Ground Connections
8. Transformer Neutral
Ground Connections
9. Off circuit tap changer
Transformer Tests
10. Insulation Resistance
Test
Specified Time Period
D/W M3/6
Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
Yes
Yes
-
-
-
Should be OK and no abnormal
sound/smell
Should be OK and intact
Should be OK and no defect/damage
Yes
Yes
-
-
-
-
Yes
-
-
-
Yes
-
-
-
-
Yes
-
-
-
-
Yes
-
-
Yes
-
-
-
-
-
-
11. Oil DES Test
Auxiliary Supply Panels (AC/DC)
12. Abnormal Sounds and Yes
Smell
13. Vermin Proofing
Yes
14. Doors, Door locks, Door Yes
packing, Door stops, Light,
Cleaning, Proper Glands for
Should be OK intact and secure
Should be OK and intact as per
design
Should be OK and intact and
secured
Should be OK and intact and
secured
Should be OK and operative
As per commissioning test results
and/or specifications after correction
of test results at 20 °C
DES value should be >30kV
Should be OK and no abnormal
sound/smell
Should be OK and intact
Should be OK and no defect/damage
16
Cable
Entrance,
Cable
Numbering,
Vermin
Proofing, etc.
15. Cable Terminations
Yes
-
-
-
16. MCB, Switches and Yes
Fuses
17. Ground Connections
Yes
-
-
-
-
-
-
18. Wiring and Terminal Blocks
19. DC Grounding Relay
Yes
Yes
-
-
-
-
-
20. No/Loss of AC supply Yes
Relay
-
-
-
21. Space heaters
thermostat
setting
applicable
22. Cable Numbering
Yes
-
-
-
Yes
-
& if
-
Should be OK and intact and
secured
Should be OK and intact as per
design
Should be OK and intact and
secured
Should be OK and tight and secured
Should be OK and intact and
functioning. Test the relay after
every 6 months. Alarm and
indication function should be OK
and intact
Should be OK and intact and
functioning. Test the relay after
every 6 months. Alarm and
indication function should be OK
and intact
Should be OK and intact and
operative
Should be OK and intact and
secured as per scheme
17
14. MAINTENANCE OF SHUNT REACTORS
500 kV 22MVAR Shunt Reactor at 500 kV Grid Station NTDC Sheikhupura
18
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
SHUNT REACTORS
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection from
ground level and keeping in
view the safe limits of
approach to live and moving
parts to check apparent
condition, abnormal noise,
rust on body of the equipment
and component parts, etc.)
2. Oil level: Conservator
Tank Main
Specified Time Period
Remarks/Criteria/Standard/Safety
D/W M3-6 Y1 Y5-10 Precautions
Yes Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
3. Oil level: Bushings
Yes
4. De-railing locking devices
5.Cooling System (AF): Fans
Yes
-
-
-
Yes
Yes
-
-
-
6. Cooling System(OF): Oil Yes
Circulation Pumps
-
-
-
7. Oil Temperature Gauges
8.
Oil
Temperature
Indicators
9. Winding Temperature
Gauges
10. Winding Temperature
Indicators
11. Ground Connections of
Neutral Terminal
Yes
Yes
-
-
-
Should be OK as per indicator. The
indicator should be kept clean and
visible. Should be no oil leakages
Should be OK as per indicator. The
indicator should be kept clean and
visible. Should be no oil leakages
Should be intact as per design
Should be as per transformer
construction design and operative.
Check for proper speed, correct
direction and noisy bearings.
Should be as per transformer
construction design and operative.
Check for correct direction and
noisy bearings.
Should be healthy and accurate
Should be OK at local/remote
Yes
-
-
-
Should be healthy and accurate
Yes
-
-
-
Should be OK at local/remote
Yes
-
-
-
12. Ground Connections of Yes
Body Tank
-
-
-
Measure neutral current with clipon-ammeter to ensure healthy
connection between terminal and the
earth mesh. Transformer neutral is
grounded at two points i.e. with
earth mesh and with separate earth
electrode.
Should be proper and tight. Measure
leakage current with clip-on-
19
13. Silica-gel Breather of Yes
Main Conservator Tank
-
-
-
14. Oil Leakages all around Yes the transformer
15. Bushing Condition (HV, Yes Neutral, etc.)
16.
Bushing
Terminal Yes* Connections (HV, Neutral,
etc.)
-
-
-
-
Yes
-
17. Radiator Tubes Fixture
Yes
-
-
-
18.Radiator Tubes Valves
-
-
Yes
-
19. Pressure Relief Devices (PRD)/Auto Reset Relief
Vent
20. Buchholz Relay
-
-
Yes
-
-
Yes
-
ammeter
to
ensure
healthy
connection between the body tank
and earth mesh. Transformer body
tank has two grounding points.
Bubbling in the oil indicates healthy
breathing. The colour of silica-gel
should be BLUE and oil in glass pot
clean. If 1/3 volume of the silica-gel
has changed colour into PINK then
recondition of replace the whole
silica-gel
Should be no oil leakages
Should be neat and clean, no
damages and no oil leaks
Dismantle
connections,
clean
properly, apply corrosion inhibitor
and fix/tight with recommended
torque. Should be no hotspot/s (*
check
during
night
patrolling/thermovision
survey).
While handling bushing terminal
connections, take care of oil sealing
system, arcing horns (if provided),
the spacing between electrodes
should be as per recommendations
and/or in accordance with 1cm per
kV of the rated phase-to-ground
voltage. In 500/220 transformers,
tertiary winding terminals are
enclosed in separate cubicle, give
special attention to water proofing
and vermin proofing of the cubicle.
