GB379804A - Improvements in or relating to electric power switches - Google Patents

Abstract

379,804. High-tension switches. SIEMENS-SCHUCKERTWERKE AKT.-GES., Siemensstadt, Berlin. July 2, 1931, No. 19155. Convention date, July 3, 1930. [Class 38 (v).] In a switch of the "expansion" type, in order to ensure that adequate vapour pressure is developed by the arc so that when the pressure is relieved the vapour expansion will be sufficient to ensure de-ionization of the arc path between the contacts 21, 22 immersed in water or oil, the cover 14 of the pressure chamber 10 is held down by springs 17, 18 and when raised opens up a large peripheral passage for the expansion. In addition, the cover has a depending flange portion 19 so that when it has been raised slightly the flange passes beyond the inner edge of the container thereby exposing an additional area of the cover to the pressure developed in the container and ensuring that the cover does not return until the pressure has decreased substantially. In an alternative construction, the pressure chamber is yieldingly mounted on a base within an exhaust chamber containing liquid and communicating with the pressure chamber. When the necessary pressure is developed, the chamber is lifted to allow the expansion to take place. As shown in Fig. 3, the expansion chamber (containing liquid and immersed in liquid) is made up of an insulating cylinder surrounding the fixed contact fixed to the base and carrying, fixed to its upper end, an insulating ring 43. Above the ring 43 a nest of rings 49 is arranged with orifices to admit the pluglike contact and with spacing rings 44 between. The whole structure is held together by spring bolts between upper and lower endplates 50, 41. In the case of rupture of heavy currents an adequate pressure is developed at the lower end of the chamber by a short arc and the lower ring 49, together with all above it, is lifted against the action of the springs 59, 60. This leaves two passages above and below the lowest spacing rings 44 for the expansion and provides for the additional pressure surface to prevent premature return of the rings to the normal position. With less heavy currents, a longer arc is necessary to develop the pressure which is no longer confined to the lower part of the chamber and is effective to separate the upper rings and thereby provide additional spaces for the expansion.