GB388554A - Improvements in liquid brake electric switches - Google Patents

Abstract

388,554. High-tension switches sparking-preventing. RUPPEL, S., 8, Palmengartenstrasse, Frankfort - on - Main, Germany. Jan. 29, 1932, No. 2779. Convention date, Jan. 29, 1931. [Class 38 (v).] Sparking between switch contacts opened under a conducting liquid, is prevented by the provision, in parallel with the switch contacts, of a variable resistance which increases with the distance of separation of the contacts. In Fig. 1 the parallel resistance is formed by concentric electrodes 8, 9 immersed in the switch liquid, and connected with the switch contacts 1, 2. As the movable contact 1 is withdrawn, the liquid level in the parallel resistance gradually falls until the parallel resistance circuit is opened, when the main circuit is maintained between the contacts 1, 2 through the switch liquid, along a path restricted by a ribbed insulator 15. Thus when the liquid levels in the spaces between the electrodes 8, 9, and under a piston 6 attached to the contact 1, are the same, the final break is made between the contact 1 and the liquid, and any spark which then forms evaporates liquid which subsequently suddenly expands to extinguish the arc. The vapour pressure under the piston 6 is prevented from reacting on the liquid level between the electrodes 8, 9 by the piston 6 which covers ports 13 leading to the space between the electrodes. The electrode 9 carries an auxiliary contact 3 by which it is connected to the contact 1. The switch may have an additional visible separating point in air, and in switching on, the contacts 1, 2 may be connected without the interposition of liquid resistance. In a modification the parallel resistance is external to the switch, and the piston 6 connects one of the resistance electrodes to the contact 1. In a further modification this connection between a contact and an electrode is effected through the switch liquid. In Fig. 4, the contact 1 has a conical extension 42 acting as an electrode for the parallel resistance, the other electrode 39 of which is connected with the fixed contact 2.