Selective trip unit for a multipole circuit breaker

摘要

A selective magnetic trip unit comprises a fixed magnetic armature located facing a movable magnetic armature and a damping device with a blade mounted on the movable magnetic armature. The damping device is designed to be in an inactive state up to an intermediate non-tripping position when the movable magnetic armature is attracted by polar parts of the fixed magnetic armature during a first travel, switching to the active state resulting from a deformation of the damping device during a second travel of the movable armature between the intermediate position and the final attraction position causing tripping of the circuit breaker.