Circuit Breaker Unit

The disclosure relates to a circuit breaker unit having a circuit breaker for connection of at least two electrical networks. The circuit breaker unit has a control unit for monitoring voltages of the networks and/or at least one current through the circuit breaker. In the event of one of the fault scenarios, overvoltage or undervoltage in one of the networks or overcurrent across the circuit breaker, the controller separates the two networks from one another. The circuit breaker includes at least one controllable first resistor, a controllable second resistor, and a controllable third resistor. The control unit is configured, in the event of a fault scenario in one of the networks, to adjust the values of the resistors so that the networks are separated from one another and so that the voltage in the fault-free network remains within predefined limits.