Patent GB-247972-A (GB)
Title: Improvements relating to electrical circuit breakers
IPC: H01H33/55
Filed: 1926-02-18
Abstract: 247,972. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Macneill, J. B.). Feb. 18, 1925, [Convention date]. Oil switches; automatic circuit-breakers.-Oilimmersed circuit-breakers are provided with a venting device for the tank which is arranged to be actuated by the operating mechanism of the circuit-breaker. As shown in Fig. 1, the venting device comprises a hollow plunger 58 in a housing 55 which is held in the position shown by a spring 57 while the circuit-breaker is closed, its movement being limited by a shoulder 61 at the upper end of the recessed peripheral portion 62 bearing on a fixed stop 59. In this position the tank communicates with the atmosphere through ports 66, 65 and also groove 62 and parts 63, the hollow interior 64 of the plunger parts 67, 68. During the opening of the circuit-breaker by rotation of the shaft 51 a cam 53 secured thereon engages an adjustable screw 69 projecting from the lower end of the plunger which is set so that while the arcs are being extinguished communication with the atmosphere is cut off and no oil can be ejected but at the end of the opening movement the communication is reestablished through parts 63, 65 the plunger interior 64, part 67, the peripheral recess 62 and part 68. The circuit-breaker is operated by longitudinal motion of a rod 17 attached to a crank 52 on the external portion of the shaft 51 on which is secured one arm of an adjustable toggle linkage attached to the operating linkage 46. The Specification as open to inspection under Sect. 91 (3) (a) also describes the operating mechanism which, as shown in Fig. 2 (Cancelled), consists of an operating lever 11 and an actuating lever 12 pivoted coaxially at 13, the lever 11 having an arm connected at 16 to the rod 17 and to a compression spring 14 and the actuating lever having an arm connected to a tension spring 15. A latch 18 is provided to connect the levers together, being pivoted to the actuating lever at 19 and having a lateral extension 21 bearing on a roller 22 carried by the lever 11. The latch 18 is operated by the armature 9 of a tripping electromagnet 8 through mechanism consisting of pivoted bell-cranks 24 and 27 and link 23 and 26 so arranged that the latch may remain in engagement during the collective movement of the levers 11 and 12 but may be disengaged at any point during this movement. The circuit-breaker is closed by the armature 7 of a closing electromagnet 6 attached to the lever 12, a roller 35 carried by a retaining detent 29 pivoted at 32 and provided with a centralizing spring 33 being moved aside by a lateral projection 34 of an extension of the lever 12. The roller 35 thus comes opposite the tapered recess between the end of the lever 11 and the portion 34 of lever 12 so that the levers are retained in position on de-energization of the electromagnet 6. The latch 18 is now tripped, the lever 11 is moved in a clockwise direction by the spring 14 and the weight of the parts to open the circuit-breaker and the lever 12 can now move aside the roller 35 so that the spring 15 can rotate the lever 12 until the latch 18 again connects the levers together in readiness for a subsequent reclosure. This subject-matter does not appear in the Specification as accepted.