Should be secured with proper
clamping/supports
The valves should always be kept
opened, operative and no oil leaks
(the temperature of radiator tubes
should be observed by touching the
tubes and feeling the degree of
hotness by comparison with each
other tube
Should be intact, no damages, and
healthy micro switch and wiring
terminal connections
Should be operative, no damages,
20
arrow
mark
points
toward
o
conservator tank, 0.5
to 1o
ascending level towards conservator
tank, gas sampling valve operative
(in some models a separate device
for gas collection is provided near
ground level of the transformer tank)
, no oil leaks, cover packing healthy,
neat & clean, proper glands at
wiring cable entrance and moisture
proofing, wiring terminals tight,
velocity setting (65/100/150 cm per
second, factory setting is normally at
100 cm/s), etc.
Control Cubicle
21. Doors, Door locks, Door
packing, Door stops, Light,
Cleaning,
Ground
connections, Proper glands at
wiring cable entrance, Wiring
cable numbering, Vermin
proofing, etc.
22.
Space
heaters
&
Thermostat setting
23. Wiring and Terminal
Blocks
24. Control Switches and
Accessories
Tests
25. DES test of Oil of main
tank
and
OLTC
compartments
26. Chemical Analysis of Oil
Yes
-
-
-
Should be OK and no defect/damage
-
Yes
-
-
Should be intact and operative
-
-
Yes
-
Should be tight and secured
-
Yes
-
-
Should be as per design, healthy and
secured
-
-
Yes
-
-
-
-
Yes
27. Tangent Delta (Tan δ) test of Oil
28. Dissolved Gases Analysis (DGA) of oil
29. Insulation Resistance test (Megger test) of Windings
-
-
Yes
-
Yes
-
-
Yes
-
30. Insulation Resistance test (Megger test) of Core and/or
Clamping
31.
Capacitance
and Dissipation
Factor
test
-
Yes
-
-
Yes
-
DES value should be >30kV, 40kV,
50kV at 2.5 mm gap for 66kV,
132kV, 220kV/ 500kV respectively
Should be as per test laboratory
specifications
Should be as per test laboratory
specifications
Should be as per test laboratory
specifications
Should be as per commissioning test
results and/or specifications after
correction of test results at 20 °C
Should be as per commissioning test
results and/or specifications after
correction of test results at 20 °C
Should be as per commissioning test
results and/or specifications after
21
(C&DF test) of windings and
bushings
32. Winding Resistance test
-
-
Yes
-
correction of %DF test results at 20
°C
Should be as per commissioning test
results and/or specifications after
correction of test results at 75 °C(*)
Should be as per commissioning test
results and /or factory test results
Should be OK and intact
33.
Sweep
Frequency Yes
Response Analysis (SFRA)
34.
Buchholz
Relay Yes functional tests; Alarm and
Trip, Indications and Alarm
35. Oil temperature; Alarm Yes Should be OK and intact
and Trip test, Indications and
Alarm
36. Winding temperature; Yes Should be OK and intact
Alarm
and
Trip
test,
Indications and Alarm
37. Pressure Relief Device Yes Should be OK and intact
(PRD); Trip test, Indications
(local,
mechanical
and
remote) and Alarm
Note. CORRECTION OF INSULATION RESISTANCE TEST RESULTS AT STANDARD
TEMP ERATURE 20 °C
Because most of the insulation materials have a negative temperature co-efficient i.e. , the resistance
decreases with increase in temperature, so the IR value should be corrected to a standard temperature
of 20 °C.
Roughly IR value decreases to ½ of its value for every 10 °C rise in the temperature above 20
°C. So for correction at 20 °C, for every 10 °C rise in the temperature above 20 °C, increase the
measured value to 2 times. Formula for accurate temperature correction calculations;
IR 20 = IRt x 2^(t – 20) /10
where IR 20 is the corrected value at 20°C, t is the temperature of insulation mass and IRt is
the measured insulation resistance value at temperature t °C.
IR value is usually in mega ohms (M Ω).
Note. CORRECTION OF WINDING RESISTANCE TEST RESULTS AT STANDARD
TEMPERATURE 75 °C
The measured of winding resistance value should be corrected to a standard temperature of 75 °C.
R 75 = Rt (235 + 75) / (235 + t) Ω
where R 75 is the corrected value at 75°C, t is the winding temperature and Rt is the measured
winding resistance value at temperature t °C.
22
15. MAINTENANCE OF GIS SUB STATTION
220kV GIS System at University Grid Station Islamabad
23
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF GIS SUB STATION
Description of Inspection and
Maintenance Work
1. Visual inspection (A walk
around visual inspection from
ground level and keeping in view
the safe limits of approach to live
and moving parts to check
apparent condition, abnormal
noise, rust on body of the
equipment and component parts,
position of opening and closing
indicators, etc.)
2. Test Operation of Ventilation
Fans from Control at each
Entrance Door of GIS Hall
3. Test Operation of Warning
Bells
4. Availability of Respirators at
each Entrance Door of GIS Hall
5. Unusual Noise in Switchgear
and Bus Bar Ducts
6. SF6 Gas Pressure (GCB)
Specified Time Period
D/W M3-6
Y1
Y5/10
Yes -
Remarks/Criteria/Standard/
Safety Precautions
Wear PPE and carry basic
tools, multi-meter, clip-onammeter, etc. Make entries of
the observations in check
sheets/note book.
Yes
-
-
-
Should be OK
defect/damage
Yes
-
-
-
Yes
-
-
-
Yes
-
-
-
Yes
-
-
-
7. Steel Structure Ground Yes
Connections
8.
HV
In/Out
Terminal Connections
-
-
-
Should be OK and no
defect/damage
Respirators should always be
available
There
should
be
no
unusual/abnormal noise
Should be OK as per rated
pressure/indicator
and
corrected at temperature 20
°C (*). The indicator should
be kept clean and visible.
