Patent GB-797412-A (GB)
Title: High voltage magnetic arc extinguishing means for electric circuit breakers
Inventor: WOOD JOSEPH D
IPC: H01H9/34
Filed: 1955-01-10
Abstract: 797,412. Arc-rupturing in switches; automatic circuit-breakers; switch gear structures. I.T.E. CIRCUIT BREAKER CO. Jan. 10, 1955, No. 722/55. Class 38 (5). The arc-quenching structure of a circuitbreaker comprises insulating side walls 257, and a series of arc extinguishing plates 260, preferably of glass-bonded mica, each provided with a slot 303 having three distinct sections; the first having an opening 304 central of the plate, the second defined by edges 310, 309 and the third by parallel edges 308, 312. The plates have integral flanges 261 and are arranged alternately so that the last two sections of the slot in alternate plates are on opposite sides of the vertical centre line of the stack and thus provide a sinuous path for the arc. In a modification (Fig. 9A) each plate is T-shaped. The arcquenching structure is incorporated in a circuitbreaker mounted on a trolley having three wheels, and further wheels co-operate with tracks in a compartment to guide the breaker. The operating mechanism 46 is supported on a cross-bar 74, and utilizes the principle of a lever operated switch with enough addition to provide automatic overload tripping and to provide solenoid closing means. Trip unit 48 is stated to be standard. The movable contact assembly 50 is supported on the front end 152 of a copper bar 150 of the lower terminal assembly 31, said bar being insulated by a phenolic tube 151 with a conductive inner lining. The upper terminal assembly 30 comprises a copper bar 160, similarly insulated, and carries the main disconnect contacts 38, and stationary main and arcing contacts 167, 166 with which co-operate movable contacts 185, 206 carried by movable contact arms 80, 204, respectively. Arm 80, comprising two bars 180, 181, pivots on a pin 200 connected between bars 180, 181 and carrying link 51 connected to contact operating arm 52, a pin 187 being received in openings in bars 180, 181 and in a slotted opening 188 in the lower terminal 31. Compression springs 193 retained between flanges 157 on terminal 31 and lugs 190 on the pin 187 bias the contact arm 80 to contact-open position. When the arm reaches the contact-closed position the movable contact 185 bears against contact 167 and as link 51 forces pin 200 and arm 80 into closed position spring 193 yields and pin 187 moves in slot 188, thus permitting a wiping action between the contacts. Contact between arms 181, 180 and terminal 31 is made by insert contacts 202 in the terminal and by the lower ends of the arms 181, 180. The arcing contact arm 204 carrying contact 206 and arcing horn 207 is pivoted on a pin 205 between arms 180, 181, a floating pin 210 connecting the lower end of arm 204 to a link 211 which bears against a milled surface 212 of a pin 213, and tension-spring 215 rotating link 211 clockwise and collapsing toggle 211-210-204 and biasing arcing contact 206 to contact closed position, an adjustable screw 220 bearing against 204 determining the position of collapse of the toggle. It is stated that the making and breaking of contact at the arcing contacts is ensured before and after the making and breaking of the main contacts by the position of pivot 205 above the centre of arm 204 and that a blow-on action of the arcing contacts occurs. An insulating shield 230 protects terminal 31 against arcing damage. A blow-out assembly 53 comprises a coil 54 wound on an iron core 240 to which are secured iron legs 55, one end of the coil being connected to terminal bar 168 and the other to contact bar 171. Specification 791,613 and U.S.A. Specification 2,029,028 are referred to.