Patent GB-368969-A (GB)
Title: Improvements in and relating to electric switch operating mechanism
IPC: H01H3/30
Filed: 1931-02-28
Abstract: 368,969. Automatic circuit-breakers. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.- (Assignees of Clarke, P. C. ; 200, White Horse Pike, West Collingswood, New Jersey, U.S.A.) Feb. 28, 1931, No. 6324. Convention date, Feb. 28, 1930. [Class 38 (v).] Electric-motor actuation centrifugal actuation. -The movable contacts 3 are lifted into the closed position by a straight-line moving rod 6 acting on member 1 through links and levers having fixed pivots at 9, 14, 17, 22. During closure, a powerful opening-spring 25 is first stressed by means of a motor 23 actuating through a centrifugal device 26 a centrallypivoted lever 27 which is linked to the common pivot of a toggle 29, 29<1> which is in turn connected to a lever 31. The link 29<1> is pivoted at 55 to a lever 30 having a fixed pivot 30<1> and to a link 53 normally held by a trippable toggle 46, 46<1> which can be broken by means of a tripping armature 50 knocking aside a latch 48. Thus the toggle 29, 29<1> is moved to the overset position, where its common pivot abuts a stop 31<1>, and rotates the lever 31 about its pivot 32 and moves the member 36 downwards away from the end 37 of the rod 6, so stressing the spring 25. The motor 23 is then stopped and the motor 24 started, the latter acting through similar toggles to move the rod 6 downwards until members 36, 37 again engage, thereby closing the breaker. The toggle 46, 46<1> can be tripped at any stage of the closing movement to provide a free-handle feature, but to avoid the impact of spring 25 on the rod 6, a shockabsorbing coupler can be interposed between them, Fig. 4. The latter comprises a piston 63 apertured at 64, the rod 62 of which is connected at 67 to the crank 31 and apertured to receive the stem 66 of a valve 65 adapted to close the aperture 64. The piston 63, in closing the switch, moves freely down the cylinder 60, which is secured to the rod 6, the fluid in the cylinder raising the valve 65 to allow this, and the stem 66 engages at the end of its travel with a stop 68 to keep the valve lifted and enable the cylinder to follow the piston. If, however, owing to the free-release operating, the spring 25<1> rises, after a short time the stem leaves the stop 68, so allowing the valve to drop and close the apertures 64. The piston and cylinder then move together to raise the rod 6 and open the switch. In a modified form, Figs. 6-9 (not shown), a single motor is adapted to perform the operations of spring-stressing and circuitclosing, the motor making two similar but independent movements over the same path. In the first movement the motor is coupled to the end of lever 27 to stress the spring, but is prevented by a catch arrangement from engaging the second lever to close the switch until the second movement. The link 53 is dispensed with and the toggle levers 29<1>, 40<1> are both pivoted to the lever 46<1>. In Fig. 10, a motor-driven cam 101 on a shaft 100 first rotates a lever 103 clockwise about its pivot 103<1> to stress the spring 105, the lever 104 remaining stationary. After half a revolution the cam 102 rotates the lever 104 countrclockwise, thereby lowering the stressed spring 105 bodily and lowering the rod 6 to close the switch. During this movement the pivot 104<1> remains held by the tripping lever 106, but may be released at any time by the trip-coil 108 to open the switch.