Should be no gas leakages
*(+0.025 bar for every 1°C
above 20 °C)
Should be OK as per design
-
Yes
-
9.
Supporting
Structure Nut/Bolts/Level
10.
Alignment
Check
of Disconnecting Switches/Isolators,
as applicable
Yes
-
-
Yes
-
-
and
no
Dismantle connections, clean
properly, apply corrosion
inhibitor and fix/tight with
recommended torque. Should
be no hotspot/s (check during
night patrolling/thermovision
survey)
Should be OK as per design,
and tight and secured
Should be OK as per
provision in design and check
method (in SE Switzerland
make system at Ravi GIS
24
11. Visual Check of CB Contacts
Through Inspection Glass Hole,
as applicable
12. CTs; Secondary Terminal
Box: Cover, Cover locks, Cover
packing, Cleaning, Proper glands
at wiring cable entrance, Wiring
cable
numbering,
Vermin
proofing, Ground connections,
etc.
13. CTs; Secondary Terminal
Connections
14. PTs; Secondary Terminal
Box: Cover, Cover locks, Cover
packing, Cleaning, Proper glands
at wiring cable entrance, Wiring
cable
numbering,
Vermin
proofing, Ground connections,
etc.
15. PTs; Secondary Terminal
Connections
16. Earthing connections /
Terminals
Control Cubicles
17. Cubicle Doors, Door locks,
Door packing, Door stops, Light,
Cleaning, Proper glands at wiring
cable entrance, Wiring cable
numbering, Vermin proofing,
Ground connections, etc.
18. Control switches, Key
switches,
Indications,
Accessories, etc.
19. Space heaters & Thermostat
setting
20. Wiring and Terminal Blocks
substation
Lahore,
this
alignment is checked by
inserting a Teflon pin in the
check holes)
Should be OK as per
provision in design and check
method (in SE Switzerland
make system at Ravi GIS
substation Lahore, provision
has been made for visual
check of the CB contacts
through an inspection glass
hole)
Should be OK and no
damage/no defect, water
proofing & vermin proofing
intact
Yes
-
-
-
-
-
Yes
-
Should be tight and secured
Yes
-
-
-
Should be OK and no
damage/no defect, water
proofing & vermin proofing
intact
-
-
Yes
-
Should be tight and secured
Yes
-
-
-
Should be tight and secured
Yes
-
-
-
Should be OK
defect/damage
and
no
Yes
-
-
-
Should be OK
defect/damage
and
no
Yes
-
-
-
Should be intact and operative
-
-
Yes
-
Should be tight and secured
25
21. Operation Counter
Yes CBs; Motor Spring Operating Mechanisms
22. Cubicle Doors, Door locks, Yes Door packing, Door stops, Light,
Cleaning, Proper glands at wiring
cable entrance, Wiring cable
numbering, Vermin proofing,
Ground connections, etc.
23. Control switches, Key Yes switches,
Indications,
Accessories, etc.
24. Space heaters & Thermostat Yes setting
25. Wiring and Terminal Blocks
26. Operation Counter
Yes 27. Cleaning
Yes 28. Closing Spring Motor Charging Time
-
-
Should be intact and operative
-
-
Should be OK
defect/damage
and
no
-
-
Should be OK
defect/damage
and
no
-
-
Should be intact and operative
Yes
Yes
-
29.
Lubrication
of Yes
moving/sliding/rolling parts
30. Closing Dash Pot Oil Level
Yes
31. Opening Dash Pot Oil Level
Yes
32. Manual Charging of Closing Yes
Spring
33.
Supporting
Structure Yes
Nut/Bolts/Level
34. CB Close/Open or ON/OFF
Indication (electrical/mechanical
indicators)
CBs; Hydraulic Oil Pressure Operating Mechanisms
35. Cubicle Doors, Door locks, Yes Door packing, Door stops, Light,
Cleaning, proper glands at wiring
cable entrance, Wiring cable
numbering, Vermin proofing,
Ground connections, etc.
36. Control switches, Key Yes switches,
Indications,
Accessories, etc.
37. Space heaters & Thermostat Yes setting
38. Wiring and Terminal Blocks
Yes
39. Operation Counter
Yes 40. Hydraulic Oil Level
Yes 41. Hydraulic Oil Replacement
-
-
Should be tight and secured
Should be intact and operative
Should be OK neat and clean
Should
be
OK
as
recommended (usually <
15sec)
Should be OK as per
recommendations
Should be OK as per design
Should be OK as per design
Should be OK as per design
-
Should be OK as per design,
tight and secured
Should be in accordance with
the actual position of CB and
OK as per design
-
Should be OK
defect/damage
and
no
-
Should be OK
defect/damage
and
no
-
Should be intact and operative
Yes
Should be tight and secured
Should be intact and operative
Should be OK as per design
Should be replaced as per
26
42. Hydraulic Oil Pressure
43. Hydraulic Oil Leakages
44. N2 Gas Pressure
45. Hydraulic Oil: Low Pressure
Alarm and Lockout Check
46. Hydraulic Oil Filter Check
recommendations
Should be OK as per design
Should be no leakages
Should be OK as per design
Should be OK as per design
and remote indications
Should be OK as per design,
clean or replace the filter as
per recommendations
Should be OK as per
recommendations
Should be OK as per
recommendations
Should be OK as per design,
Tight and secure
Yes
Yes
-
-
Yes
Yes
-
-
-
Yes
-
47. Hydraulic Oil Pressure Safety Valve Function Check
48. Hydraulic Oil Pump: Cut IN/OUT Pressure Value Check
49. Hydraulic Oil Pump and Yes
Accessories Mounting Structure
Nut/Bolts/Level
CB; Pneumatic Operating Mechanisms
50. Cubicle Doors, Door locks, Yes
Door packing, Door stops, Light,
Cleaning, proper glands at wiring
cable entrance, Wiring cable
numbering, Vermin proofing,
Ground connection, etc.
