GB392051A - Improvements in or relating to liquid electric power switches and the like - Google Patents

Abstract

392,051. High-tension switches. SIEMENS-SCHUCKERTWERKE AKT.- GES., Siemensstadt, Berlin. Sept. 19, 1932, No. 26036. Convention date, Nov. 28, 1931. [Class 38 (v).] The movable pin contact of a switch of the "expansion" type is withdrawn from the fixed contact at a speed in excess of three metres per second whereby a maximum vapour pressure, ready for the expansion effect, is produced with a minimum of arc energy and re-establishment of the arc is avoided by the rapidly-produced gap so that the circuit may be interrupted at the zero of the cycle during the first half wave. The rapid movement is produced by a powerful spring 20 which has a flexible connection 31 with the sector 30 pivoted at 29 and carrying a crank 23. The sector is held in the position shown with the spring stressed by a catch and the sector is so shaped that as it rotates the mechanical advantage of the spring in producing the rotation is reduced. The crank is pivoted to the middle of a link 21, one end of which is pivoted to a block mounted on the switch pin 14 and constrained to move between the rails 18. The pin engages the fixed contact 13 in the switching chamber and is surrounded by spring-pressed rings which conserve the vapour pressure developed until it is adequate to extinguish the arc by sudden expansion. In the position shown, the linkage system is near its dead-centre position so that the spring has a double mechanical advantage (that due to the shaped sector and that due to the position of the linkage) in effecting initial movement of the switching pin. Thereafter, the speed of the pin is rapidly increased and at an intermediate position the free end of the link 21 engages jaws 34 by which it is momentarily retained while the crank stll further raises the pin and, the free end escaping, drives the pin into the neighbourhood of the second dead-centre position.