GB193490A - Improvements in and relating to electric switches - Google Patents

Abstract

193,490. British Thomson-Houston Co., Ltd., (General Electric Co.). Nov. 23, 1921. Oil-break switches have an outer vessel 10 containing oil from the insulating cover 12 of which is suspended a pressure accumulating chamber 15 in which the circuit is broken. The inner chamber 15 is built up from a cylindrical metal wall 19 with top and bottom plates, the top plate 16 of insulating material and the bottom plate 18 of conducting material being held together by a number of bolts 25. The chamber thus formed is suspended from the cover 12 by insulated bolts 14 at least one of which conveys the current to the lower plate 18. Centrally secured to the lower side of the plate 18 is an annular conducting member 27 carrying segmental contacts 29 connected thereto by flexible leads 31 and provided with springs 32<1> through which projects the rod 32 which forms the movable contact member. On the upper face of the member 27 is supported an annular conducting member 35 fitting in a central shoulder perforation 34 of the plate 18, the member 35 having an airing surface 36 arranged above the upper contact surface of the contacts 29 and separated from 18 by a ring shaped insulator 30. When the circuit is broken by upward motion of the rod 32, an arc is struck between its end and the contacts 29 which is immediately transferred to the arcing surface 36. The rise of pressure within the inner chamber forces a stream of oil across the arc which is prevented from moving to the upper surface of the plate 18 by a sheet 40 of insulating material. As the movable contact member 32 leaves the upper orifice of the pressure chamber it passes through a passage 51 in the insulator 43 carried by the plate 16, and if the arc still persists a second blast of oil will be directed from the chamber up through this passage and into the path of the arc. The material ejected at the upper orifice is directed by a tube 45 against an insulating baffle plate 46, openings 50 in the cover plate 12 being provided to allow the arc gases to escape. In an alternative construction the lower end of the member 27 may he closed, and lateral openings provided therein for the ejection of the arc gases. An insulating sleeve 41 surrounds the chamber 15.