51. Control switches, Key Yes
switches,
Indications,
Accessories, etc.
52. Space heaters & Thermostat
Yes
53. Wiring and Terminal Blocks
54. Operation Counter
Yes
55. Rated Air Pressure
Yes
56. Rated Air Pressure: Low Pressure Alarm and Lockout
Check
57. Air Compressor: Air Intake Filter Check
-
Yes
-
-
Yes
-
-
-
-
-
-
-
Should be OK
defect/damage
and
no
-
-
-
Should be OK
defect/damage
and
no
Yes
-
Yes
-
Should be intact and operative
Should be tight and secured
Should be intact and operative
Should be OK as per design
Should be OK as per design
and remote indications
Yes
-
-
58. Air Compressor: Lubrication
Oil Level and Condition Check
59. Air Compressor: Operation
Hours Counter Check
60. Air Pressure: Safety Valve
Function Check
61.
Air
Compressor
and
Accessories Mounting Structure
Nut/Bolts/Level
Tests
-
Yes
-
-
Yes
-
-
-
Should be OK as per design,
clean or replace filter as per
recommendations
Should be OK as per design,
replace oil as recommended
Should be intact and operative
-
-
Yes
-
Yes
-
-
Should be OK as per
recommendations
Should be OK as per design,
and tight and secured
27
62. Test Operation: ON/OFF
Local/Remote/Auto
63. CB Position Mechanical
Indication (ON/OFF)
64. D/S or Isolator Position
Mechanical Indication (ON/OFF)
65. SF6 Gas Purity Test (GCB)
66. SF6 Dew Point/Moisture
Contents Test (GCB)
-
-
Yes
-
Yes
-
-
-
Yes
-
-
-
-
-
Yes
Yes
-
67. Contact Resistance Test
-
-
Yes
-
68. Close/Open Time Test
-
-
Yes
-
69. Anti-Pumping Feature Check 70. Pole Discrepancy Control Feature Check
(applicable
in
single-pole
operated CBs)
71.
Minimum
Voltage Close/Open Test
-
Yes
Yes
-
-
Yes
-
72. SF6 Gas: Low Pressure Alarm and Lockout Check
-
Yes
-
Should be intact and operative
along with remote indications
Should be correct as per
actual position
Should be correct as per
actual position
Purity should be > 97 %
Dew point should be >-15°C
or Moisture contents should
be < 50 PPM
Should
be
OK
as
recommended
Should
be
OK
as
recommended.
The
permissible
differences
between timings of 3-poles
and between timings of
breaks within 1-pole are:
Closing time: 5ms (1/4 cycle)
Opening time: 3.33ms (1/6
cycle)
Within breaks of 1-pole:
2.5ms (1/8 cycle)
Should be OK and intact
Should be OK and intact,
remote indication
The CB should open at 5075% voltage of rated value
and close at 80% voltage of
rated value
Should be OK as per design
and remote indications
28
16. MAINTENANCE OF POWER CABLES AND CONTROL CABLES
11kV Power Cables Connected with
132/11 kV Power Transformer
Control Cables laid in Trench
132kV XLPE Power Cables
Connected with 132kV GIS System
at 220kV GIS University Islamabad
Control Cables Coming from Cable room.
29
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECK/TESTS
OF POWER CABLES AND CONTROL CABLES
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection
from ground level and
keeping in view the safe
limits of approach to live
and moving parts to check
apparent
condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
2.
Cable
Marking
/
Numbering
3. Cable Terminations and
Shield Ground
4. Oil Pressure in OilFilled Cables
5. Patrolling along the
Cable Route
Specified Time Period
D/W M3/6
Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
Should be OK as per design
-
Yes
-
-
-
-
-
-
Should be OK and intact and
secured as per design
Should be OK as recommended
-
Yes
-
-
6. Control Cables Laying (runners, cable hangers,
cable
raceways,
cable
trays, in the trenches and
cable room, etc.)
Tests
7.
Capacitance
and Dissipation
Factor
test
(C&DF test)
Yes
-
-
-
Yes
-
8. Insulation Resistance test (Megger test)
-
Yes
-
Patrolling should be carried
regularly, there should be no
damage, no encroachment, etc along
the cable route.
Should be OK as per design
Should be as per commissioning test
results and/or specifications after
correction of %DF test results at 20
°C
Should be as per commissioning test
results and/or specifications after
correction of test results at 20 °C
Note.
1. Each length of cable should be calculated according to requirements of design and route to reduce
the cable joints.
2. Power cables and control cables should not be placed on the same line of the support.
3. In the three phase four wire system, the cable with four cores should be applied. The cables with
three cores combined with another single cable or wire must be forbidden and the metal sheath of
three core cables cannot be used as the neutral line.
4. The electric power cables which are servicing in a parallel formation, both cable type and length
30
shall be same.
5. The distance among each supporting point and bend radius should comply with the requirement of
the design.
6. High and low voltage power cable and control cable should be placed in sequence.
7. DC supply and AC supply control cable should be placed in sequence.
8. Installation of Cable in Pipe; The cable pipes should be clean before the cable is installed. There
should be no ponding or sundries in the pipe. When the cable is installed, the protective cover
layer should not be damaged. The non-corrosive lubricant/powder should be applied.
9. Installation of cable directly buried; There may be mechanical damage, chemical damage,
underground current, vibration, heat, humid substances, and insect damage to underground cable,
therefore the protective measure should be applied.
