GB756564A - Improvements relating to scavenging in high-voltage electric circuit-breakers - Google Patents

Abstract

756,564. Liquid-blast switches. REYROLLE & CO., Ltd. A. Sept. 1, 1954 [Sept. 2, 1953], No. 24307/53. Class 38(5) A circuit-breaker has a closed scavenging chamber 26 lying below or partly below the level 28 of arc extinguishing liquid in the circuitbreaker tank 21, the chamber having- a pressure-responsive inlet valve 29 exposed to the exhaust pressure in the circuit-breaker and a pressure responsive outlet valve 27 exposed to the pressure in the arcing region. When the circuit - breaker is opened, the pressure set up by the arcing between contacts 22, 23 closes the outlet valve 27 and the pocket of gas 30 in the upper end of the chamber 26 is compressed by the exhaust pressure. As the discharge of arcing products proceeds, the pressure in the region of the contacts drops, the inlet valve 29 closes and the pocket of gas 30 is left at a higher pressure than the liquid outside the valve 27, so that the valve 27 opens and liquid is driven out of the chamber 26 by the expanding gas bubble 30 into the arcing zone to scavenge the arcing products from the contacts. When the pressure inside the chamber 26 equals that outside, the inlet valve 29 falls open or leaks, enabling liquid to flow back into the chamber 26 through the outlet valve until equilibrium conditions are established. In the Figure shown the circuit-breaker is of the small-oilvolume type and has the chamber 30 above an arc control device 20 but in Fig. 3 (not shown), a similar type of circuit breaker has the scavenging chamber mounted at the side of the are control device and wholly immersed. In Fig. 1 (not shown), the circuit-breaker is of the bulkoil dead-tank type.