GB452813A - Improvements in and relating to arc extinguishing means in electric circuit breakers - Google Patents

Abstract

452,813. Fluid - blast switches. SIEMENS SCHUCKERTWERKE AKT.-GES., Siemensstadt, Berlin. June 26, 1935, No. 18321. Convention date, Aug. 31, 1934. [Class 38 (v)] An arc-extinguishing device consists of a double nozzle which directs a current of compressed gas delivered at a central position between the nozzle openings in two directions axially towards the ends of the electrodes between which the arc is drawn. The gas is conveyed between walls of insulating material in which the double nozzle is formed and the distance apart of the nozzle openings is restricted to an extent such that the zone of low gas velocity located centrally between the openings is restricted to a minimum. The contacts are withdrawn in opposite directions along the axis a-a from a pair of nozzle openings 3, 4, which are coaxial with a-a and formed in the insulating walls 1, 2 of a channel by which the fluid is delivered, from all sides. A pair of ring-shaped members 10, 11 are inserted in the channel to restrict its cross-section in the neighbourhood of the nozzles, the resulting flow-lines being, as shown at 12, caused to penetrate as far as possible towards the axis a-a before being deflected at right angles, so restricting the cross-section of the arc at that point. In Fig. 4, the walls 14, 15 of the channel 13 are conically restricted, and the nozzle openings 16, 17 may be flared as shown in dotted lines. A contact 19 takes the arc when 18 moves out of engagement with the contact 20. The cross-section of the channel 13 is made equal to, or smaller than, the combined cross-sections of the nozzle openings. Arc resistant material such as steatite, carbon, slate, or tungstencopper alloy is used around the nozzle orifices in the restricted portion.