Circuit breaker having contacts with erosion-resistant covering

Abstract

A circuit breaker includes a cylindrical arcing chamber filled with an insulating medium. The arcing chamber has a power current path and an insulating housing. The insulating housing has a longitudinal axis and the power current path extends along the longitudinal axis of the insulating housing. The power current path includes a fixed contact arrangement and a contact arrangement. The fixed contact arrangement is attached to an electrically insulating guide part. The contact arrangement has a moving contact cage. The fixed contact arrangement and the contact arrangement have a first and second fixed erosion-resistant covering, respectively. The insulating housing has a blast volume for accumulating an increased pressure of the insulating medium which occurs when the moving contact cage breaks contact with the fixed contact arrangement. When the circuit breaker is in an on position, the contact cage contacts the fixed contact arrangement above the guide part and surrounds the guide part. The insulating housing has a shoulder which projects into a region between the first erosion-resistant covering and the second erosion-resistant covering. The first and second erosion-resistant coverings are arranged concentrically around the guide part and the moving contact cage. When the circuit breaker switches from the on position to an off position, the moving contact cage moves out of contact with the fixed contact arrangement and into contact with the guide part.

Dependencies are inferred from the claim text.