GB909508A - Electric circuit breaker - Google Patents

Abstract

909,508. Gas-blast switches. FEDERAL PACIFIC ELECTRIC CO. May 18, 1960 [June 24, 1959], No. 17603/60. Class 38 (5). In a circuit-breaker having an operating mechanism generally similar to that described in Specification 819,028, a spring- loaded piston opens the contacts when their operating mechanism is unlatched and produces a blast of compressed air to assist arc extinction, the piston and cylinder acting also as a shockabsorber towards the end of the opening operation. The common bar 28, which is pivotable about a shaft 32 to operate, through links 22, 26, the moving contact unit 18 of each phase, is coupled by a link 42 and a rod 54 to a piston 52 slidable in a cylinder 50 having a port 76 open to atmosphere and a port 86 which communicates with a space adjacent the breaker contacts through a conduit 88, a manifold 104 and three tubes 106. The piston 52 is biased by a spring 44 and carries a rod 92 on which slides a valve 96 co-operable with the port 86 and normally urged against a retainer ring 98 by a spring 94. A spring-controlled plunger 116 acts as a bumper for the bar 28 when it is rotated anti-clockwise to close the breaker, and also supplies an initial drive to the bar 28 when it rotates clockwise to open the breaker, a member 127 being engageable with a shock-absorber 129 to limit this clockwise movement. During its anti-clockwise rotation the bar 28 is coupled to a driving member 34, also pivoted at 32, through a latch 130 having an arm 132 carrying a roller 134 engageable with a face 138 on the member 34, rotation of the arm 132 about a pvot 142 normally being prevented by a rigid arm 136. To close the breaker a solenoid 40 is energized so that its operating head 38 engages a roller 36 to rotate members 28, 34, 130 and move the piston 52 to the position shown in Fig. 2, the bar 28 being held in this closed position, after the restoration of members 34, 38, by the engagement of the roller 134 with the face 145 of a spring-biased prop 143 pivoted at 144. To open the breaker a tripping mechanism (not shown) releases the arm 136 and hence the latch 130 to allow the spring 44 to rotate the bar 28 clockwise, movement of the piston 52 providing an air blast to the contacts until the valve 96 seals the port 86, after which the piston and cylinder cushion the final part of the opening stroke. The breaker may be fitted with a magnetic blow-out and an arc-chute.