Improvements in and relating to electric circuit breakers having arc-extinguishing devices

摘要

575,855. Air-blast switches. BRITISH THOMSON-HOUSTON CO., Ltd. April 17, 1944, No. 7035. Convention date, April 17, 1943. [Class 38 (v)] An air-break circuit-breaker comprises a fixed contact structure 1 consisting of main contact 11, transfer contact 12, and arcing contact 13, all connected to stud 3, and a movable contact structure 2 consisting of main, transfer, and arcing contacts 8, 9, 10 respectively, connected through arms 20, pivoted at 4, to stud 5. When the rod 6 is moved downwards, the arms 20 to which it is pivoted at 7, are moved anti-clockwise. Contact 8 is fixed rigidly to arms 20, contact 9, which is urged in a clockwise direction and between the limits of stops 26, 27, by spring 23, is pivoted at 22 to arms 20. Contact 10 is insulatingly pivoted at 22, being fixed to arms 30 which, extending on either side of plates 20, are joined together by plate 31 which is connected to stud 5 by spring conductor 32. A spring eye bolt 34 fitted with lock-nuts 37, is pivoted at 7 and passes through insulating bearing 36 in plate 31, thereby biasing the contact 10 in a clockwise direction. When the breaker is opened, the arc formed at contacts 10, 13 is blown into the arc-chute 14 by blow-out coils 15-17, 15a-17a. To enable low-current arcs to be extinguished, a piston 40, operating in cylinder 41, is connected to a tubular piston rod which at its other end terminates in an expanding triangle-shaped nozzle 45. The rod is pivoted to contact 9 at 9a in such a way that the air-jet from the nozzle always blows across the arcing contacts. Specifications 537,311, 541,612, and 562,429, and U.S.A. Specification 2,280,616 are referred to.-