Can someone please clarify something to me about large electric motor protection
&quot;DC overcurrent tripping devices on the breaker&quot; refers to a DC operated coil in the circuit breaker that allows an external device to trip the circuit breaker. The external device is the &quot;thermal or dashpot&quot; device that monitors the stator current and supplies the DC voltage to trip the breaker. The motor could be any type of large motor, but since &quot;stator faults&quot; are mentioned an AC motor must be the type in this case, because the stator of a DC motor carries the field current rather than the motor load current.
For fail-safe operation, the coil in the breaker should be energized for normal operation and de-energized for trip.