Patent GB-926948-A (GB)
Title: Multi-pole electric circuit breaker
IPC: H01H71/10
Filed: 1960-03-09
Abstract: 926,948. Electrically - tripped switches. FEDERAL PACIFIC ELECTRIC CO. March 9, 1960 [March 20, 1959], No. 8386/60. Class 38 (5). A circuit-breaker comprises three poles A, B, C, whose contacts are simultaneously opened and closed by movement of a handle 104 which operates two actuating mechanisms 66 situated in poles A and C, simultaneous tripping, due to a momentary or prolonged overload in one or more poles, being effected by a common tripbar 174 through a mechanism situated in the pole B. Each pole comprises two pairs of main contacts 20, 22 and a pair of arcing contacts 24, 26, the moving contacts 22, 26 being mounted on symmetrically-arranged blocks 30, 32 pivoted at 38 to a movable carrier 36, downwardly-biased by springs 52, 42 and limited in opening movement by the engagement of nuts 60, 50 with the spring cup 54 and the carrier 36. The block 32 has an arcing tip 34 extending into an arc-chute 28. The carriers 36 are pivoted at 64 in frames 62 and are rigidly interconnected by insulated bars 70, 72, each outer frame 62 forming part of the corresponding mechanism 66. Each mechanism 66 comprises a U-shaped member 80 pivoted at 82 in a frame 76 and connected by tension springs 100 (see Fig. 4) to a pin 84 on which pivot a pair of links 86 and a T-shaped member 88, the upper ends of the links 86 being pivoted to a releasable cradle 94 and the lower ends of the member 88 being pivoted at 92 to the carrier 36. The cradle 94 is pivoted at 98 to the frame 76 and its face 102 isnormally latched by a roller 236 so that anti-clockwise or clockwise rotation of the member 80 stiffens or breaks the toggle formed by members 86, 88 to close or open the breaker, each member 80 being secured to the bridge 106 of the operating handle 104. The roller 236 is carried by a frame 232 pivoted on a shaft 234 in the frame 76, the frame 232 being linked by a pin 226 to an insulating element 222 mounted on the end 224 of a shaft 194 and connected with a similar element by a part 216. The centre 216<SP>1</SP> of part 216 engages a part 212 (see Figs. 5 and 6) of a member 208 having arms 210 pivoted on the shaft 194 which is carried by the arms 196, 198 of a fixed bracket 154. The latter also has a pivot-pin 152 carrying a latch 150 biased towards the bracket stop 190 by one end 200 of a spring 192 mounted on the shaft 194, the spring portion 206 also biasing a portion 207 of the member 208 towards the stop 190. When the breaker is closed the latch 150 is biased clockwise to engage a part 172 of the trip-bar 174 by the engagement of a cam part 214 on one of the arms 210 with a roller 164 carried by the latch 150, this biasing force being derived from the cradle 94 and transmitted via the members 102, 236, 232, 226, 222, 216 and 208. The insulating trip-bar 174 is pivoted in arms 178 of the bracket 154 and is housed in an insulating casing 128 with bi-metallic strips 132 and electromagnetic trips associated with the poles A, B and C. In each pole the conductor 118<SP>1</SP> connecting the moving contacts to the terminal 14 is bent at a number of points to form a heater 134 for the strip 132, and a straight portion 138 which energizes a magnetic core 140 having an armature 142 biased therefrom by a spring 146 and connected to the trip bar 174. The latter may be operated, against the bias of a spring 180, by armature movement or by the engagement of the strip 132 with an adjusting screw 182, rotation of the bar 174 releasing the latch 150 and producing, through members 208, 216, 222 and 226, clockwise rotation of the frame 232 to release the cradle 94 and so trip the breaker. The roller 236 is biased by a spring 240 and moves in slots 238 to allow resetting of the cradle 94. The members 208 and 216 may be formed as an integral unit and a shunt 149 may be provided in each pole.