GB486050A - Improvements in or relating to fluid-blast electric circuit breakers - Google Patents

Abstract

486,050. Fluid - blast switches. GENERAL ELECTRIC CO., Ltd., and KEELEY, F. J. Feb. 2, 1937, No. 3068. [Class 38 (v)] In a circuit-breaker of the kind in which contact is made and broken between complementary contacts in an insulating fluid in a pot or chamber, circuit - interruption being effected at two or more series - connected breaks and the pressure produced by arcing at one break being used to quench the arc at the second break, the contacts of which separate prior to those of the first break, a single longitudinally-moving intermediate contact-member forms one contact of both breaks, the complementary contact of the first break comprises a rocking or pivoted contact disposed in the pot or chamber, and the complementary contact of the second break comprises a contact-rod adapted to extend into the pot or chamber, the second break being arranged to occur adjacent an aperture in the wall of the said pot or chamber. The Figure shows the closed position of an oil-immersed circuit-breaker having an insulating cylinder 5 provided with an aperture 10 and a horizontal shelf 11, above an aperture 13 in which a sleeve 16 is secured, the intermediate contact 17 being slidable in the sleeve to an extent limited by a head 18. A co-operating contact 19 is pivoted to a bracket 20 and linked at 21 to a collar 22 on an insulating tube 23, which is slidable in holes in the metal plate 4 and pot 5. This tube is normally biassed by spring 24 in a direction to separate contacts 18, 19, but the bias is overcome by a stronger spring 25 acting between the closed upper end of the tube and an insulating plunger 26 which is pressed upwards by the cross-bar 9. When the circuit is opened, the spring 25 raises the tube 23 and causes contacts 19, 18 to follow the contact-rod 15, until the head 18 engages the sleeve 16, whereupon 15 separates from 17 and draws an arc adjacent aperture 10. Before this arc can attain a great length, the plunger 26 is arrested by a shoulder 27 thereon engaging the tube 23, whereupon spring 24 forces the tube 23 downwards and separates 19 from 18. The arc thus produced sets up a pressure which drives oil downwards to put out the arc between the lower contacts.