Circuit Breaker Maintenance Checklist

Circuit Breaker Maintenance Checklist



1. Safety Precautions

  • Apply LOTO (Lockout-Tagout) before work.
  • Discharge stored energy (springs, capacitors).
  • Use proper PPE: arc-flash suit, insulated gloves, face shield.
  • Verify breaker is isolated, earthed, and tagged.

2. Visual Inspection

  • Check breaker housing for dust, cracks, corrosion, or oil leaks.
  • Inspect breaker mechanism for damage or deformation.
  • Ensure breaker position indicators (ON/OFF/TRIPPED) are working.
  • Verify nameplate data matches circuit application.

3. Mechanical Checks

  • Operate breaker manually – check smooth ON/OFF/trip operation.
  • Inspect operating springs, levers, and linkages.
  • Check interlocks (mechanical/electrical) for correct function.
  • Lubricate moving parts as per OEM instructions.
  • Verify alignment of contacts and moving arms.

4. Electrical Checks

  • Measure contact resistance with micro-ohmmeter.
  • Check insulation resistance (IR test) phase-to-phase and phase-to-earth.
  • Perform dielectric withstand test (for MV/HV breakers).
  • Inspect secondary/control wiring connections.
  • Verify breaker closing and tripping coil resistance.

5. Protection & Control

  • Test trip unit/relay calibration settings (overload, short-circuit, earth fault).
  • Verify protection relay functional trip test.
  • Check auxiliary contacts (NO/NC) for continuity.
  • Test remote/local operation commands.
  • Confirm emergency trip button functionality.

6. Contact System

  • Inspect main contacts for wear, erosion, or pitting.
  • Clean carbon deposits from contacts (if applicable).
  • Check arcing contacts & arc chute condition.
  • Verify contact alignment and wipe.

7. Specific Breaker Types

  • ACB/MCCB

  • Inspect draw-out mechanism (racking in/out).
  • Test spring charging motor (if motorized).
  • VCB (Vacuum)
  • Check vacuum bottles for leakage.
  • Perform vacuum integrity test.
  • SF6 CB
  • Check SF6 gas pressure, density, and alarms.
  • Inspect gas leakage seals.
  • GIS
  • Verify gas compartment tightness.
  • Inspect partial discharge monitoring system.

8. Functional & Operational Tests

  • Trip breaker with relay test kit.
  • Close breaker on no-load to check mechanism response.
  • Verify breaker closing/tripping time with timer.
  • Perform secondary injection test of protection relay.
  • Conduct thermography for hot spots in terminals.

9. Maintenance Frequency

  • Monthly: Visual inspection, trip coil test, mechanical operation.
  • Quarterly: IR test, contact wear check, lubrication.
  • Yearly: Full inspection + functional testing, contact resistance, relay testing.
  • Every 3–5 Years: Major overhaul (depending on OEM and duty cycle).

10. Documentation

  • Record breaker operating hours and number of operations.
  • Maintain a log of test results (IR, contact resistance, coil resistance).
  • Note defects, repairs, and parts replaced.
  • Sign off by technician and supervisor.

✅ Pro Tip: Always keep spare trip coils, auxiliary contacts, and arc chutes for critical breakers.

Would you like me to create this checklist in a ready-to-use Excel/Word format with columns (Item, Frequency, Check, Remarks, Done By, Date) so you can directly use it for maintenance records?

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