Auxiliary contact circuit breaker actuated by principal contacts - uses two physically separate contacts, electrically in parallel, with auxiliary trip initiated by opening of principal contacts

摘要

The circuit breaker has auxiliary contacts which are electrically in parallel with the main contacts but physically separate. The main contacts open before the auxiliary contacts, both contacts being operated by separate fast-acting trip mechanisms. The trip mechanisms are spring operated, over-centre, mechanisms, the springs being pre-tensioned by the closing of the switch. The two sets of contacts, main and auxiliary, are placed physically side by side so concentric shafts may be used. The trip contact operates firstly the principal contact mechanism and the opening of the principal contacts actuates the trip relay of the auxiliary contact trip mechanism. Since the auxiliary contacts are last to open they draw the main arc and arc chutes provided to assist arc extinction.