Electrical apparatus including interlocking circuit for short- time delay and long-time delay tripping

摘要

A circuit breaker of the type having short delay and long delay tripping modules. Separate signals are provided as external outputs from the latter modules. Furthermore, inputs are provided to the latter modules for disabling the normal operation thereof. The above-mentioned breaker also includes an instantaneous tripping circuit. If the amount of overload current is sufficiently high, an instantaneous tripping operation takes place. If the overload current is relatively lower than that which would necessitate instantaneous tripping, short delay or long delay tripping will take place. If the current then continues to increase to a sufficiently high value, the circuit breaker will operate through the instantaneous tripping circuit. One of the above-mentioned circuit breaker apparatus can be interconnected with others so that one circuit breaker in an electrical line to be protected will open and provide output signals which will prevent the short delay and long delay of other circuit breakers in the system from operating thus saving some of the protected system from shut-down.