GB347007A - - Google Patents

Abstract

347,007. Automatic circuit-breakers. ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Bush House, Aldwych, London.-(Assignees of Slepian, J. ; 1115, Lancaster Street, Pittsburg, U.S.A.) April 28, 1930, No. 13019. Convention date, April 27, 1929. [Class 38 (v).] Electromagnetic switches; impact switches; magnetic blow-outs.-Relates to switches wherein the initial separation of the contacts takes place at a high rate of acceleration under the action of mechanism that is first accelerated and then applies an impulse to separate the contacts. The latter, if of copper, are preferably arranged to be separated <1>/32 of an inch in 0À001 seconds or less, so that a magnetic blow-out can move the arc before the contacts reach a temperature high enough to cause extensive vaporization. In Fig. 1, a spring 14 acting on an abutment 13 urges a movable contact 3 to bridge arc members 4, 5. Energization of a solenoid 15 moves a roller 16 so that a lever 6, pivoted at 7, is urged by a spring 8 to apply an impulse to the abutment 13 and move the contact 3 from the member 4 at high speed. The effect may be modified by arranging for the member 3 to slide on the member 4 before leaving it, thus allowing a smaller acceleration of the former. In a modification (Fig. 3, not shown), the member 5 is also arranged to move away from the member 4 a short distance against the action of a spring, and is connected to the right-hand abutment of spring 14 so as to be moved when the latter is sufficiently compressed by the impact. Fig. 7 shows a commercial form in which an electromagnet 24 holds one end of an armature 22, which is pivoted at 23 and connected by a tension spring 20 with a fixed abutment and by a second spring 28 with a movable contact-arm 26 pivoted at 27. On de-energization of the magnet 24, both springs act on the armature until a hammer 25 thereon strikes the arm 26 to drive it from the fixed contact, the spring 20 alone completing the opening movement. The strength of the blow-out field may be one-half a gauss per ampere of current.