GB537180A - Improvements relating to closing mechanism for an electric circuit breaker - Google Patents

Abstract

537,180. Automatic circuit-breakers; actuation of switches. BRITISH THOMSONHOUSTON CO. Ltd., and HUNTER, M. C. I. Dec. 11, 1939, No. 31952. [Class 38 (v)] A circuit-breaker closing mechanism of the type in which operation is effected by release of energy stored in a spring, employs flywheel means which absorbs part of the initial spring-energy and gives it up again when the breaker-parts are beginning to slow up due, for example, to shortcircuit forces. The flywheel means comprises a pair of co-axial flywheels one behind the other, pivoted on stub axles 5 and interconnected by a crankpin 4 which is coupled through a lever 7 to a lever 8 pivoted at 9. Lever 8 is linked at 10 to a cross head 11 between which and a fixed abutment 14 the spring 13 is compressed. The crosshead also carries a cylinder 15, the bottom closure 17 of which supports a loaded damping spring 18 bearing on a plunger 19 on which abuts the plunger 2 connected to the contacts (not shown) through trippable mechanism. To stress the spring 13a, a motor, Fig. 2 (not shown), is driven, or handle 28 continuously oscillates a lever 24 whereby a pawl 25 thereon engages ratchet teeth 20 on the front fly-wheel 3a to rotate it progressively clockwise from the position shown to a position where the pin 4 is just past the lower dead-centre whereat the parts are held by a releasable roller 22 engaging a notch 21 in the rear flywheel. At this point, indicated by a switch 36 operated by roller 22, the ratchet teeth come to an end and the roller 22 can be operated to release the stored energy either by a push rod 37 or by a solenoid 38. A retaining pawl 31 engages the teeth 20 to prevent backward rotation of the flywheels by spring 13 during the charging operation, when the crosshead 11 is being lowered. When tripped to close, the crosshead rises and pushes up the rod 2 and when the breaker is tripped, and with the spring 13 charged, the rod 2 falls under gravity assisted if desired, by a light spring, to reset the automatic trip mechanism. In a modification suitable for a smaller breaker, Figs. 3, 4 (not shown), the closing spring is arranged to lower the rod 2 to close the contacts. the rod 2 being raised again by a light spring and having a modified form of connection with the crosshead.