GB384116A - Improvements in and relating to oil switches - Google Patents

Abstract

384,116. High-tension switches. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Soc. GÚnÚrale de Constructions Electriques et MÚcaniques (Alsthom) ; 146, Avenue des Champs Elysees, Paris.) Jan. 22, 1932, No. 2068. Convention date, Jan. 22, 1931. [Class 38 (v).] In a liquid-break switch the movable contact 3 is mounted on the operating rod 8 immediately below a piston 2 which fits loosely within an insulating cylinder 1. When the contacts are in engagement the insulating liquid is arranged to extend to a height x, x immediately below the surface of the piston 2, the liquid level being maintained by a float or " birdfountain " apparatus communicating with the lower end of the switch cylinder through a non-return valve 10. Immediately the switch contacts are separated, the sudden rise in pressure produced by the vapour formed by the arc causes an acceleration of the movement of the contact 3, this acceleration continuing until the piston uncovers ports 7 formed in the side of the cylinder 1 and the vapour discharges. The movement of the contact is cushioned by the dashpot action of the air in the cylinder above the ports 7, the cushioning effect being assisted by a gland 12 around the rod which also prevents the escape of the arc gases around the rod and prevents their corrosive action on the portion of the rod which is surrounded by a spring contact assembly 11 bv which current is conducted to the movable contact. The loose fit of the piston 2 within the cylinder 1 permits the switch to be closed without appreciable retardation. The opening movement of the switch is initiated by the action of a spring which is under the control of latching mechanism. Specification 362,417 is referred to.