Patent GB-599229-A (GB)
Title: Improvements in or relating to fluid-blast electric circuit interrupters
IPC: H01H33/70
Filed: 1945-10-17
Abstract: 599,229. Fluid-break switches. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Oct. 17, 1945, No. 27228. Convention date, Oct. 17 1944. [Class 38(v)] In a fluid-blast circuit - interrupter, the diameter or narrow dimension of the exhaust orifice is made substantially equal to the product of the fluid velocity and half the natural frequency of the circuit, so that the contaminated fluid is replaced with pure fluid in a time less than the natural frequency. The theory underlying the invention is set out in detail in the Specification with the aid of curves, Figs. 32-39 (not shown). In a form having two breaks in series, Fig. 5, oil or water under pressure is forced into the arc-extinguishing structures 10 to separate contacts 12 from orifice contacts 11 against spring pressure. Fig. 8 shows an embodiment wherein an operating lever (not shown) moves a piston rod 49 downwardly, thereby producing a blast of liquid through a passage 56 in a cylinder 69 and across the contacts 59, 60, the latter being opened by a linkage 34 connected to the operating mechanism. Triangular baffles 76 are arranged to dissipate the momentum of the jets of liquid through the orifices, the liquid then passing into a chamber 31 surrounding the cylinder 44. The movable contact 60 is slidable in an end plate 70 of the cylinder 69, but in a modification, Fig. 9 (not shown), the contact is mounted on a flanged member which slides on a ring screwed onto the lower end of the cylinder 69. In Fig. 13, the contact. has slots 101 filled with oxidised or enamelled sheet metal, thereby causing the arc to be driven magnetically inwards to the orifice 103. In Fig. 21, the movable contact 105, in its closed position, bridges two pairs of co-operating spring-pressed contacts 108 which, when the contact 105 is withdrawn, move laterally inwards to form orifices 103 between them. In Fig. 23, the movable contact 88 has a cam 89 which, on opening of the contact, engages two spring - pressed rollers 90 on bell - crank levers 85, thereby causing gate-members 84 to slide inwards to form an orifice 58. The members 84 each comprise two plates 94, 95, separated to form an inlet passage between them. In a modification, Fig. 26, the plates 94, 95 have conducting tips 96 connected respectively to the contacts 92, 88, so that when the latter is withdrawn, an arc 91 drawn between the tips 96 is blown towards the orifice 58. In Fig. 27a, an air blast is injected through a pipe 126 and is exhausted through an orifice 124 and a passage 125 in the movable contact 116. In a modification, Fig. 27 (not shown), four breaks in series are provided, all dimensions being reduced by a multiple of four, to reduce the air-pressure required. In Fig. 31 (not shown), a tank containing air at four atmospheres is provided, the circuit-interrupter preferably being similar to that shown in Fig. 8. The contacts may be crowned so that the arc is drawn near the orifice which may be circular, Fig. 17 (not shown), in the form of a slot, Figs. 11, 12 (not shown), or it may be a slot with a widened central portion, Fig. 19 (not shown). A condenser, or a condenser and resistance in shunt or series, may be shunted across the contacts. Specification 528,332, [Group XXXV], is referred to.