GB971280A - Gas blast type electric circuit interrupters - Google Patents

Abstract

971,280. Gas-blast circuit-breakers; automatic circuit-breakers; pressure actuation of switches. WESTINGHOUSE ELECTRIC CORPORATION. Oct. 5, 1962 [Oct. 12, 1961], No. 37690/62. Headings H2B and H2K. A gas-blast circuit interrupter having separable contacts 5, 6 in a casing 3 filled with arcextinguishing gas, such as the interrupter of Specification 904,160, is provided with operating mechanism including a trip coil 47, a "closing" coil 37, a relay X for energizing the closing coil, and a switch 70 responsive to pressure in the casing and effective on low pressure to prevent the energizing of the relay X and the closing of the interrupter. The closing coil 37 may be the operating solenoid of the interrupter, but in the arrangement shown is the operating coil of a valve 34 controlling the admission of compressed air to an operating cylinder 31. Under normal conditions, the operation of a tripping switch CST causes the energization of the coil 47 to release a latch 46 so permitting the contacts 5, 6 to open under the bias of a spring 45. The interrupter is reclosed on the operation of a switch CSC which causes the energization of the relay X via contacts 101, LPC, 61 and 77, with the resulting energization of the coil 37, operation of the valve 34, and the closure of the interrupter contacts 5, 6. An " antipumping " relay Y is provided. Should the pressure in the casing 3 fall to a first predetermined value, a micro-switch unit 72 of the pressure-responsive switch 70 opens its contact 73, 77 to interrupt the circuit for the relay X to prevent a closing operation and closes contacts 73, 79 to complete an alarm circuit. In the event of a further fall in pressure, a second micro-switch unit 71 of the pressure-responsive switch 70 opens its contacts 73, 76 to interrupt the tripping circuit from the switch CST to prevent tripping. If, however, automatic tripping on loss of pressure is desired, a switch 98 is closed so that the trip coil 47 is energized when the unit 71 closes contacts 73, 78. Fig. 3 (not shown) illustrates a modified arrangement in which an alarm is given on the operation of the switch unit 72 and the switch unit 71 controls an additional relay which opens both tripping and closing circuits. In a further arrangement, Fig. 4 (not shown), the pressure-responsive switch has one micro-switch unit only. The pressure-responsive switch 70, Fig. 2, includes a diaphragm (not shown) which acts through a plunger 74 on a pivoted actuating plate 87 which is biased against the plunger by a spring 89, a spring adjustment 90 being provided.