Selective isolating circuit breaker system for several loads - has bimetal thermal element in parallel with main switch and controlling switch lock

摘要

The system has power circuit breakers associated with each load, having a first tripping characteristic. In front of the breakers is slide-connected a main circuit breaker with a second tripping characteristic, which has a thermal bimetal element in parallel. When a short circuit occurs the current is switched by a change-over device at least partly through this thermal element, which controls the position of an intermediate lever such that the latter moves into the path of an armature, moving with the contact lever and into the region of the switch lock. Thus when the armature is operated, the switch lock is released by the armature via the intermediate lever. The change-over device is preferably controlled by the movement of the contact lever. The change-over switching may be carried out on breaking. A PTC current-dependent resistor may be in series with the bimetal element.