Arc control for load-break switches

Claim 1

A load break switch for service entrance and like applications in which the switch may be opened or closed under fault conditions, comprising: a first fixed contact and a second fixed contact mounted on a base in spaced relation to each other; a movable contact, comprising two parallel blades each having one end pivotally mounted on said first fixed contact and movable along a given path between an open position displaced from said second movable contact and a closed position in which inner surfaces of the other ends of the blades engage substantial areas of the opposed sides of said second fixed contact; a first arcing contact mounted on the outer side surface of one blade of said movable contact; a second arcing contact, fixedly mounted at one side of said path, adjacent to but spaced from and electrically connected to said second fixed contact, said second arcing contact being aligned with said first arcing contact and engageable therewith during opening and closing movements of said movable contact; an arc chute comprising: a frame, formed of a material which releases a deionizing gas in the presence of an arc, encompassing three sides of said path immediately adjacent said second arcing contact, said frame projecting beyond said path, on said one side, to a greater width than said arcing contacts, a plurality of grid plates, mounted in and extending across said frame and forming a plurality of arc-dividing chambers each extending across the entire width of said path, each grid plate having an asymmetrical opening in its forward edge to permit passage of the ends of said movable contact blades therethrough, each said opening including a notch extension, at said one side of said path, aligned with said arcing contacts.