GB173291A - Improvements in electric resistances - Google Patents

Abstract

173,291. Crompton & Co., Ltd., and Jones, W. F. Sept. 22, 1920. Wire and ribbon resistances, embedded.-Non- inductive resistances wound as described in Specification 130,137, [Class 83 (iv), Metals, Working], are embedded in insulating and refractory cement and are clamped between flat metal plates which are coated on their inner sides with silicate enamel and are riveted or bolted together. The cement may be composed of four parts ground steatite, one part ground silica quartz, and oneseventh part asbestos wool, mixed to a thick paste with silicate or soda and water at a sp. gr. of 1.24. Fig. 1 shows a rectangular grid resistance, and Figs. 4 and 5 show a circular grid resistance arranged as a rheostat, the metal plates B, C being connected together in each case by rivets D. The ends of the grid wires A, Fig. 1, may be secured to metal terminals E preferably by silver solder. The plates B, C are cut away as shown at GG where the terminals E protrude, and insulation HH e.g. of mica is inserted. Alternatively, the ends of wires A are secured to terminal wire loops K, L, Fig. 14, each passing through an insulating bead M supported in a bellmouthed portion of the plates B, C. The grid, Fig. 1, may be supported by insulated rods at F, on which they are retained in position by pivoted clamps G, Figs. 1 and 17, having their free ends J bent inwards to grip the plates B, C. For connecting the ends R of the grid wires A of the rheostat, Fig. 4, to the contacts or terminals, the wire is passed along a groove P in the shank of the contact or terminal and is secured by a nut S, Fig. 7, or by a screw clamp T, Fig. 9.