An overtrip happens when a protective device activates too sensitively or without proper time coordination, clearing a fault that should have been handled by a different device further downstream. This results in unnecessary power outages for healthy parts of the network. It usually points to incorrect relay settings, bad CT ratios, or a failure in protection coordination schemes.
We had an overtrip on the main incoming feeder because the time delay was set shorter than the branch breaker.
Related terms
Nuisance trip
Protective device opening with no real fault present, usually from bad settings, leakage or transients.
Selectivity
Arranging protection so only the device nearest a fault operates and the rest of the system stays in service.
Protection relay
Device that watches currents and voltages and orders a circuit breaker to trip when it detects a fault.