Generator
MCCB Trips Randomly Under Normal Load
Symptoms
Circuit breaker trips without apparent overload condition.
Likely Cause
Loose terminals, overheating, defective MCCB mechanism, harmonic currents, or incorrect protection settings.
Testing Procedure
1) Measure load current. 2) Inspect terminals for heating. 3) Check thermal settings. 4) Verify breaker condition.
Tools Required
Clamp meter, thermal camera, screwdriver set
Safety Precautions
Isolate circuit before opening panel covers.
Step-by-Step Solution
1. Tighten connections. 2. Replace damaged MCCB. 3. Adjust protection settings. 4. Balance load across phases.
Prevention
Conduct annual thermographic inspections.
Engineering Notes
Loose connections are a leading cause of nuisance breaker trips.