GB353997A - Improvements in and relating to pressure relief devices for electric switches of thefluid break type - Google Patents

Abstract

353,997. Transformer casings. BRITISH THOMSON.HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Hilliard, J. D. ; Hotel Hough, Schenectady, New York, U.S.A.) June 10, 1930, No. 17825. Convention date, June 10, 1929. Addition to 293,776, [Class 38 (v), Electric switches &c.]. [Class 38 (ii).] Relates to pressure relieving devices for switches of the fluid-break type wherein a venting chamber 7 communicating with the container 1 is normally closed by a circular bowed plate (or by a pair of such plates) which are blown out if high pressure is developed when, for example, the switch is opened on short circuit, as described in the parent Specifica. tion. The invention consists in combining with the bowed plate or plates means whereby the disruption of the plates closes or opens a signalling or tripping circuit. The bowed plates 14, 15 are mounted between opposite sides of a flange on a sleeve 11 which is secured in the orifice between the container and the venting chamber and they are held in place by a central bolt 16. A frangible rod 18 of glass bridges the orifice and is removably mounted in a gas-tight manner in the member 11. A projecting end of the rod normally holds a spring contact 20 clear of a companion contact 24 but when one of the bowed plates is expelled the rod is broken, the circuit at 22, 24 closed and an alarm given. In a modification (Fig. 4, not shown) the glass rod is replaced by a wire similar to a fuse wire supported in a glass tube and forming part of the maintaining circuit of a relay so that when the wire is broken an alarm is given. The Specification as open to inspection under Sect. 91 (3) (a) states that the invention is applicable also to transformers. This subject-matter does not appear in the Specification as accepted.