GB514704A - Improvements in or relating to electric liquid-break circuit breakers - Google Patents

Abstract

514,704. Liquid-blast switches. GENERAL ELECTRIC CO., Ltd., and GARRARD, C. J. O. May 13, 1938, No. 14322. [Class 38 (v)] In a circuit-breaker of the liquid-break type, upon movement at break of a contact away from a complementary contact, liquid contained in the first contact or an extension thereof is arranged to be injected positively into the space vacated by the contact, the volume of liquid injected into the said space being substantially equal to the volume of the space. An earthed plate 5 supports an insulating cylinder 4 which is filled nearly to the plate 5 with oil and is provided with a bottom closure 15 having a drainage hole and carrying a fixed butt contact 18 which is slightly offset from the centre of closure 15. Cylinder 4 is lined with an arcresisting cylinder 19 below which is a similar cylinder 20, which in turn is lined with insulating cylinders 21, 22 and contain an arc-control device (not shown). A frusto-conical part 25 of a metal cylinder carries a circular metal plate 26, an aperture in which is covered by a flanged sleeve-like member 28 supporting a condenser bushing 29, the lower end of which carries a protecting insulator 34. The hollow movable contact unit 3 comprises the contact proper 38, the extension 39, and parts 40, 41 capable of relative movement, the whole being guided by a metal sleeve 36 in the base of a metal cylinder 35 fixed within the bushing 29. The cylinder 35 also carries a cross bar 43 which engages in slots 42 in the part 40 and supports a fixed piston 44. The length of part 41 is about half that of the unslotted part of 40, and a compression spring 47 acts between its upper end and a flange 48 at the top of the unslotted part of 40, the spring being enclosed within a cylinder 49 fixed to the top of the part 41 and having a stop 50 for limiting the movement between 40, 41. A second spring 37, which is stronger than 47, acts between the guide 36 and a flange 51 on the cylinder 49. To open circuit, the part 40 is moved upwardly, aided by spring 37, and as the contacts separate, relative movement between 44 and 40 forces oil through the extension 39 into the space vacated by the contact, the volume of liquid transferred being substantially equal to that of the space. When cylinder 49 reaches the cross bar, the part 41 is arrested, but the part 40 continues to move, aided by the spring 47. The reverse operation occurs in switching on again. The arrangement is applicable also to downwardly or horizontally-movable contacts.