10. The soft soil and sand should be covered under and on the cable no less than 100mm and the
protective cover should be placed. The covered width should be more than 50mm of the two sides
of the cable. The protective cover could apply concrete plate or brick. There should be no stone or
other substance in the soft soil and sand.
11. The marking signs should be installed at the turning corner, straight joints connection position of
cable routine at regular intervals in cable route.
31
17. MAINTENANCE OF SHUNT CAPACITOR BANKS
11kV Capacitor Bank at 220kV Grid Station NTDC NKLP Lahore
32
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
SHUNT CAPACITOR BANKS (132KV & 11KV)
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection from
ground level and keeping in
view the safe limits of
approach to live and moving
parts to check apparent
condition, abnormal noise,
rust on body of the equipment
and component parts, etc.)
2. Capacitor Tank Condition
Specified Time Period
Remarks/Criteria/Standard/Safety
D/W M3-6 Y1 Y5-10 Precautions
Yes Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
3. Capacitor Oil Leakage
4. Fuses Condition (for 11kV
only)
5. De-railing locking devices
6.Bus
Bar
or
Line
Connections
Yes
Yes
-
-
-
Yes
-
-
Yes
-
7.Ground Connections
8.
Supporting
Structure
Nut/Bolts/Level
9.
Porcelain
Insulators
Condition
10.Neutral CT Condition
Yes
-
Yes
-
-
Yes
-
-
-
Yes
-
-
-
11. Neutral CT Connections (P1&P2)
-
Yes
-
12. Oil Level in Neutral CT Yes
(132kV only)
-
-
-
13. 132kV Neutral CT: Yes
Secondary Terminal Box:
Cover, Cover locks, Cover
-
-
-
Tank body should be intact and have
no signs of bulging or rupture. OK
as per indicator. The capacitor unit
should be kept clean
Should be no oil seepage or leakages
Should be OK as per design
Should be intact as per design
Dismantle
connections,
clean
properly, apply corrosion inhibitor
and fix/tight with recommended
torque. Should be no hotspot/s
(check
during
night
patrolling/thermovision survey).
Should be OK as per design
Should be OK as per design, and
tight and secured
Should be clean and no damage
Should be OK as per design, and
tight and secured
Dismantle
connections,
clean
properly, apply corrosion inhibitor
and fix/tight with recommended
torque. Should be no hotspot/s
(check
during
night
patrolling/thermovision survey)
Should be OK as per indicator. The
indicator should be kept clean and
visible. Should be no oil leakages
Should be OK and no damage/no
defect, water proofing & vermin
proofing intact
33
packing, Cleaning, Proper
glands at wiring cable
entrance,
Wiring
cable
numbering, Vermin proofing,
Ground connections, etc.
14. Neutral CT: Secondary Terminal Connections
15. Grounding/Discharging Switch Condition
Tests
16. Capacitance Test of Bank or unit Capacitor (or C&DF
Test as applicable).
C&DF Test of Neutral CT
-
Yes
-
Should be tight and secured
-
Yes
-
Should be OK as per design, and
operative and secured
-
-
Yes
17. Insulation Resistance test (Megger test) of Insulators
-
-
Yes
18. Neutral CT: Magnetizing or Exciting Current/KneePoint Voltage Test (special
test)
19.Neutral CT: Current Ratio and Accuracy Test (special
test)
-
-
Yes
Should be as per name plate data or
commissioning test results and/or
specifications after
correction of %DF test results at 20
°C
Should be as per commissioning test
results and/or specifications after
correction of test results at 20 °C
Should be as per commissioning test
results and /or specification
-
-
Yes
As per selected primary/secondary
current ratio and /or specifications.
Accuracy test results should be in
accordance with the relevant
Metering/
Protection
core
specifications.
Note.
1) All capacitor units in the bank must be of the same Voltage rating and KVAR rating.
2) Upon damage of one or more capacitor units in the bank, it must be ensured to avoid voltage
in excess of 110% on the remaining units in a group in each phase.
3) Before working on capacitor units, these must be discharged completely.
34
18. MAINTENANCE OF FIRE DETECTION AND FIRE FIGHTING
ARRANGEMENTS
Fire Fighting arrangements at Grid Station
35
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECK/TESTS
OF FIRE DETECTION AND FIRE FIGHTING ARRANGEMENTS
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection
from ground level and
keeping in view the safe
limits of approach to live and
moving parts to check
apparent condition, abnormal
noise, rust on body of the
equipment and component
parts, etc.)
2. Fire/Smoke detectors
Specified Time Period
D/W M3/6 Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
-
Yes
-
-
3. Water Sprinkling System
(heat sensors, water supply
and water storage tanks,
piping,
valves/regulators,
etc.)
4. Oil Sump below the
Transformers
5. Nitrogen Gas (N2)
Injection System (Surgisystem) for Transformers
6. Portable fire extinguishers
chemical-foam type, CO2 gas
type, etc.
7. Sand Buckets, Water
Buckets, Shawls,
8. Partition Wall between
Transformers
Yes
-
Yes
-
Should be OK as per design intact
and operative
Should be OK as per design intact
and operative
Yes
-
-
-
Yes
-
-
-
Yes
-
-
-
Should be OK and as per design,
intact and operative
Yes
-
-
-
Yes
-
-
-
Should be OK and as per design,
intact and useable
Should be OK and as per design, and
intact
Should be OK and intact as per
design
Should be OK as per design, intact
and operative
36
19. MAINTENANCE OF ARRANGEMENTS FOR WORK SUPPORT AND
FACILITIES AT CONTROL BUILDING
A view of Control Room at 220kV G/S NTDC NKLP Lahore
37
SOP CHECK SHEET: MAINTENANCE SCHEDULE OF ARRANGEMENTS
FOR WORK SUPPORT AND FACILITIES AT CONTROL BUILDING
Description of Inspection
and Maintenance Work
1. Visual inspection of
control and office buildings
(A walk around visual
inspection from ground level
and keeping in view the safe
limits of approach to live and
moving parts to check
apparent condition, abnormal
noise, rust on body of the
equipment and component
parts, etc.)
