Pre-Planned Preventive Maintenance of Air Circuit Breaker (ACB)

The points which needs to be focused for the maintenance of the Air Circuit Breakers. Also if your ACBs are under AMC then these are the points which needs to be ensured for the proper preventive maintenance of the same.

• Cleaning of breaker with CRC-2-26
• Removal of old grease and re-greasing the same with recommended grease.
• Check condition of arcing contact and gap between fixed and moving arcing contacts shall be checked.
• Checking the reset mechanism, tripping of breaker through push button
• Checking tripping of ACB through protection release
• Tripping of ACB manually through volt metric release.
• Checking and adjust freeness of DN and volt metric release trip rod
• Checking presence and proper tightening of hardware.
• Checking presence of all cir clips
• Checking condition and alignment of jaw contact with cradle terminals
• Checking condition of ACB wiring and replace if required
• Checking and adjusting gap between hylam sheet and side plate
• Checking proper closing of all poles together
• Checking working of anti pumping device in case of EDO ACB
• Checking alignment of SIC and it’s operation
• Checking condition of arc chutes
• Checking ACB tripping through shunt release
• Checking motor operation in case of EDO ACB
• Checking closing coil operation in case of EDO ACB
• Checking  continuity and proper changeover of aux contact block
• Checking of release by secondary injection for O/L, S/C, E/F
• Setting of release as per the load
• Checking the healthiness of CTs.
• Cleaning & checking of tightness of wires on terminal block.
• Insulation Resistance Testing.
• Contact Resistance Testing.
• Final testing of the circuit breaker by switching it ON/OFF both Mechanically as well as electrically