Patent GB-350529-A (GB)
Title: Improvements in electrical switches or circuit breakers
IPC: H01H33/92
Filed: 1930-03-10
Abstract: 350,529. Oil-break switches ; switch gear structures. WHITEHEAD, G. E. and WHITEHEAD'S ELECTRICAL INVENTIONS, Ltd., 102, St. Mary Street, Cardiff. March 10, 1930, No. 7750. [Class 38 (v).] Heavy current oil circuit-breakers h a v e co-operating contacts within a tubular arcquenching chamber located in the main oil tank, so as to provide a free oil channel open at both ends to the main oil tank, means being provided to cause the oil at break to flow under pressure through the channel and around the contacts. In the construction shown in Fig. 1, the tubular movable contacts are carried on a spider 6 capable of up - and - down movement on the guide-rods 7 fixed within the oil tank (which has an insulated lining 9), while the fixed contacts 3, which are covered with insulation 5 except on the ends, are carried by a fixed crosshead 4. Above the spider 6 two crossheads 13, 14 are arranged to slide together on the guide-rods under the control of the springs 19. They are permanently spaced apart by insulating tubes 18 which surround both contacts and constitute arcing chambers. When (on operation of the rod 11 and the links 17<1> connected with the crosshead 14) the switch is moved to the open position shown, the downward movement of the piston-like crosshead 14 (which at a certain stage is effected positively by the cross-pin 22) produces an upward stream of oil through the comparatively restricted space in the sparking chamber. In order to provide for isolation, the fixed contacts may be furnished with sockets, so that, by withdrawing the switch as a whole, it may be isolated from the plugs 21. Automatic circuit-breakers.-In the form shown in Figs. 2 and 3 as a three-phase oil circuit-breaker with two breaks in series per phase and with isolating arrangements, six fixed renewable contacts 1 are arranged concentrically and are engaged by six similarly-arranged movable contacts 2 with an interposed ball 60 as described in Specification 337,056, [Class 38 (v), Electric switches &c.]. Each pair of movable contacts is mounted, by means of an integral cross member, on the arms of a three-armed spider 6 actuated by the rod 11. The single movable crosshead 14 carries the tubular arcing chambers 18. The actuating member 11 is automatically coupled to the screw-threaded operating rod 34 by the catch 40 and the switch may be brought to the closed position, through bevel and other gearing, by rotating the handwheel 37. It is tripped (on overload &c.) when the trigger 51 is raised, whereby the lever 47 is released and under the action of the spring 50 gives the arm 44 of the catch 40 a hammer release blow. As before, in descending, the crosshead 14 forces oil through the arcing chambers and over the contacts. For isolating purposes, the " fixed " contacts at their upper ends may be secured to an additional crosshead 4, Fig. 2, sliding on the rods 7 so that, by coupling this crosshead to the rod 34 by means of the hand-actuated latch 57, the "fixed" contacts can be lowered for isolating purposes by actuating the hand-wheel 37. Provision may be made for bus-bar selection by means of three additional fixed contacts (all of the nine contacts being concentric) and rotating the movable contact structure through 40 to select the alternative bus-bar. More breaks per phase in series may be provided for by means of a further crosshead below those described. The contacts may be of the form described in Specification 347,606.