GB401547A - Improvements in and relating to electric resistance devices - Google Patents

Abstract

401,547. Variable resistances; automatic regulation. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Thompson, L. W. ; 53, Baker Avenue, Schenectady, New York, U.S.A.) Feb. 24, 1933, No. 5718. Convention date, Feb. 25, 1932. [Class 37.] A variable resistor comprises a straight tubular casing partially filled with conducting liquid and movable about its longitudinal axis, a resistance element being mounted. in the casing and at a slight angle to the longitudinal axis, so that as the casing is rotated the longitudinal contact area between the liquid and resistance element is varied. A glass or porcelain casing 2 is carried in a frame 3, 4 mounted on knife-edge bearings 5, a resistance wire 8 being wound on a strip 9 supported between end-plates 10 and inclined slightly to the longitudinal axis of the casing, the wire making a variable contact with mercury 7 as the casing is rotated. Baffle-plates 16 supported between rods 17 are provided to break up the ripples formed on the surface of the mercury when the casing is rotated suddenly. Rotation of the casing is effected against the action of a spring 24 and a dashpot 25 with additional spring 26 is provided to smooth the action of the resistor. Voltage regulation may be effected by connecting the frame 3, 4 with a solenoid core 18, the resistor being in the shunt field circuit of a generator 21. The tension of spring 24 may be adjusted to produce under- or over-compounding effects.