GB453298A - Improvements in or relating to metal-clad draw-out electric switchgear - Google Patents

Abstract

453,298. Switchgear structures. REYROLLE & CO., Ltd., A., Hebburnon-Tyne, COATES, F., Cranlea, Whitburn Road, Cleadon, Co. Durham, and CHRISTIE, J., 4, Sidecliff Road, Sunderland. June 12, 1935, No. 16915. [Class 38 (v)] In order to prevent lowering of the flashover value of an orifice insulator in metalclad, draw-out type gear, due to the accumulation of dirt or moisture on its surface or to ionization of stagnant air therein, means are provided whereby a current of clean, dry air is caused to flow through the insulator around the insulated conductor when the conductor is in its normal operative position within the insulator. The orifice insulators B2, C<2> mounted on the bases of oil or compoundfilled chambers B, C, normally house the insulating bushings D<1>, E<2> of a verticallywithdrawable circuit-breaker A, the bushings having collars D<2>, E<2> closing the lower ends of the insulators. The insulator bases have outlets B<4>, C<4> to the atmosphere and inlet passages B<3>, C<3> communicating with a pipe F into which air, filtered at G<1>, is sucked by a motor-driven fan G. The air is dried by silica gel or other hygroscopic material in a vessel H, and a hair hygrometer or other electric alarm J stops the fan if the air has too high a moisture content. The alarm J or a clock-control acting at definite intervals may serve to change over to a second vessel H, and connect the first vessel to a separate supply of heated air to dry its contents. In the isolating position of the gear, the doors closing the mouths of the insulators B<2>, B<3> are relied on to keep out dust and moisture.