GB510727A - Improvements in and relating to electric measuring instruments - Google Patents

Abstract

510,727. Supply meters. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 9, 1938, No. 4096. Convention date, Feb. 9, 1937. [Class 37] In a disc-armature induction type energy meter, or relay, the magnetic circuit is made up of one-piece laminations 10 and carries a voltage coil 12 and series-connected current coils 13-16, the coils 13, 15 on one side of the disc 11 producing substantially the same current flux as the coils 14, 16 on the other side, thereby balancing out any axial forces produced on the disc due to the current flux resulting from a current surge. The current and voltage flux distributions are shown in Figs. 3, 4 (not shown). The usual shortcircuiting coil or ring 26 for lagging the voltage flux is bent as shown so that the portions thereof located between the legs of the laminations lie also substantially in the centres of the current coils 13, 15. Overload compensation is effected, as described in U.S.A. Specification 1,727,509 by means of saturable magnetic shunts 23, 32 for the current flux and by means of a gap 29 in the current flux circuit bridged by a magnetic piece 30 separated from the magnetic core by non-magnetic spacers 31. Projections 27 on the core provide a short circuiting path for the voltage flux and serve for compensating errors due to damping of the potential flux as described in Specification 281,250, [Class 37].