GB575854A - Improvements in air-blast electric circuit breakers - Google Patents

Abstract

575,854. Air-break switches. GORDON, H. H. (Allmanna Svenska Elektriska Aktiebolaget). April 17, 1944, No. 7034. [Class 38 (v)] The arc-extinguishing chamber of a transverse air blast circuit breaker is divided into two parts 10, 11 by an insulating wall 5, made, for example, of polymerized derivatives of acrylic acid, or resins of aniline, to which are fixed insulated auxiliary electrodes 16, 21. Main electrodes 14, 19 are connected to contacts 12, 17 respectively and are electrically joined at the ends to the electrodes 16, 21 by webs 15, 20. The lower edge 22 of the insulating wall 5 has a notch 23 to hold the arc at the middle thereof. In operation, the arc drawn out between contacts 12, 17 is blown upwards by the air blast from pipe 9. The footpoints of the arc run up electrodes 14 and the arc is pressed against edge 22 and contacts tungsten tips of electrodes 16, 21, whereby the arc burns round the edge 22 from electrodes 16 to 21 and is extinguished by the air-blast. The main and auxiliary electrodes may alternatively be connected through a resistance which, inserted in the arc circuit, limits the current through it. An arrangement suitable for higher voltages uses a plurality of insulating walls, Fig. 3 (not shown). In Fig. 4, the auxiliary electrodes 16, 21 are connected through a resistance 38 which is thereby in parallel with the arc. The resistance of the arc increases due to the blast pressure and the current rapidly becomes too small to maintain the arc which is therefore extinguished. Instead of the main and auxiliary electrodes being connected, two extra walls 41, 42, are inserted to extinguish the remaining arcs. Fig. 5 shows an arrangement wherein two extra walls 45, 52 with auxiliary electrodes 46, 49 are fitted. Connections are made between electrodes 14 and 46, etc., as shown, electrodes 16, 21 being connected by resistance 38. Arcs form round the tips 50, 51, 22 of the walls.