Abstract: A residual current device includes a first delayed-tripping fault-current tripping circuit for alternating and pulsed fault current, and a second fault-current tripping circuit for direct fault current, which are connected in parallel with one another to a control line of a release for a circuit breaker, with first decoupling circuit being provided for electronic decoupling of the first fault-current tripping circuit from the control line.

Abstract: A differential current circuit breaker is disclosed in operation with a transductor circuit. The transformer has a secondary winding which is coupled to a measuring resistor in series with a generator, in particular a square wave generator, for alternating magnetization. The circuit breaker includes an evaluation circuit coupled to a tripping mechanism that acts through a breaker mechanism on switching contacts in the conductors being monitored. The evaluation circuit is coupled to a tap between the secondary winding and the measuring impedance. The generator capable of setting the generator frequency within a larger frequency range than is required to compensate for tolerance adjustment in the generator itself.

Abstract: A differential current protection circuit breaker that operates as a magnetic amplifier has a secondary winding connected in series to a complex, predominately capacitive measuring impedance and a square wave generator. An evaluating circuit is connected at a tap and is actuated along a tripping device and a switch latch of a switching contact device. The evaluation circuit is blocked by a sensor that responds to extraneous current surges or voltage surges during a predetermined response time. A blocking device in the tripping device responds to the signals from the sensor.