Radian Research, Inc.

Duncan Electric Company, Inc.

Glenn A Mayfield

Shannon Edwards

Matthew Eric Kraus

David A Bobick

Richard R Webeck

Kevin L Stricker

Robert L Straw

William A Szabela

David D Gloyeski

Glen R Phillips

William L Vollmer

Mark M Forbes

Russell F Greafnitz

Robert E Brandyberry

A method and apparatus for testing a transformer. A controller generates a switching signal and supplies the switching signal to a solid state switch in circuit with a test load of known magnitude, switching the solid state switch to place the test load in circuit with the transformer. A signal through or across the transformer is then measured. Methods and apparatus for testing a transformer comprise the controller and solid state switch placing a series of test loads of different known magnitudes in circuit with the transformer from the lowest magnitude to the highest, from the highest to the lowest, or both. Additionally, a test load array comprises a plurality of power resistors, a heat sink for accommodating the plurality of power resistors, and a material providing electrical insulation of the power resistors from the heat sink and thermal conductivity between the power resistors and the heat sink.

Instrument transformer test equipment and method

A transformer includes at least two magnetically coupled cores with a common axis. The cores have cross sectional configurations transverse to the common axis which are not rectangular. An exciting voltage is to be applied across a first winding provided on one of the cores. A second winding provided on one of the cores includes first and second terminals across which a voltage is to be induced in response to the exciting voltage. A first device provides a relatively higher impedance between the first and second terminals of the second winding. The first device is coupled between the first and second terminals. Third, fourth and fifth windings have respective first and second terminals. The third and fourth windings are wound on one of the cores with a first polarity. The fifth winding is wound on one of the cores with a second polarity opposite to the first polarity. A second device provides a relatively higher impedance between the terminals of at least one of the third winding; the fourth winding; and, the fifth winding. One terminal of each of the second, third, fourth and fifth windings is adapted for coupling to a relatively lower impedance.

Transformers

A transformer includes a first winding and a second winding coupled to the first winding through a magnetic circuit so that current through the first winding induces a voltage across the second winding. The first winding includes n separate shield portions, where n is an integer. Each of the n shield portions shields only a corresponding portion of the first winding. Each of the n shield portions is electrically coupled to the adjacent shield portion(s) substantially only through its coupling to the first winding, the first winding, and the other(s) of the adjacent shield portion's (s') coupling(s) to the first winding.

Reduction of capacitance effects in potential transformers

A transformer includes taps by which electrical contact can be made to winding sections of the transformer at locations along its length between its end terminals. A first switch permits contact to be made selectively to a selected one of the taps. An amplifier has an inverting input terminal, a non-inverting input terminal and an output terminal. The output terminal of the amplifier is coupled to the first switch so that selectively making contact with one of the taps couples the selected tap to the output terminal of the amplifier.

Wide ratio autotransformer-type current ranging

A method and apparatus for analog-to-digital (A/D) converting an input signal having a first polarity include providing an integrator including a capacitance coupled to an input port of an amplifier, coupling an A/D converter to an output port of the amplifier, changing the amount of charge stored in the capacitance by coupling the input signal and a reference source having a second and opposite polarity to the capacitance, and controlling an A/D conversion cycle of the A/D converter to simultaneously charge and discharge the capacitance with the input signal and the reference source prior to each A/D conversion cycle. Another method and apparatus for (A/D) converting an input signal include providing an integrator including a capacitance coupled to an input port of an amplifier, coupling an A/D converter to an output port of the amplifier, changing the amount of charge stored in the capacitance at a known time rate by alternately coupling the input signal and a reference source to the capacitance through at least one switch, and controlling an A/D conversion cycle of the A/D converter and the at least one switch for controlling the coupling of the input signal and the reference source to the capacitance.

Methods and apparatus for analog-to-digital conversion

A transformer having a primary winding and a secondary winding across which load is coupled is compensated. A third winding is provided on the transformer. A first output terminal of an amplifier is coupled to a first terminal of the primary winding. A first terminal of the third winding is coupled to the second terminal of the primary winding. A second terminal of the third winding is coupled to an input terminal of the amplifier.

Compensated transformers

A system for increasing the voltage handling capacity of an amplifier circuit coupled to a transformer output comprises a transformer secondary winding divided into n sub secondary windings, where n is an integer. A first terminal of a first of the sub secondary windings is coupled to a reference potential. n amplifiers, numbered sequentially 1.ltoreq.m.ltoreq.n as they appear in the amplification circuit with an output terminal of the nth amplifier comprising an output terminal of the amplification circuit, each have an input terminal and an output terminal. An input terminal of the first amplifier is coupled to a second terminal of the first sub secondary winding. An output terminal of each of the n amplifiers is coupled to a first terminal of the next adjacent higher numbered sub secondary winding, except for the nth amplifier, the output of which comprises the output of the amplifier circuit. A first voltage supply is coupled to the first amplifier to provide operating voltage to the first amplifier, and to reference potential. n-1 additional voltage supplies are coupled to respective ones of the n-1 remaining amplifiers to provide operating voltage thereto, and to the output terminal of the next adjacent lower numbered amplifier.

Amplifier circuit with increased voltage handling capacity

A Programmable Demand Register (PDR.TM.) which has a multi-function externally programmable time based measuring system is disclosed. An optical communication port is provided for bidirectional communication of data, said meter being capable of recordation of energy consumption in several different modes, according to the decision of the meter programmer. Meter programming is accomplished by means of any one of three separate devices, namely a Programmer/Reader (P/R) which is a sophisticated computerized device fully adapted to reprogram the PDR.TM. to function in any one or combination of modes as desired, to both receive and store data, and to output said data to a central billing recordation computer, and a billing period resetter (BPR) which is a battery powered device also adapted for two way communication, but limited to resetting the BPR as to data in the BPR memory, but not as to mode of operation of the BPR, and an inexpensive lightweight BPR-1 which also has two way communication capabilities, but limited to resetting the various meter functions, after insertion of a manually programmed password by the actuation of a series of switches.

Programmable demand register with two way communication through an

A Power Transducer is disclosed, such as a watt-watthour Transducer, having a dual multiplier circuit receiving inputs from a power source to be monitored and a triangle wave generator. The circuit includes first and second transformers which separately receive voltage and current inputs representative of the power line to be monitored. The first transformer provides dual outputs of opposite polarity which are isolated and scaled replicas of the input voltage. The dual outputs are separately channeled through half-wave multiplier paths, to a comparator in each path, which comparators receive the input from the triangle wave generator to produce a pulse modulated output for control of a switch in each path, which switches also receive the current signal from the second transformer. The outputs from the switches have pulse heights proportional to the instantaneous value of the current and pulse widths proportional to the incoming voltage with the integral being equal to the product of the voltage and current. The combined switch outputs are filtered to remove the chopping frequency and then coupled to a load.

Power transducer

Transducers of the average responding RMS indicating type are disclosed that are particularly useful for monitoring currents and voltages in a power distribution network. The transducer includes transformer, inductively compensated voltage divider, active filter and output amplifier circuits electrically connected to provide a transducer having excellent long term transducer stability so that the transducer requires no calibration, and a highly accurate readout over a wide temperature range.

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West Lafayette, IN, United States of America

Glenn A Mayfield