GB720331A - Improvements in or relating to electric circuit breaker employing high and low intensity gas blasts - Google Patents

Abstract

720,331. Gas-blast switches. ALLISCHALMERS MANUFACTURING CO. June 20, 1952, No. 15578/52. Class 38 (5) A gas-blast switch has an arc chute with two blast passages 15, 16 and a blast divider 19 extending from a point upstream of the switch contacts 7, 8 to direct a high intensity stream of gas into the passage 15 to interrupt relatively high currents and a lower intensity stream of gas into the passage 16 to interrupt relatively low currents. The blast divider 19 provides a pair of nozzles 22, 23 which diverge from the inlet end of the divider, the nozzle 22 being substantially coaxial with the supply conduit 13 and the passage 15 so that the major part of the blast flows through it. The nozzles 22, 23 are substantially closed by the moving contact blade 8 when in the position shown. The blast passages 15, 16 contain electrodes 25, 26, the electrode 25 being connected to the fixed contact 7 through a current-limiting resistor 27. When the contacts are opened, the initial movement of the contact 8 draws an arc and uncovers the nozzle 22, the blast through the nozzle 22 blowing the arc into the passage 15 where it comes into contact with the electrode 25. A portion of the arc is now shunted by the resistor 27 and extinguished. The portion of the arc in series with the resistor may be extended into the passage 16 as the contact separation increases and there extinguished by the lower intensity stream of gas which flows through the passage 16 when the contact 8 uncovers the nozzle 23.