Method for monitoring operability of circuit-breaker, involves determining variable depending on potential at contact point between coil and resistance element, and evaluating determined variable

摘要

The method involves applying voltage at a series connection from a coil (S) and a resistance element (R1) without interrupting the flow of electric current in an electric circuit. A variable is determined depending on the potential at a contact point (P1) between the coil and the resistance element. The determined variable is evaluated. An error free condition is accepted, when the lies in a value interval. A signal is sent to activate an unit, when the variable value lies in another value interval. An independent claim is also included for a circuit-breaker comprising a coil.