2. Safety and security
arrangements,
3. Work support provisions
and facilities at Control
room, Relay room, Battery
room, Offices, Stores, Wash
rooms,
etc.
(cleaning,
drinking
water
supply,
standby electricity supply
arrangements,
emergency
lights, air conditioning,
doors
fittings,
window
fittings, fire detection, fire
protection and fire fighting,
personal
protective
equipment
(PPE),
distribution supply boards,
first-aid-arrangements,
emergency exits, safety
awareness arrangements of
the employees, etc.)
4. Lightning Arrangements
(including
emergency
lights)
Specified Time Period
D/W M3/6 Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
Yes
-
-
-
Should be OK intact and secured as
per yardstick requirements
Should be intact and secure as per
yardstick requirements
Yes
-
-
-
Should be OK as per design, intact
and operative
38
20. MAINTENANCE OF ARRANGEMENTS FOR WORK SUPPORT AND
FACILITIES AT OUTDOOR SWITCH YARD AREA
Outdoor Switch Yard at 220kV Grid Station NTDC NKLP Lahore
39
SOP CHECK SHEET: MAINTENANCE SCHEDULE OF ARRANGEMENTS
FOR WORK SUPPORT AND FACILITIES AT OUTDOOR SWITCH YARD
AREA
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection
from ground level and
keeping in view the safe
limits of approach to live and
moving parts to check
apparent condition, abnormal
noise, rust on body of the
equipment and component
parts, etc.)
2. Lightning Arrangements
Specified Time Period
D/W M3/6 Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
security Yes
-
-
-
4. Transformer ways
Yes
-
-
-
5. Roads/walking ways
Yes
-
-
-
6. Sanitation , rain water
drainage
and
disposal
arrangements
7. Overall cleaning and
pollution free atmosphere
(maintenance of lawns,
dealing with wild growth,
etc.)
8. Elimination or control of
hazardous conditions for
safety of the employees and
the equipment.
9. Cable Trenches and
Covers
Yes
-
-
-
Should be OK as
and operative
Should be OK
secured
as
requirements
Should be OK
operative
Should be OK
operative
Should be OK
operative
Yes
-
-
-
Should be OK and cleaned, intact
and secured
Yes
-
-
-
Adequate
safety
should be made
Yes
-
-
-
Should be OK and cleaned, intact
and secured
3. Safety and
arrangements,
per design, intact
and intact and
per
yardstick
and intact and
and intact and
and intact and
arrangements
40
21. MAINTENANCE OF ARRANGEMENTS FOR LIVING SUPPORT AND
FACILITIES AT RESIDENTIAL COLONY OF THE GRID STATION
Mosque at Residential Colony of 220kV Grid Station NTDC NKLP Lahore
41
SOP CHECK SHEET: MAINTENANCE SCHEDULE OF ARRANGEMENTS
FOR LIVING SUPPORT AND FACILITIES AT RESIDENTIAL COLONY OF
THE GRID STATION
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection
from ground level and
keeping in view the safe
limits of approach to live and
moving parts to check
apparent condition, abnormal
noise, rust on body of the
equipment and component
parts, etc.)
2. Safety and security
arrangements
3. Drinking Water Supply
Specified Time Period
D/W M3/6 Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
Yes
-
-
-
4.
Roads/Streets/walking
ways/Parks
5. Sanitation , rain water
drainage
and
disposal
arrangements
6. Overall cleaning and
pollution free atmosphere
(maintenance of lawns,
dealing with wild growth,
etc.)
7. Elimination or control of
hazardous conditions for
safety of the residents.
Yes
-
-
-
Yes
-
-
-
Should be OK intact and secured as
per yardstick requirements
Should be OK, clean/safe and
secured as design
Should be OK and intact and
operative
Should be OK and intact and
operative
Yes
-
-
-
Should be OK and cleaned
Yes
-
-
-
Adequate
safety
should be made
arrangements
42
6.
MAINTENANCE SCHEDULE AND CHECKS OF PROTECTION
RELAYS AND INSTRUMENTAION (P&I)
Preventive maintenance is a cycle of planned inspections, work activities and tests to
be implemented to get and ensure for safe and reliable performance of different
equipment and infrastructure components of the grid system. The maintenance cycle
or frequency of implementation is given in terms of time-periods which can be
modified due to weather conditions and constraints of the man-hours and quantity of
the equipment in the jurisdiction of the work crew.
Periodic maintenance tests of protection relays/instruments and other devices are
required to identify failure and degradation in service, so that corrective action can be
taken. Because a protection scheme only operates under fault conditions, defects may
not be revealed for a significant period of time, until a fault occurs. Regular testing
assists in detecting faults that would otherwise remain undetected until a fault occurs.
The check sheets given hereunder describe only the maintenance schedules and
checks/tests in terms of what to do and when to do. For the aspect of how to do, one
should consult relevant manufacturer’s instructions, TSG training course books and/or
TSG technical experts. In addition to the inspection and maintenance activities given
in this SOP, manufacturer’s recommended instructions are also applicable.
The symbols used for time-periods for inspection and maintenance/frequency of
implementation are as under:
D stands for daily,
W stands for weekly,
M stands for monthly,
Y stands for yearly.
