Patent ID: 8810985

Claim:
A hybrid circuit breaker for interrupting a fault current in an electrical circuit line having a line impedance, the hybrid circuit breaker comprising a mechanical circuit breaker adapted to interrupt the line upon detecting the fault current, and a semiconductor device arranged in parallel with the mechanical circuit breaker to conduct the fault current when the mechanical circuit breaker is disconnected, characterized in that the hybrid circuit breaker further comprises a branch connected between the electrical circuit line and ground, the branch including a variable impedance unit, and a control unit configured, upon detecting the fault current, to adjust the impedance value of the variable impedance unit, and to connect the variable impedance unit in parallel with the line impedance wherein the control unit is further configured, upon detecting the fault current, to determine an impedance value of the variable impedance unit so that the magnitude of the fault current increases to a pre-set value in a fixed time and to adjust the impedance value of the variable impedance unit to the determined impedance value.