GB630838A

GB630838A - Improvements in or relating to electric circuit interrupters having arc extinguishing means

Info

Publication number: GB630838A
Application number: GB34568/47A
Authority: GB
Original assignee: Westinghouse Electric International Co
Current assignee: Westinghouse Electric International Co
Priority date: 1947-01-04
Filing date: 1947-12-30
Publication date: 1949-10-21
Also published as: CH273218A; FR959368A; BE479338A; US2632075A

Abstract

630,838. Arc-rupturing in switches. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Dec. 30, 1947, No. 34568. Convention date, Jan. 4. [Class 38(v)] An air-break circuit-breaker has a magnetic blow-out structure wherein the cross-sectional area of the core 43 is less than that of one of the pole shoes 36 or 37, the ratio preferably being about 80 per cent, although it may be anywhere between 50 and 85 per cent. On opening, clockwise movement of contact carrier 8 about pivot 9 causes the contacts to separate in the following order : contacts 6, 15, 17, then secondary contacts 24, 26, and finally arcing contacts 25, 27. The loop effect caused by terminal' studs 3, 18, and carrier 8 helps to move the arc upwards into the interrupting chamber 2, this movement being aided by a blast of air through a pipe 23 and caused by the downward movement of a cylinder 20 relatively to a piston, not shown, on a rod 21. One part of the arc then roots on arcing horn 30, the arc being in position 32. The magnetic blow-out structure then forces the arc into a chute 39, the structure comprising two parallel-connected coils 34 in series with the arc, and wound on the core 43, the laminated pole shoes 36, 37, extending on either side of the arc chute and having depending sub-pole pieces 42. The portion 44 of the arc is moved to the left into a transfer interrupting stack 47, having an arcing horn 54, by means of of magnetic plates 59, 60. The plates 40 of chute 39 and 48 of stack 47 have tapered slots which are slightly staggered (Figs. 2, 4, not shown), so as to lengthen the arcs. The end plates 67 of the chute 39 are shortened so as to cause the arc gases to diverge, as at 69, thereby reducing the possibility of flashover. The magnetic flux is preferably made to lag the arc current by a small angle, e.g., 10 degrees. This may be done by (a) resistance-shunting coils 34, (b) eddy-current losses in the magnetic circuit, or (c) shading coils 71.