Patent ID: 8624694

Claim:
A residual-current circuit breaker comprising: at least one core-balance transformer configured to have a first conductor and a second conductor of an electrical supply system which is to be protected routed therethrough; at least one secondary winding arranged on the core-balance current transformer, the secondary winding being connected to a release by circuitry; a test circuit connecting the first conductor and the second conductor, the test circuit having at least a first test resistor and a reset button, wherein, so as to provide accurate checking of an ability of residual current tripping to function, the test circuit includes a second test resistor arranged in series with the first test resistor by circuitry, the second test resistor being bridged by a bypass line, the bypass line being routed through the core-balance transformer, and at least one first voltage dependent resistor being arranged in the bypass line by circuitry.