GB566559A - Improvements in non-inductive electric resistors - Google Patents

Abstract

566,559. Wire resistances. BRITISH THOMSON-HOUSTON CO., Ltd., and COX, H. E. Sept. 8, 1943, No. 14698. [Class 37] A non-inductive resistor comprises a plurality of coils located in spaced circumferential grooves in an insulating former, the coils being in the form of flat spirals and wound from a continuous length of wire in the same direction, the portions of the continuous length of wire forming the connections between adjacent coils being so disposed that, when current flows in the resistor, its direc. tion in adjacent coils is opposed. The resistance is wound on a former made by threading insulating discs 4, 5, 6 or a square insulating rod 3- The flat spiral coils 7 lie between discs 4 and 6, the inner diameter of the coils being determined by the diameter of the small discs 5 whose thickness is the same as the diameter of the wire. The resistance is wound from a single length of wire on a spool, by the following method. The first coil is wound on, the outer free end being connected to terminal 14<1> and the inner end, still connected to the spool, is carried through a radial slot 8 in the next disc 6 and engaged in a notch 9. Sufficient wire for the next two coils is unwound from the spool and held out in a bight, the end next the spool being engaged in the notch 9 of the next disc 6. The former is then rotated to wind the two coils together until the bight is absorbed, the end of the bight finally straddling a peripheral notch in the disc 4 between the two coils. The rest of the coils are similarly wound in pairs and the last free end is connected to terminal 151. The upper end of spindle 3 has a metal member 12 carrying a nut 18 which serves to adjust a spring 16 which holds the coils in compression. The ends of the resistance are electrically connected to metal end plates 20, 21 sealed to an insulating tubular casing 19 which may be filled with oil.