GB1284385A - Electric resistance heating cable - Google Patents

Abstract

1284385 Electric resistance heating cables PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 7 July 1970 [10 July 1969 26 June 1970] 32880/70 Heading H5H In a heating cable of the type comprising a flexible insulating core 1, a wound heating wire 2 and an insulating covering 8, and which has at leat two sectors A and B required to assume different temperatures during operation, the sector B which is to be the low temperature sector has an odd number (3) of helically wound layers of heating wire, in contact with one another and wound alternately in opposite directions, and the sector A which is to be the high temperature sector has at least two less such layers, e.g. one layer as shown. In sector B, the first two layers 3, 4, and 5, 6, have a pitch approximately 20 times greater than the third layer 7, which has the same pitch as the single layer of sector A. Core 1 is of glass fibre, optionally including a central conductor 10, Fig. 2 (not shown), and the outer covering 8 is a glass fibre pleat or spinning. Other possible core materials are P.V.C., silicone rubber, nylon, asbestos fibre, P.T.F.E. or polyfluoroethylene propylene. The heating wire is of nickel or copper. The outer covering may be provided by winding and/or pleating with glass or asbestos fibres or rayon or cotton, or by extruding a synthetic resin covering. Optionally the outer covering is a plurality of apertured ceramic bodies. The heating cable has application in heaters for hair curlers, comprising hollow cylinders projecting from a bottom plate on to which the curlers can be slid. Other applications are to defrosters for refrigerators. Terminals for the cable are described, Fig. 2 (not shown).