GB735934A - Improvements in or relating to electric switches incorporating means for dousing with extinguishing fluid, arcs arising on separation of the switch contacts - Google Patents

Abstract

735,934. Fluid-blast switches. CALOREMAG ELEKTRIZITATS-AKT.-GES. March 17, 1952 [March 15, 1951; March 17, 1951; April 2, 1951; April 2, 1951; June 18, 1951; Aug. 4, 1951], No. 6897/52. Class 38 (5). In an oil or gas-blast switch, the arc struck between the hollow movable contact 1 and fixed contact 2 is extinguished by fluid driven from within a movable pumping piston 5 through a nozzle 6 into an arcing chamber 9 and thence via vents 8 into an outer chamber 10 at considerably lower pressure, the vents 8 being of such size that the minimum fluid-pressure within the chamber 9 is adequate for arc-extinction whilst the wall 3 of the chamber 9 can resist the maximum pressure. In the closed position the piston rests on contact 2 and is, in opening, picked up by a ring 12 on the contact 1 engaging a shoulder 13 on the piston, this engagement slowing - the movement of the contact to give arc-extinction at a short gap. In closing, the contact 1 may move independently of the piston, but preferably the two are locked at 25, the lock being released by a ramp 30 in the closed position. With high internal opening pressures, a ring 14 is forced upwards against springs 17, valves 28 allowing filling of the piston during closing. A spring-buffered piston ring 21 enables high pressure to be built up in the chamber 9. Alternatively, elastic gas containers or solids may be provided to absorb these pressures. The above may be adapted for a back-to-back arrangement of two series breaks with an additional mechanical blast applied between, so as to issue from, the two fixed contacts (Fig. 2, not shown), or applied to the spaces within the pistons 5 (Fig. 3, not shown). As a modification of the last-named arrangement, the pressure in the chamber 9 may act on one face of a differential piston, the opposite face of which communicates with the interior of the pumping piston to give an added blast (Figs. 6, 7, not shown). In Fig. 8, the movable contact is made of differing overall diameters, whereby the aperture 83 is filled by the thick part 82 in the extinguishing position shown and remains so until the switch is almost fully open, whereas in closing, when the aperture is freed and similarly an aperture 86 in the piston is cleared by the part 12 of the movable contact, fluid can enter the piston. In all forms, the tubular contact 1 is vented at 23 to the space 10.