Selective main circuit breaker has two switching contacts with closing mechanism with control handle movable from starting position through pass to end position to ensure first contact closes before second

摘要

The circuit breaker has two switching contacts wherein a closing mechanism ensures that the first contact is closed before the second contact. The closing mechanism has a handle (14) for controlling the switching contacts and a locking member (26). The handle is movable from a starting position in which both contacts are open into a pass position in which the first contact closes but the locking member prevents the second contact from closing. The handle is then movable into an end position where the second contact can be closed in the absence of any short circuit current. If a damped short circuit current flows through a bypass after reaching the pass position an otherwise mechanically rigid connection from the handle to the second contact yields through releasing a catch through a bimetal element for example so that the second contact can no longer close when the handle reaches the end position.