Circuit Breaker trip caused by utility fault?
Circuit Breaker trip caused by utility fault?
(OP)
A commercial building is supplied through a 630amp 415v circuit breaker. On two occasions this circuit breaker has tripped (overcurrent or short circuit) after utility faults have occurred nearby. One of the faults was caused by a vehicle hitting a power pole, I'm not sure about the other one.
The circuit breaker does not have any shunt trip or under-voltage releases fitted.
What would cause this circuit breaker to trip?
The circuit breaker does not have any shunt trip or under-voltage releases fitted.
What would cause this circuit breaker to trip?






RE: Circuit Breaker trip caused by utility fault?
RE: Circuit Breaker trip caused by utility fault?
1) A lost phase. This can cause the current to spike in other phases. Your breaker could notice a ground fault problem.
2) Large spikes from motors losing power very briefly.
3) Low voltage causing motors to draw excessive current.
4) ?? What else guys?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Circuit Breaker trip caused by utility fault?
RE: Circuit Breaker trip caused by utility fault?
"4) The motors on your system may be supplying fault current to the fault on the utility system. During the first few cycles of the fault this could be close to the DOL starting current of the motors."..you're on the right track! COnsidering, you have a large machines this will contribute about 30% reactance to the fault.
If you need to be isolated during FAULTS, why not used directional overcurrent relay?