GB390822A - Improvements in or relating to signalling conductors - Google Patents

Abstract

390,822. Cables. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Gilbert, J. J. ; 16, Pine Street, Douglaston, New York, U.S.A.) Oct. 9, 1931, No. 28137. Convention date, Oct. 30, 1930. Addition to 339,968, [Class 36, Electricity, Conducting &c.] [Classes 36 and 37.] In a cable composed of core lengths twisted together and so chosen that the electrical properties of the lengths in a pair are nearly equal, as described in the parent Specification, the lengths are matched for the longitudinal inductance component described in Specification 206,104, [Class 36, Electricity, Conducting &c.], as well as for other properties. To enable this to be done the core length 10 is wound from a reel 20 to a reel 21, passing on its way through a coil 30. The reels 20, 21 are mounted on insulated stands 22 and connected to the ends of the core length, so that a current can be passed through it by means of a battery 24, and interrupted as required by a key 25. The currents induced in the coil 30 in consequence of the longitudinal component in the induction can be read on a ballistic galvanometer 35, or by means of a flux-meter 20 which can be connected to the coil 30 through an amplifier 37. The longitudinal component of the inductance can then be plotted along the length of the core and two portions showing similar curves combined. Instead of measuring the component for a single core two cores may be twisted together and their combined component measured ; two pairs giving similar results are then combined to form a quad.