Circuit breakers are used as switching and protection devices in electrical circuits, particularly in multi-phase power systems. In particular, they are applied in low-voltage networks, i.e. power systems with voltages of up to 1000 V alternating voltage or 1500 volt direct voltage. In particular, circuit breakers and switch currents from 63 amperes or 100 amperes or for currents of up to 1000 amperes, 6300 amperes or 10 000 amperes.
Circuit breakers measure the electric current in the electrical circuit and interrupt the circuit when current limit values are exceeded which occur, for example, in the case of overload or short circuit in the electrical circuit.
To measure the electric current in the conductors, coils are frequently used. In particular, Rogowski coils are widely applied. They are also called Rogowski transducers or Rogowski transformers.
If the measuring unit for measuring the electrical current in a circuit breaker fails, the protective function in the electrical circuit is no longer guaranteed since overloads and short circuits can no longer be determined.