Circuit breaker with a digital data processing device

In a circuit breaker ([mu]mC) with a digital data processing device, triggering can be effected on the basis of the direction of an energy flow, that is to say whether energy flows from a current source (Q) to a load (M) or whether energy is conversely transmitted in the opposite direction from the load (M). The direction of the energy flow is derived using an item of information relating to the phase relationship between the AC voltage in the circuit in question and the current flowing in the circuit. In this case, it is possible to use switching elements (10, 12, 14, 16, 18, 20; F1, F2, A; FT, Z1, Z2) which operate in an analog manner and are provided outside the microcontroller. A simple circuit with flip-flops (F1, F2) can be used, for example.