ABB-Substation-Condition-Monitoring-Schedule(7)

1. TRANSFORMER

2. CIRCUIT BREAKERS (SF6 & AIR BLAST)

PSST&DSSDepartment:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION MONITORINGPrepared: Reviewed: Status: Date: Language:

Page 9 of 16Revision:

AG

NJ

Draft

09/05/25

en

NIL

1 2 3 4 5 6

Check for any gas/ air leakage Check for proper gas/ air pressure Check for any hot spots at any terminals Checking of oil leaks from grading capacitors Checking of air compressor for oil level, oil quality, air filter, V-belt tension Check for crack in insulators

M M M M QY M

B) Maintenance Schedule Sr.No. Details 1 Check tightness of all clamps and connectors/ 2 3 4 5 6 7 8 9 terminals Check for damage paint condition and corrosion Replaced damaged bushings Checking of all interlocks Checking of pressure settings Cleaning of breaker interrupter, support insulators, PIRs and grading capacitors Checking of Close/ trip coil currents Checking of healthiness of operation counter Control cabinet (i) Checking of tightness of all cable termination in MB (ii) Checking of door sealing gaskets and replacement, if necessary (iii) Repainting of metallic surfaces (iv) Checking of space heaters Checking of tightness of foundation bolts Maintenance of air dryers in Air blast circuit breakers Functional checking of auto starting of air compressors and dryers Checking of air pressure drop during duty cycle operation Overhauling of compressors Maintenance of air dryer if provided Frequency Y Y SOS Y Y Y Y Y Y Y SOS Y Y½Y Y Y SOS½Y

10 11 12 13 14 15

PSST&DSSDepartment:

GUIDELINE FOR SUBSTATIONS SERVICE INSPECTION AND CONDITION

MONITORINGPrepared: Reviewed: Status: Date: Language:

Page 10 of 16Revision:

AG

NJ

Draft

09/05/25

en

NIL

16

Spring operated mechanism (i) Oil leakages from close and open dashpots, replace the same if leakage observed (ii) Greasing/ lubrication of gears and various latches in the operating mechanism (iii) Checking of play of gaps in catch gears (iv) Maintenance of spring charging motors, cleaning of carbon brushes and contactors (v) Replacement of oil in dashpots Checking of pole discrepancy relay Functional checks, duty cycle operation including rapid re-closing (O-0.3s-CO) Checking of air pressure drop during duty cycle operation Checking of all operational lock-outs including SF6 density monitor Checking tightness of earthing connections Cleaning of auxiliary switch contacts with CTC Checking of local ON/OFF indicating lamps in breaker, if provided Check interlocking of isolators with breaker After maintenance trip the breaker through backup

Y Y Y Y SOS Y Y U Y Y Y Y Y Y

17 18 19 20 21 22 23 24 25

C) Condition Monitoring (Condition based Maintenance) Sr.No. 1 2 3 Details CB operating timings (Main, PIR, Aux.) Static contact resistance measurement Dynamic contact resistance measurement (DCRM), contact travel, contact speed, contact wipe, arcing 4 5 contact length Capacitance and tanδ measurement of grading capacitors Dew point measurement of SF6 gas 4Y 3Y Frequency Y 2Y 2Y

3. CURRENT TRANSFORMER

schedule

4. POTENTIAL TRANSFORMERS/ CAPACITANCE VOLTAGE TRANSFORMERS/ COUPLING CAPACITORS

schedule. This test is not possible to be conducted at site if isolation of neutral of intermediate PT is not possible at site.5. DISCONNECTORS AND EARTH SWITCHES

6. SURGE ARRESTERS

7. WAVE TRAPS

M- Monthly, QY-quarterly, Y-yearly, 2Y-once in 2 years, 3Y-once in three years, 4Y- once in 4 years, SOS-as and when required.

3) CONCLUSION

The fundamental goal of inspection, maintenance and condition monitoring of substation is to preserve the function or operation of a system. Specifically, the function that has to be preserved for electric substations is the delivery of safe, reliable electric power to customers

4) BIBLIOGRAPHY

1. Manual on EHV Substation Equipment maintenance

2. EPRI- Inspection and Maintenance Guidelines for Distribution substation3. Design Guide for Rural substations-USDA