Low voltage circuit-breaker with improved breaking

Abstract From the Canadian patent

A moulded case low voltage circuit breaker for high currents has no arcing contacts and is equipped with arc blow-out means drawing the arc very quickly away from the contacts. An insulating shield associated with the moving contact forms an arc formation chamber of a small volume which is open in the direction of the arc chute. The moving and stationary contacts are fitted with arcing horns constituting a small divergent path in proximity to the contacts favouring rapid displacement of the arc, this divergent path leading to an area defined by a hump of the horn. In this area, the clearance of the arcing horns is smaller than the clearance between the contacts as soon as the latter …