| 摘要 |
PURPOSE:To take the protection coordination of a host circuit breaker and a subordinate circuit breaker positively by executing release operation while using the no-transmission of a release completion signal for a fixed time from the subordinate breaker as conditions when the necessity of release operation of the host circuit breaker is decided. CONSTITUTION:When overload or a short-circuit accident is generated in an AC motor 24, overcurrents are detected by a host circuit breaker 1, the necessity of release operation is decided, and the release operation of a subordinate circuit breaker 17 is stood by without conducting release operation only for a fixed time 'T'. When release operation is not performed for some reason by the subordinate circuit breaker 17, a micro-computer 13 outputs an output signal at a high level 'H' from an output port P after the fixed time 'T' passes. Accordingly, a thyristor 15 is turned ON, electricity is conducted through a tripper 14, thus release-operating main circuit contacts 4A or 4C, then detaching the AC motor 24 from a three-phase AC power line 16A or 16C. |
