GB762988A - Improvements in electric circuit breakers of the air- or gas-blast type - Google Patents

Abstract

762,988. Gas-blast switches. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 25, 1955 [March 2, 1954], No. 6119/54. Class 38(5) In an air or gas-blast circuit interrupter, a resistor 28 is connected in parallel with the contacts 11, 14, by means of electrodes 31, 32 arranged in a closed pressure-retaining chamber 34 and which provide a gap in series with the resistor, which gap will break down when contacts 11, 14 are opened, and means are provided for the application of air or gas pressure to the gap to quench the spark thus formed and terminate the flow of current through the resistor. The interrupter is operated by opening control valve 37 to apply pressure from pipe 40 to the contact chamber 1, urging contact 11 away from contact 14. Air flows through contact 11 and ports 11a into casing 6. The pressure moves piston 23 downwardly against spring 24, opening ports 22 to the atmosphere. The flow of air extinguishes the arc drawn between the contacts and withdraws air through pipe 35 from chamber 34, facilitating the breakdown of the gap between the electrodes 31, 32. On further movement of contact 11, piston 13 exposes port 27 so that pressure is applied to the underside of piston 23, causing it to rise and close ports 22. The pressure in the casing 6 then builds up to that in chamber 1, and is finally applied through pipe 35 to chamber 34 to interrupt the spark therein. The contacts 11, 14 are closed by closing valve 37 and opening exhaust valve 37a. The interrupter may include a series isolator (Fig. 2, not shown), the opening of which may cause the opening of valve 37a and thus the closing of contacts 11, 14. Two contact units may be mounted back-to-back to extend in opposite directions from assembly 2, each unit having a resistor and series gap in parallel with its contacts (Fig. 3, not shown).