GB249870A - Improvements in or relating to arc-rupturing devices for electric circuit-interrupting apparatus - Google Patents

Abstract

249,870. Metropolitan-Vickers Elec-. trical Co., Ltd., (Assignees of Austin, B. 0.). March 26, 1925, [Convention date]. Sparking, preventing.-A heavy current circuitinterrupter is provided with a magnetic blow-outconsisting of arcing tips 25, 26 and 36, 37 of U- form, one limb serving as the arcing tip proper and the other limb serving to conduct the current to the tips and to the fixed and movable contacts 27, 43 which are in metallic connection with the tips. The switch shown is pneumatically operated, and when the pressure is removed the piston 34 falls carrying with it the movable contact 43 and the lower arcing tip &c. connected with it. As the main contacts separate, their inner ends incline towards one another under the action of the spring 44 as shown, so that the arc forms at the inner ends. The upper U-shaped arc-tip encloses a magnetic core 28 which has extended polepieces 30 located outside an arc chute 45. The pole-pieces 30 support further pole-pieces 40 extending to the neighbourhood of a second magnetic core located in the lower U-shaped horn. The blow-out field thus produced draws the arc from the contacts on to the arc tips and as, under the magnetic influence, the arc is lengthened, the current path includes a greater length of the U- shaped tips and, consequently has a greater magnetic action producing a greater blow-out action.