Abstract: The trip device with an electronic processing unit which gives a tripping order in terms of the rms value of the current measured by current transformers and of the threshold and time delay setpoints. The non-linearity of response of the current transformers is corrected by a device which modifies the current, threshold, or time delay values. These corrected values enable precise trippings to be achieved in compliance with the values of the current flowing in the circuit breaker. The type of correction is adapted to the circuit breaker rating by parameters obtained by tests and previously stored in a device.

Abstract: The electronic trip device comprises a device for selecting the faults which are to bring about locking of the circuit breaker contacts in the open position. When a fault in the power supply system protected by the circuit breaker leads to a trip, the trip device orders locking if this fault is one of the faults selected by the selection device.