Patent GB-676693-A (GB)
Title: Improvements relating to direct current measuring, indicating, and control circuit arrangements
Inventor: WILSON JOSEPH SHEVLIN
IPC: G01R27/12
Filed: 1949-04-08
Abstract: 676,693. Current, voltage and power measurements. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. May 26, 1950 [April 8, 1949; Nov. 18, 1949], Nos. 9632/49 and 29593/49. Class 37. [Also in Group XXXVIII] In an electrical measuring circuit one of the operating windings of an A.C. wattmeter or integrating watt hour meter is energized through the output winding of a transductor, whose control winding is excited by a D.C. representing a physical or electrical quantity to be measured or integrated with respect to time. Both meter windings may be energized from corresponding transductors respectively excited by D.C.'s representing plural quantities to be measured in correlation, or the outputs of several transductors may be combined in a multi-wound transformer exciting a single meter winding, or the individual transductors may have plural D.C. control windings. In Fig. 1 the conducting disc 1 of an induction type integrating or indicating meter M is rotatable between the poles of electromagnets 2, 3 having windings 4, 5 which are respectively energized from an A.C. line 6, 7 through the output windings of transductors T1, T2 whose control windings 12, 13 are respectively energized with direct currents representative of independent electrical or physical quantities. If the meter disc rotates continuously against magnetic damping its total rotation measures the integral of the product of the unknown quantities with respect to time, while if it rotates against a restoring spring the magnitude of the product is indicated. In Fig. 3 the meter coils are energized by the outputs of transductors T1, T2 whose control windings are energized respectively by the rectified A.C. outputs of a known inductor device 23 having an A.C. energized stator 24 and a rotor 22 deflected by a movable roller 27 responsive to the sag of a conveyer belt 20, and of an A.C. energized tachometer generator 31 rotated by the conveyer drive. The meter M' thus indicates the rate of passage of material on the belt, or the total weight conveyed. In Fig. 4, the control currents of the transductors T1, T2 energizing the meter windings are respectively derived from the voltage and current of a D.C. supply line 40, 41 whose instantaneous or integrated wattage is indicated by the meter. Resistance 4a across meter coil 4 ensures the appropriate phase difference between the windings for maximum torque. In Fig. 7, the coils 5, 5<SP>1</SP> of two meters M, M<SP>1</SP> are energized in series by a transductor T2 responsive to the current in a D.C. line 40, 41 while the coils 4, 41 are energized by transductors T1, T1<SP>1</SP> controlled through rectifiers 47, 48 by the line voltage, and since the rectifiers are oppositely poled one meter indicates the forward and one the reverse instantaneous or integrated power in the line. In Fig. 9, a D.C. line 56 supplies feeders F1, F2, F3, and their respective currents control transductors T21, T22, T23 energizing the windings 51, 52, 53 of a transformer CT, whose secondary energizes the coil 5 of the meter M, whose coil 4 is energized by a transductor T1 controlled by the line voltage, so that the meter indicates the total instantaneous or integrated power in the feeders. ! In other modifications the meter windings may be energized from a stabilized A.C. source and from a single transductor controlled by a direct current whose instantaneous or integrated value is indicated, Fig. 2 (not shown) ; transductors controlled by the outer conductor voltages and currents of a 3-wire main respectively energize the four windings of a double disc meter indicating the total instantaneous or integrated power, Fig. 5 (not shown) ; corresponding windings of two meters respectively indicating the normal and reverse power in a D.C. line are energized in series by a currentcontrolled transductor while the other windings are alternatively energized by a voltage controlled transductor through the contacts of a relay responsive to the direction of power flow, Fig. 6 (not shown) ; one meter winding is energized from an A.C. source and the other from' a transductor controlled by the currents in plural feeders, to indicate the total instantaneous or integrated current, Fig. 8 (not shown) ; or the voltages and currents in plural feeders may respectively control pairs of transductors energizing the windings of corresponding meters to drive known impulsing transmitters to operate a summating meter indicating the total instantaneous or integrated power, Fig. 10 (not shown). The modifications applicable to plural feeders may be used to indicate the instantaneous or total weight of material traversing a conveyer belt. The meter movement may operate a relay.