GB384819A - Improvements in electric switches with arc-extinction by selfgenerated vapour - Google Patents

Abstract

384,819. Arc-rupturing in hightension switches. RUPPEL, S., 8, Palmengartenstrasse, Frankfort - on - Main, Germany. Dec. 24, 1931, No. 35749. Convention date, Dec. 24, 1930. [Class 38 (v).] In a switch in which the arc is extinguished by the sudden expansion and condensation of vapour generated by the arc, the passage connecting the liquid chamber with a closed expansion chamber is substantially equal to the maximum cross section of the liquid chamber. In Fig. 1, a movable contact 1 extends through a piston 4 of insulating material which fits and slides in a liquid chamber 9. A gauge 10, from the bottom of which sludge may be tapped, connects the chamber 9 with an expansion chamber 6 and some .liquid is initially forced through it from the liquid chamber to the expansion chamber by the pressure, produced by the arc, which liquid assists the condensation in the chamber 6. After the switch has operated the liquid returns to the liquid chamber. An air-break switch 15, 17 is provided in series with the liquid switch. In Fig. 2, the movable contact 1 carries a piston 37 formed as a seal for the expansion chamber 6, the piston sliding in a guide tube 38, so that the volume of the expansion chamber increases as the switch opens. In Fig. 3 (not shown), a piston acts as a liquid chamber, and cooling ribs are provided for the expansion chamber. In another arrangement, two sets of contacts are provided in series, and springs are arranged to ensure correct operating sequence. In this case the contact rod may be entirely removed from the switch chamber since the hole through which it passes is covered by the piston in its raised position. In Fig. 5 (not shown), a concertina casing connects the expansion chamber with the contact rod, and assists a spring in ensuring correct switching sequence. The piston may be spring mounted on the switch rod so that the moment of expansion is influenced by the generated pressure, and a magnet energized by the switching current may be provided for accelerating the movement of the piston. The expansion chamber may be made of quartz or Jena glass. The liquid and expansion chambers may be resilient or may have plates covered with wire network adapted to fracture under excessive pressure.