43
A view of Relay Room at 220 kV NTDC G/S NKLP Lahore
An old Model Distance Protection Relay L8b & LZ 32 at 220 kV NTDC G/S
NKLP Lahore
44
6.1 MAINTENANCE OF CONTROL PANELS (CP)
45
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF CONTROL PANELS (CP)
Description of Inspection
and Maintenance Work
1. Visual inspection (A walk
around visual inspection
from ground level and
keeping in view the safe
limits of approach to live
and moving parts to check
apparent
condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
2. Abnormal Sounds and
Smell
Vermin Proofing
3. Indications bulbs/lamps
Specified Time Period
D/W M3/6 Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools, multimeter, clip-on-ammeter, etc. Make
entries of the observations in check
sheets/note book.
Yes
-
-
-
Yes
Yes
-
-
-
4. Semaphore Indicators
Yes
-
-
-
5. Indication Test/Reset
Buttons
6. Indicating Meters AC &
DC
7. Audible Alarm (Hooter)
8. Control Markings
9. Doors, Door locks, Door
packing, Door stops, Light,
Cleaning, Proper Glands for
Cable Entrance, etc.
10. Cable Terminations
11. Cable Numbering
Yes
-
-
-
Should be OK and no abnormal
sound/smell
Should be OK and intact
Should be OK and healthy as per
design
Should be OK and healthy as per
design
Should be OK and intact and operative
Yes
-
-
Yes
Yes
Yes
-
-
--
Should be OK and healthy as per
design
Should be OK and intact and operative
Should be OK as per design
Should be OK and no defect/damage
Yes
-
-
Yes
-
12. MCB, Switches and
Fuses
13. Wiring and Terminal
Blocks
14. Ground Connections
15. Space heaters &
thermostat
setting
if
applicable
Yes
-
-
-
Should be OK and intact and secure
Should be OK and intact and secured
as per scheme
Should be OK and intact as per design
-
Yes
-
-
Should be OK and tight and secured
Yes
-
Yes
-
-
Should be OK and tight and secured
Should be OK and intact and operative
46
6.2 MAINTENANCE OF PROTECTION RELAY PANELS (RP)
Front view of Protective Relay Panels
Back side view of Protective Relay Panels
47
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF PROTECTION RELAY PANELS (RP)
Description of Inspection
and Maintenance Work
1. Visual inspection (A
walk
around
visual
inspection from ground
level and keeping in view
the safe limits of approach
to live and moving parts to
check apparent condition,
abnormal noise, rust on
body of the equipment and
component parts, etc.)
2.Abnormal Sounds and
Smell
3. Vermin Proofing
4. Relay Fittings
Specified Time Period
D/W M3/6
Y1 Y5/10
Yes -
Remarks/Criteria/Standard/Safety
Precautions
Wear PPE and carry basic tools,
multi-meter, clip-on-ammeter, etc.
Make entries of the observations in
check sheets/note book.
Yes
-
-
-
Yes
Yes
-
-
-
5. Relay Indication Lamps,
Flags, etc.
6.
Control
Number
Markings
7. Doors, Door locks, Door
packing, Door stops, Light,
Cleaning, Proper Glands for
Cable Entrance, etc.
8. Cable Terminations
Yes
-
-
-
Yes
-
-
-
Should be OK and no abnormal
sound/smell
Should be OK and intact
Should be OK and intact and
secured
Should be OK and intact and
secured
Should be OK as per design
Yes
-
-
-
Should be OK and no defect/damage
Yes
-
-
-
9. Cable Numbering
-
-
Yes
-
10. MCB, Switches and
Fuses
11. Wiring and Terminal
Blocks
12. Ground Connections
13. Space heaters &
thermostat
setting
if
applicable
Yes
-
-
-
-
Yes
-
-
Should be OK and intact and
secured
Should be OK and intact and
secured as per scheme
Should be OK and intact as per
design
Should be OK and tight and secured
Yes
-
Yes
-
-
Should be OK and tight and secured
Should be OK and intact and
operative
48
6.3 MAINTENANCE OF TRANSMISSION LINE PROTECTION RELAYS
AND INSTRUMENTATION (P&I)
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF
TRANSMISSION
LINE
PROTECTION
RELAYS
AND
INSTRUMENTATION (P&I)
Note. The Electromechanical relays have to be checked and tested annually as recommended below,
whereas for the Numerical relays the test schedule should be on 5-10 yearly bases
Description of Inspection Specified Time Period
Remarks/Criteria/Standard/Safety
and Maintenance Work
D/W M3/6 Y1 Y5/10 Precautions
1. Visual inspection (A walk Yes Wear PPE and carry basic tools,
around visual inspection
multi-meter, clip-on-ammeter, etc.
from ground level and
Make entries of the observations in
keeping in view the safe
check sheets/note book.
limits of approach to live
and moving parts to check
apparent
condition,
abnormal noise, rust on body
of the equipment and
component parts, etc.)
2.
Distance/Impedance Yes Should be OK as per specifications
Protection Relays
and protection scheme
3. Over Current Protection Yes Should be OK as per specifications
Relays
and protection scheme
4. Earth Fault Protection Yes Should be OK as per specifications
Relays
and protection scheme
5.
Under
Frequency Yes Should be OK as per specifications
Protection Relays
and protection scheme
6. Under Voltage Protection Yes Should be OK as per specifications
Relays
and protection scheme
49
6.4 MAINTENANCE OF TRANSFORMER PROTECTION RELAYS AND
INSTRUMENTATION (P&I)
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF POWER/AUTO TRANSFORMERS PROTECTION RELAYS AND
INSTRUMENTATION (P&I)
Note. The Electromechanical relays have to be checked and tested annually as recommended below,
whereas for the Numerical relays the test schedule should be on 5-10 yearly bases
Description of Inspection Specified Time Period
Remarks/Criteria/Standard/Safety
and Maintenance Work
D/W M3/6 Y1 Y5/10 Precautions
1. Visual inspection (A walk Yes Wear PPE and carry basic tools,
around visual inspection
multi-meter, clip-on-ammeter, etc.
from ground level and
Make entries of the observations in
keeping in view the safe
check sheets/note book.
limits of approach to live
and moving parts to check
apparent
condition,
abnormal noise, rust on body
of the equipment and
component parts, etc.)
