GB756592A - Pneumatically operated electric circuit breaker with closing valve cutoff switch - Google Patents

Abstract

756,592. Automatic circuit breakers; gas blast circuit breakers; switches partly electromagnetic. ALLIS-CHALMERS MANUFACTURING CO. March 1, 1954, No. 5976/54. Class 38(5) A controlling mechanism for a circuitbreaker 3 having contacts 4, 5 comprises a pneumatic motor 1 and a solenoidoperated gas inlet valve 90 the coil 94 of which is connected in series with a gas blast switch 97, a switch 96, and a power supply 95. When switch 96 is closed, coil 117 of an electromagnet 114 of switch 97, and coil 94 of valve 90 are energized, and valve 90 opens and admits gas to motor 1 forcing the piston and attached ram 18 upwards, the latter engaging roller 19 to raise a toggle 20, 23 which rotates lever 25 to cause engagement of contacts 4. 5 which are latched closed by a system 27, 31. In order to permit quick return of piston 15 to its original position by a spring 16, gas is admitted to switch 97 at a predetermined point in the closing stroke, which forces piston 100 up, thus separating contacts 98, 99 and thereby cutting off the supply to coil 94 and hence the gas supply to the motor. The piston 100 is attached to an armature 116 and electromagnet 114 locks unit 99, 100, 116 in the raised position which prevents re-closing of the circuitbreaker in case of latch failure. Gas in the motor 1 is dumped through a valve 58 as soon as latch means 31, 27 engage, On uncovering of 'orifice 66 by piston 15 during its upward stroke gas flowing through duct 67 depresses piston 60 which permits gas from the motor to enter through opening 62 which pushes piston 60 further down to uncover exhaust port 63. Valve 58 is maintained open, even if movement of piston 15 is reversed, by high pressure on piston 60. Tripping means for the circuit-breaker may be actuated either mechanically through a hand-lever 50 or a fault-responsive solenoid 49. It comprises a latch 45 which rotates in a clockwise direction on fault, and releases latch 42 and thus latch 34, a cam surface 37 of which (under influence of spring 6), releases roller 38 and allows pin 39 to slide in a groove 40 and lever 25 to move and contacts 4 and 5 to separate. A tail 33 on latch 34 releases the latch system 27, 31, a spring 55 then resetting the toggle ready for reclosure.