Patent GB-190402098-A (GB)
Title: Improvements in Electric Induction Motor Meters.
Filed: 1904-01-27
Granted: 1904-06-23
Abstract: 2098. Compagnie pour la Fabrication des Compteurs et MatÚriel d'Usines Ó Gaz. Feb. 26, A.D. 1903, [date applied for under Patents Act, A.D. 1901]. Energy meters.- An induction motor watt-hour meter or watt-meter for a single alternating current has a conductive disc revolved by the co-operation of a highly-inductive electromagnet connected between the supply mains, and iron cores carrying maincurrent windings and closed-circuit windings to produce one or more magnetic fluxes through the disc leading in phase relatively to the main current, and exactly in quadrature to the flux produced by the pressure coils. The disc may be retarded by a permanent magnet and drive a counter, or the turning of the disc may be resisted by a spring, and caused to move a pointer over a scale. The iron cores with the main-current and closed windings are considered in the Specification as three-core transformers, a number of different arrangements being described. Fig. 2 shows one arrangement diagrammatically. Three vertical iron cores C, A, B are connected together at the top and the bottom by two yokes, and the core B may have a gap ; the revolving disc passes through this gap, and between the poles of a separate pressure electromagnet. The main current passes through windings f<0>, f<1>, f<2> such that the whole magnetic flux produced by it passes through the core C singly, and;the cores A, B in parallel. The closedcircuit secondary windings f<1>1 are such that their magnetic circuit is through the core A singly, and the cores C, B in parallel. In a modified arrangement, one core of the transformer is omitted, either the main or the secondary magnetic circuit being completed through air ; the windings of the remaining cores are increased or diminished to compensate for the omission of the windings of the omitted core. For this purpose, some of the windings may be passed round both the remaining cores. In a third arrangement, the cores C, A, Fig. 2, carry equal main-current windings, while the third core carries a secondary winding only the core C may be without a secondary winding. A fourth arrangement has windings as in Fig. 2, but, instead of the secondary windings being in a closed circuit, they are connected in parallel with the main windings. In a fifth arrangement, the three-core transformer is included bodily in the magnetic circuit of the pressure electromagnet. The transformer may be arranged to give no magnetic potential difference between its yokes, in order to avoid mutual induction between the pressure coils and the other windings. Or two three-core transformers may be included symmetrically in the magnetic circuit of the pressure electromagnet, one or two cores of each transformer having gaps to receive the revolving disc ; the effects of the two transformers may thus balance with respect to the pressure circuit, or not, and resistance may be connected in series with the pressure coils, or in the closed secondary circuits, to regulate the phase displacement of the effective magnetic fluxes. Fig. 17 shows a construction in which one core of each transformer is omitted, the remaining pairs of cores A, B and B', A' being carried near together by the poles of the pressure electromagnet P, over one side of the rotary disc D. The magnetic circuits are completed through an iron block R, secured in guides on a non-magnetic support Q by screws ; a laterally-adjustable block S is also provided. The main-current windings are shown connected to terminals b<1>, b<6> ; the secondaries are conductive rectangles 7, 10 surrounding the pairs of cores. The vertical spindle of the disc D rests normally on a jewel in a vertical screw stud. For transport of the meter this stud is inverted in a horizontal support, and used to hold up the spindle so that the disc D bears against the brake magnet.