Patent GB-522514-A (GB)
Title: Improvements in and relating to electric switchgear
IPC: H01H33/00
Filed: 1938-09-12
Abstract: 522,514. Gas - blast switches; actuation of switches. AKT.-GES. BROWN, BOVERI, & CIE. Sept. 12, 1938, No. 26632. Convention date, Sept. 10, 1937. [Class 38 (v)] In a switching arrangement comprising an automatically-reclosing gas-blast circuit-breaker and a series-connected air-isolating switch interlocked therewith so as to open the circuitbreaker, and wherein the latter, on transient fault can be opened and closed at least once while the isolator remains closed, as in Specification 513,812, (Group XXXVII], the pressure in the quenching chamber of the breaker is maintained during such closure thereof, thus speeding up the switching operation and economizing gas-consumption. The isolating switch b and breaker a are mounted on a portable compressed air container c. The fixed breaker contact f<1>, has the movable hollow contact f<2>, carried by a piston f<4>, normally forced by a spring g against it. For normal operation, valve n is opened by hand or by closure of switch D to energize a solenoid r" controlling a valve q which admits compressed air from container c to depress the piston o carrying valves n against its spring. Air passes from the chamber e by way of a valve v, the space in slide valve st, and passage u<1> to the lower side of the piston f<4>. The contact f<2> is opened and air is led away until after quenching of the arc the piston f<4> opens a port u<3> by which air lifts a spring piston h' to raise a slide h and close the vents i. The pivoted or rockable isolating blade b is now opened either independently of, or in dependence on, operation of valve n, a mechanically - interconnected, electro - pneumatic drive being preferred for'the two switches. When valve n recloses, under the control of a damping device (not shown), it connects the chamber e to atmosphere by way of a vent in its stem, this vent being closed by a flap valve in the fully-open position of valve n. The contact f<2> closes and the slide h returns to normal. The circuit is remade at the isolating switch. On the occurrence of transient faults, the protective relay r operates a relay r<1> whereby a relay r<12> is energized in addition to r<11>. After the second opening of f<2> on fault, relay r<12> admits air through valve q<1> beneath the rod s of valve st, which is lifted to place the passages u<1>, u<2> in communication with the vent u<6> to atmosphere, whereby f<2>, h return to normal position. The return of h is ensured by the connection w which, when the slide st is up, places the passages u<4> above, the piston h in communication with the valve v. By suitable design of the relays, the reclosing may be repeated before the final opening of the circuit at the isolator. In Fig. 2 (not shown) a rotary valve replaces the slide valve st, whereas in Figs. 3, 4 (not shown) the actuating-pressure for f<2>, h is taken directly from container c, the movable contact in both cases being the lower one and forcibly returned to closed position by the gas-pressure. The Specification refers also to a pair of movable contacts formed as mirror images of one another and producing two breaks, the contacts and slides being simultaneously moved in opposite directions.