GB714526A - Improvements relating to air-break circuit breakers - Google Patents

Abstract

714,526. Arc-rupturing in switches; switch contacts. SWITCHGEAR & COWANS, Ltd., and ROWLAND, F. G. Feb. 11, 1953 [Feb. 25, 1952], No. 4861/52. Class 38(5) An air-break switch has a deep arc chute 4 which completely envelops the fixed and moving contacts 5, 11, a hoop 19 of magnetic material around the chute above the level of the contacts, and separate fixed magnetic members 20 inside the chute and above the level of the hoop. When the arc 21 is drawn, it bows up into the space enclosed by the hoops and the flux set up by the arc links with the hoop 19. With light current arcs, Fig. 6, the flux inside the arc loops is strengthened to move the arc rapidly into contact with the magnetic members 20. The flux in linking with the hoop 19 and with the members 20 as the arc rises in the chute, brings the arc into close contact with a side of the chute, the ends of the chute and the members 20 to ensure maximum cooling and deionizing of the arc. Under high current arc conditions, the ends of.the hoop 19 saturate and some of the flux returns over the arc, Fig. 14, to prevent the arc rising too rapidly. The members 20 may be plates of magnetic material extending across the chute transversely to the arc. Alternatively the members 20 may be magnetic plates split longitudinally and provided with insulating centre portions or air gaps. In a modification, Fig. 16 (not shown), spaced plates of insulating material are provided and strips of magnetic material are inserted between them on both sides of the chute. The hoop 19 may be provided with an air gap at each end, and may be extended so as to link with a blow-out coil, Fig. 15 (not shown). Switch contacts: The moving contact assembly comprises pivoted arms 10 carrying a pivoted contact 11 which is biased by compression springs 13, 14. A stop 15 limits the movement of the contact 11 relative to the arms 10.