GB945305A - An electric circuit breaker - Google Patents

Abstract

945,305. Arcing preventing in switches. LICENTIA PATENT-VERWALTUNGSG.m.b.H. June 10, 1960 [June 10, 1959], No. 20489/60. Heading H2B. A circuit breaker comprises a bridging contact 6 and fixed contacts 7, 8, connected in parallel with a variable resistance formed by a stationary electrode 12 and a movable cone-shaped electrode 2 immersed in a conducting liquid contained in a metal casing 1 of which electrode 12 is part. The contacts open before the circuit though, the liquid is interrupted and the resistance of the liquid circuit is such that the voltage drop across the contacts on opening is insufficient for arcing to occur, viz. not greater than 10 volts. Compressed air supplied through an opening 13 below a piston 4 on a rod 3 carrying electrode 2 causes the piston to move upwards and contact 6 to be lifted off contacts 7, 8. Cone 2 is raised from its seating against electrode 12 and the electrode gap increases until the cone reaches an upper position and the conducting liquid level has fallen from 11 to 18 with interruption of the liquid circuit. Insulation 16 prevents discharge between the point of the cone and the casing wall, while cooling ribs 17 prevent excessive heating of the liquid. The resistance of the liquid is increased as electrodes 2, 12 separate, by gradually replacing the liquid, e.g. salt solution, with distilled water, oil, hexane or other insulating liquid. Compressed air enters through opening 14 to reclose the breaker. The contacts are metal or carbon, and a plurality of such contact arrangements may be connected in series.