State monitoring device for circuit breaker

摘要

Astatemonitoring device for a circuit breaker is provided. When a movable contact is opened by electromagnetic repulsive force, in other words, when passed current attains a level at which the circuit breaker is allowed to carry out tripping operation but the operation of an opening/closing mechanism is still not carried out, the device can inform about the state. The device includes comparison means for comparing the value of passed current obtained from a current detector and a reference current value at which the opening operation of a movable contact is started by electromagnetic repulsive force generated between a fixed contact and the movable contact forming a main contact and generating an output if the value of the passed current is at least the reference current value, and warning signal output means for outputting a warning signal if the value of the passed current reaches a level at which the circuit breaker is allowed to carry out tripping operation and a signal obtained from an auxiliary switch continues to indicate the closed state of the main contact based on the output signal of the comparison means and the signal from the auxiliary switch that detects the opened/closed state of the main contact.