Circuit breaker device and method

A circuit breaker device for protecting an electrical low-voltage circuit, the circuit breaker device comprising:

• a housing having network-side and load-side connections for conductors of the low-voltage circuit;
• a voltage sensor unit for determining a voltage level of the low-voltage circuit;
• a current sensor unit for determining a current level of the low-voltage circuit;
• a mechanical isolating contact unit having contacts configured to be switched open to avoid a current flow or switched closed to allow a current flow in the low-voltage circuit;
• an electronic interruption unit connected in series with said mechanical isolating contact unit on a circuit side, said electronic interruption unit configured to be switched by semiconductor-based switching elements to a high-impedance state of said switching elements to avoid the current flow or a low-impedance state of said switching elements to allow the current flow in the low-voltage circuit;
• a control unit connected to said voltage sensor unit, to said current sensor unit, to said mechanical isolating contact unit and to said electronic interruption unit for initiating avoidance of the current flow in the low-voltage circuit upon exceeding at least one of current limit values or current-time limit values;
• upon said contacts being closed and said electronic interruption unit having a low impedance, said electronic interruption unit having a high impedance upon occurrence of a voltage-reduced state of the low-voltage circuit;
• and
• after leaving the voltage-reduced state, said electronic interruption unit having a low impedance again.