GB594979A - Improvements in and relating to electrical circuit breakers - Google Patents

Abstract

594,979. Automatic circuit-breakers. SOUTH WALES SWITCHGEAR, Ltd., and FARRER, S. March 2, 1945, No. 5252. [Class 38(v)] A circuit-breaker is closed by a mechanism wherein the energy of a resilient energy storing device is so transmitted through a rectilinearly moving member, a link and a shaft, that the torque required to reverse the shaft increases as the shaft rotates towards the position in which the switch is closed. Fig. 1 shows the mechanism in the open position of the circuit-breaker, which is actuated by rotation of the shaft 2. In this position springs 14 have been compressed by the counter-clockwise rotation of a manually - operated spindle 15 through links 16, 18, and a block 6 carrying tubes 11 on guides 12, a latch 19 engaging a pin 7 on the block 6. To close the circuitbreaker a spindle 21 is rotated manually or by remote control to cause a cam 22 to release the latch 19 from the pin 7. The block 6 is then forced upwards by the springs 14 and causes a link 5 pivoted at 7 to rotate a lever arm 3 secured to the shaft 2, which actuates the moving contacts through linkwork, part of which is shown in Fig. 3 at 25. Fig. 3 shows two sets of springs, one loaded and one unloaded, operating a common shaft 2, channels 9 guiding rollers 8 on the blocks 6. Buffer devices 23 stop the blocks 6 if the circuit-breaker closes easily, as on a small current. To prevent slow opening of the circuit-breaker by means of the spindle 15, a spring clutch, Fig. 6, comprising a spring 34 and a lever 33 may be fitted to an extension 2b of one end of the shaft 2. Recesses 31 in the lever 33 co-operate with projections 30 on the hub 3a of the adjacent arm 3, and the lever 33 trips the circuitbreaker through levers 36, 37 and an underset toggle mechanism. As an alternative to the construction shown in Fig. 6, the arm 3 may be loosely mounted on the shaft 2 and coupled to it through lost motion by a pin 40 and an abutment 39a on an arm 39, secured to the shaft 2, as shown in Fig. 7.