Earth leakage circuit breaker for use in distributed system, has active filter circuit with operational amplifier, where circuit is provided with analog circuit and switched from low pass filter circuit to band pass filter circuit

摘要

The breaker has a filter-and booster assembly (10) provided between a secondary winding of a summation-current transformer (3) and an error current collecting circuit (4). The assembly has an active filter circuit with an operational amplifier that is provided as an amplifier unit with externally added passive filter units. The active filter circuit is provided with an analog circuit and switched from a low pass filter circuit to a band pass filter circuit.