Patent GB-480569-A (GB)
Title: Improvements in or relating to electric circuit breakers having arc extinguishing arrangements
IPC: H01H33/92
Filed: 1937-06-03
Abstract: 480,569. Liquid - blast switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO. June 3, 1937, No. 15413. Convention date, June 3, 1936. [Class 38 (v)] In a circuit-breaker having separable contacts for drawing an arc in an arc-chamber containing a dielectric liquid, pump means are provided for causing a flow of the liquid through the arc-chamber together with means for starting the operation of said pump means after the arc is extinguished to flush the arcchamber and for stopping the operation of the pump means after a predetermined period of time. The motor 95 is located on a housing 98 above the level of the liquid and drives a centrifugal pump 96 communicating by pipe 104 with openings in the metal collars 106 which support the bushing insulators 14. Liquid is thereby forced into the spaces 93 between the arc-shields 20 and the condenser-insulation 18 surrounding the lead-in conductors 16. Screwed to the base of each of the latter is a sealing plate 86 for the lower end of space 93, and a casting supporting a structure comprising a stack of five arc-quenching units 22. Each unit 22 contains a fixed contact 30 and a movable contact 32 arranged, when simultaneously separated, to provide five breaks in series, the contacts'32 being linked at 34 to an insulating operating rod 36 located centrally in the stack of units. A spring acts on the upper end of each rod 36 and the lower end of each carries a contact 38 co-operating with a movable bridge contact 40 on a lift-rod 42. When the latter is lowered, the springs retain contacts 38 in engagement with member 40, until the contacts 30, 32 are fully separated, whereupon separation of 38, 40 occurs. The arcs in the units 22 are quenched by means of a device in each unit comprising an arcuate slot 56 formed in a pile of alternating insulating plates 52, 54, such as fibre, plates 54 being formed with wider slots so as to produce liquidretaining pockets. Magnetic end-plates 46, 48 are separated from 52, 54 by fibre or other insulating plates 50, and have embedded in them coils 62, 64 for generating a radial magnetic field which drives the are along are-horns 58 arranged at the slot ends. Vents 65 for the arc-products are located along the arc-horns. A pair of pipes 73 formed by insulating tubes 74 extend the length of each unit, and adjacent pipes are interconnected by couplings 82, 76 the latter having radial passages connected by a cross-tube 78 branched at 80 to project into slot 56. The upper couplings 76 lead into a cross-tube 90 communicating with the space 93, through a passage in casting 86. The motor 95 is connected in circuit with a press-button switch which is closed when the breaker fully opens, and with a time-switch which cuts out the motor after a time-interval, the arrangement thus being such that flushing only takes place after the arcs are quenched. The latter action is assisted by a pair of checkvalves 92 in the ends of tubes 90, the valves having orifices 94 which admit pressure from the tubes 93 to the backs of the valves to hold them closed until the are-pressure subsides and to prevent liquid being forced back into the pump.