GB647177A - Improvements in or relating to fluid-blast electric circuit breakers or switches - Google Patents

Abstract

647,177. Fluid-blast switches. LANGE. E. July 30, 1948, No. 20364. [Class 38(v)] On breaking a circuit, an arc formed in a chamber containing gaseous or liquid extinguishing medium or gas-producing solid, is short-circuited and thus extinguished after it has produced sufficient pressure in the chamber to form a stream of extinguishing medium for extinguishing a second arc formed in the interrupted circuit. A contact pin 3, Fig. 1, has an insulating tube 5 and a conducting point 13 which is connected to the pin 3 through resistance material 15. As the contact 3 moves up to break the circuit at a contact ring 2 on a metal block 6, an arc formed between the contacts 2, 3 is drawn into the chamber 1 whereby pressure moves the piston 7 to increase the chamber volume. When the tube 5 is above the contact 2 a second. resistance-limited, arc forms between the point 13 and contact 2 and shortcircuits and therefore extinguishes the first arc and is itself extinguished by quenching medium which streams from the chamber 1 through an outlet 4 which is now unobstructed by the tube 5. The ,outlet 4 is formed by a tapered insulating tube 14 which also prevents an arc striking between the point 13 and the block 6. In Fig. 2 the two arcs are formed in different parts of the chamber. A base-plate 43 forming on pole of the supply has two fixed contacts 22, 23 in a chamber 21 divided by an apertured partition 44, the other pole comprising a contact 42 connected through a rod 35 and a cable 37 to a contact pin 27 and the head 28 of a pin comprising an insulating tube 29 filled with resistance material 31 and having a conducting tip 30. The pins 27, 28 are pivoted to a lever 34 resting on stops 38 so that when the rod 35 lifts the lever 34 a pressure-producing arc formed between the contacts 22, 27 is short-circuited by engagement of the tip 30 with the contact 23 and the arc then formed between the contacts 23, 30 is extinguished by fluid exhausting through outlet 24. Stops 39 tilt the lever 34 so that the circuit is made by the pin 27. In Fig. 3, the contact 60 slides in fixed contacts 55, 65, 67 the supply being connected to contacts 55, 65. The contact 60 carries a conducting tube 64 insulated from it by insulation 71 so that on moving it down by the lever 59 an arc formed between the tube 64 and contact 55 is subsequently extinguished on engagement of the contacts 55, 60, the second arc between the contacts 55, 60 being limited by the resistance 70 and extinguished by the pressure produced by the first arc. This arrangement can be inverted for adaption to oil-blast, Fig. 4 (not shown). Fig. 5 shows a knife-blade switch 120 in series with the circuit-breaker, opening and closing after the breaker contacts 107, 128. On movement of the lever 106 on the shaft 110, the contact 107 moves down to break the circuit within the chamber 105 in the manner previously described, and a fork 115 pivoted at 113 eventually pushes an abutment 134 to rotate a shaft 118 whereby a link 124 opens the knife-blade 120. In this' position a spring-loaded pawl 116 engages a notch in a disc 117 to lock the shaft 118. On opposite movement of the lever 106, the contacts 107, 128 are closed whereupon a cam lobe 112 disengages the pawl 116 from the disc 117 and the shaft 118 is rotated by a tensioned spring 114 to rapidly close the blade 120.