GB1104228A - Improvements in or relating to electric circuit breakers - Google Patents

Abstract

1,104,228. Liquid break switches. J. L. GRATZMULLER. 20 Jan., 1966 [21 Jan. 1965; 5 Jan., 1966], No. 2685/66. Heading H1N. In a circuit-breaker the arc is quenched in a chamber 2 containing an insulating fluid which. is kept in its liquid state at normal ambient temperature by pressurization. The fluid may be liquefied SF 6 ; SeF 6 ; C 3 F 8 ; CF 3 SF 5 or one of the perhalogenated hydrocarbons known under the Trade Mark " Freon." In a first embodiment (Fig. 1, not shown), the sealed chamber (2) is mounted upon an oil-filled insulator column (4) through which passes an insulating rod 18, connecting the moving contact (6) with an hydraulic actuator (16), and an insulating tube (24) connecting the interior of chamber (2) to a lower chamber (26) of an accumulator (28); the upper chamber (32) of the accumulator, above a free piston (30), is filled with compressed nitrogen gas serving to absorb fluctuations in pressure in the liquid due to changing temperature. An escape valve (38) permits air to be bled from the system. In a modification (Fig. 2, not shown), the interior of column (4) also is filled with the insulating fluid and is in direct communication with chamber (2). The escape valve is replaced by a return connection (44) to the accumulator (28<SP>1</SP>). In a further modification (Fig. 4) both the tubes 24, 44 are within the column 4. Non-return valves 46, 50 are located in these tubes permitting only one way circulation of the liquid between chamber 2 and the accumulator. Such circulation is caused by the fluctuations in pressure caused by changing temperature and may be enhanced by a pump 64. A filter 60 may be included to remove impurities from the circulating liquid. In a further modification (Fig. 9, not shown), the separate accumulator is replaced by an additional chamber (108), above chamber (2) which contains the compressed nitrogen. The accumulator (Fig. 8, not shown), or chamber (108) may be fitted with a sight glass (98) for observing the level of the insulating liquid. Means are also described for filling the circuitbreaker with the insulating liquid either by distillation (Figs. 5, 6, not shown), or directly (Fig. 7, not shown).