2. Differential Protection Yes Should be OK as per specifications
relays
and protection scheme
3. Over Current Protection Yes Should be OK as per specifications
Relays
and protection scheme
4. Earth Fault Protection Yes Should be OK as per specifications
relays
and protection scheme
5. Restricted Earth Fault Yes Should be OK as per specifications
Protection relays
and protection scheme
6.
Over
Excitation Yes Should be OK as per specifications
Protection relays
and protection scheme
7.
Buchholz
Protection Yes Should be OK as per specifications
relays
and protection scheme
8. OLTC Protection relays
Yes Should be OK as per specifications
and protection scheme
9.
Oil
Temperature Yes Should be OK as per specifications
Protection relays
and protection scheme
10. Winding Temperature Yes Should be OK as per specifications
Protection relays
and protection scheme
11.
Rough
Balance Yes Should be OK as per specifications
Protection relay
and protection scheme
12.
HV
Connection Yes Should be OK as per specifications
Protection relay
and protection scheme
13.
LV
Connection Yes Should be OK as per specifications
Protection relay
and protection scheme
50
14.Over Voltage Protection relay
-
Yes
-
Should be OK as per specifications
and protection scheme
51
6.5 MAINTENANCE MISCELLANEOUS PROTECTION RELAYS AND
INSTRUMENTATION (P&I)
SOP CHECK SHEET: MAINTENANCE SCHEDULE AND CHECKS/TESTS
OF MISCELLANEOUS PROTECTION AND INSTRUMENTATION (P&I)
EQUIPMENT
Description of Inspection Specified Time Period
Remarks/Criteria/Standard/Safety
and Maintenance Work
D/W M3/6 Y1 Y5/10 Precautions
1. Visual inspection (A walk Yes Wear PPE and carry basic tools,
around visual inspection
multi-meter, clip-on-ammeter, etc.
from ground level and
Make entries of the observations in
keeping in view the safe
check sheets/note book.
limits of approach to live
and moving parts to check
apparent
condition,
abnormal noise, rust on body
of the equipment and
component parts, etc.)
Miscellaneous Protections
Note. The Electromechanical relays have to be checked and tested annually as recommended below,
whereas for the Numerical relays the test schedule should be on 5-10 yearly bases
1. Bus Bar Protection relays Yes Should be OK as per specifications
and protection scheme
2. Breaker Failure Protection Yes Should be OK as per specifications
relays
and protection scheme
3. DC Supervision relays
Yes Should be OK as per specifications
and protection scheme
4. Trip Coil and Trip Circuit Yes Should be OK as per specifications
Supervision relays
and protection scheme
5. Verification of Cross Trip Yes Should be OK as per specifications
Schemes
and protection scheme
6. Verification of Inter- Yes Should be OK as per specifications
tripping Schemes
and protection scheme
7. Annunciation Devices
Yes Should be OK as per specifications
and protection scheme
8. Metering Devices
Yes Should be OK as per specifications
and protection scheme
9. Auto Re-closing Schemes Yes Should be OK as per specifications
and protection scheme
Shunt Capacitor Bank Protection
Note. The Electromechanical relays have to be checked and tested annually as recommended below,
whereas for the Numerical relays the test schedule should be on 5-10 yearly bases
1. Unbalance Protection Yes Should be OK as per specifications
relays
and protection scheme
52
2. Over Current Protection Yes Should be OK as per specifications
relays
and protection scheme
3. Synchronous Switching Yes Should be OK as per specifications
relay (if provided)
and protection scheme
11kV Feeder Protection
Note. The Electromechanical relays have to be checked and tested annually as recommended below,
whereas for the Numerical relays the test schedule should be on 5-10 yearly bases
1.Over Current Protection
Yes Should be OK as per specifications
and protection scheme
2. Earth Fault Protection
Yes Should be OK as per specifications
and protection scheme
Energy meters
1. Accuracy check and Yes Should be OK as recommended
calibration of Energy meters
at internal metering points in
the same company
2. Accuracy check and Yes Should
be
OK
as
per
calibration of Energy meters
recommendations
of
WPPO
at Cut off points/Common
Department
delivery points
3. Accuracy check and Yes Should
be
OK
as
per
calibration of Energy meters
recommendations
of
WPPO
at IPPs connected with
Department
NTDC/DISCOs
Note. These energy meters
are to accuracy checked at
the
time
of
Annual
Dependable Capacity (ADC)
test
53
7.
MAINTENANCE SCHEDULE AND CHECKS OF TRANSMISSION
LINES
Preventive maintenance is a cycle of planned inspections, work activities and tests to
be implemented to get and ensure for safe and reliable performance of different
equipment and infrastructure components of the grid system. The maintenance cycle
or frequency of implementation is given in terms of time-periods which can be
modified due to weather conditions and constraints of the man-hours and quantity of
the equipment in the jurisdiction of the work crew.
The check sheets given hereunder describe only the maintenance schedules and
checks/tests in terms of what to do and when to do. For the aspect of how to do, one
should consult relevant TSG training course books and/or TSG technical experts. In
addition to the inspection and maintenance activities given in this SOP,
manufacturer’s recommended instructions are also applicable.
The symbols used for time-periods for inspection and maintenance/frequency of
implementation are as under:
D stands for daily,
W stands for weekly,
M stands for monthly,
Y stands for yearly.
54
7.1 MAINTENANCE OF TRANSMISSION LINES
220kV Double Circuit, Twin-bundle Transmission Line
55