GB190205010A - Improvements in Electric Meters. - Google Patents

Abstract

5010. Blanchet, A. Feb. 27. Energy meters.-In an alternating-current induction motor meter, having a rotary conductive cylinder or disc A acted on by current and pressure coils B<I>, BE, the magnetic fluxes in these are put in quadrature, when the main current and pressure are in phase, by making the circuit of the pressure coil BE highly inductive, and supplying the current coil B<I> from the secondary of a small transformer T', the primary of which is in the main circuit. In the form shown, the current and pressure coils are provided with two-pole iron cores b, d, placed at right-angles to each other, the magnetic circuits being completed through a stationary laminated iron armature C, below the rotary disc A. The disc is retarded by permanent magnets M<2>, and its spindle drives a counter. The time-constant of the secondary circuit of the transformer T' is made equal to that of the pressure coil BE, by adjusting either the height of the stationary armature C, or a resistance R<1> in the secondary circuit, or a resistance R<3> closing the circuit of a third winding on the transformer, or an air gap in the magnetic circuit of an inductance coil in circuit with the pressure coil. To obtain a starting effect independent of the main current, a winding E' on the core b is supplied with current from a secondary winding provided either on the core d of the pressure coil B<E>, or on the core of an inductance coil in circuit with the pressure coil ; or the winding E' may be placed in a non- inductive shunt circuit of high resistance. The same effect may be obtained by providing an adjustable laminated iron plate above the disc A, to shunt a part of the magnetic flux of the pressure coil BE. In a modified arrangement, the coil BE and core d are replaced by two coils on rectangular cores with small air-gaps through which the disc travels ; the two cores are constructed as extensions of the rectangular core of the transformer T', which is placed below the disc A. In another arrangement, the current and pressure coils B<I>, BE are vertical solenoids acting directly on the disc A, without iron cores. For three-phase currents, two sets of coils are arranged to act on two conductive discs or cylinders carried by a single spindle.