Patent GB-544092-A (GB)
Title: Improvements in automatically reclosing circuit breaker systems
IPC: H01H75/04
Filed: 1941-05-09
Abstract: 544,092. Protective cut-out arrangements ; liquid-blast switches. BRITISH THOMSONHOUSTON CO., Ltd. May 9, 1941, No. 6017. Convention date, May 11, 1940. [Class 38 (v)] An automatic reclosing circuit-breaker has a liquid-pressure actuated contact 20 carrying an insulating piston 21 which is raised by the pressure (which also forces an arc-quenching blast through the bore 23) set up by a plunger 14 under spring-action 16 when released on overload. The contact is opened against spring- action 30 and latched by a ratchet 31 and pawl 32 which is electrically released at 34 to allow spring 30 to reclose the breaker. If the breaker reopens, as in the case of a persisting phasefault to earth, the breakers in the other phases are automatically opened. The plunger-rod 15 carries a rack 39 meshing with a pinion 42 on a sleeve 50 yoked to a ring gear 45 forming part of a sun-and-planet gearing of which the sun wheel 47 drives a shaft 52 rotatable in sleeve 50. A stop 53 normally retains shaft 52 by engaging a pivoted arm 55, 57 which is moved to the release position by spring 56 and restored by a cam 54 and arm 60. The retaining magnet for the arm 55, 57 comprises a core 58 with a holding winding 62 and flux-shifting trip coil 63 both energized from a D.C. source 64, 65. Coil 63 is in series with reversely-connected, normallysaturated, current-transformer secondaries 66 so as to provide a tripping current on overload in the line. The rack 39 carries a control panel 40 on which are contacts 70 ... 73 co-operating with a series of brushes 74 ... 80. When one of the breakers is tripped the plunger 14 and-panel 40 move from position A to position B. Soon after leaving A, contact 72 bridges brushes 77, 78 to energize a motor 41 which drives through worm gearing 44 and rods 48 the planet wheels 46, but without effect until the stop 53 has .made a complete rotation and engaged the reset latch arm 55. At this point, position B, contact 70 bridges brushes 74, 75 and energizes the coil 34 to allow the breaker to reclose. The motor then, provided the breaker stays closed, restores panel 40 and plunger 14 to position A and restresses spring 16. If, however, the fault persists and magnet 59 again releases stop 53, the rotation of the motor 41 is again rendered ineffective and panel 40 and plunger 14 move from position B to position C,.thus re-opening the breaker. Soon after leaving position B, contact 73 engages brushes 79, 80 energizing a relay 85, 86, or 87, which opens at contacts 82, 83, or 84 the circuit of all the holding coils 62, so that the remaining breakers open. Since the coils 62 are not energized, stops 53 are inoperative at position B and accordingly their panels 40 move direct to position. C. The contacts 73 energize the remainder of relays 85 ... 87, thereby closing contacts 91 ... 93 to energize a time-relay 90 which closes contacts 94 to re-energize coils 62, arrest shaft 52, and render the motors 41 inoperative to restore the panels' and plungers to position A. During this movement the contact 70 would cause the breaker to be tripped to close again and accordingly a special construction of contact 74 is provided to prevent this, Fig. 3 (not shown). In position A, contact 71 bridges brushes 75, 76 whereby the breakers can be reclosed manually at 81.