Abstract: A device and method for more accurately measuring power consumption in a residential application without having to make connections to high voltage sources in a distribution panel. Since the device calculating the power consumption generally needs to be powered to perform its functions (e.g., plugged into wall outlet), the disclosure utilizes the power supply as a voltage source for measuring voltage without having to make connections to the panel.

Abstract: A computer system includes at least one system component including a first realtime clock that produces interrupt requests, at least one power supply unit that supplies the system component with at least one operating voltage, wherein the power supply unit includes at least one microcontroller having a second realtime clock, and at least one firmware component, wherein the firmware component transfers programming of the first realtime clock to the second realtime clock before the computer system changes to a switched-off state or an energy-saving state.

Abstract: Described is an analog to digital converter (ADC) which comprises: a sigma-delta modulator to receive an analog signal, the sigma-delta modulator operable to perform chopping to cancel common-mode noise; and one or more counters coupled to the sigma-delta modulator to generate a digital code representative of the analog signal.

Abstract: Power measurement by tracking of a voltage cycle when voltage and current measurements are taken at different locations on an AC power line, with the devices taking the measurements interconnected by an asynchronous data network. In general, a synchronization/timing message is sent from the voltage sensing side to the current sensing side, with the synchronization/timing message being transmitted at a predetermined point in the periodic voltage cycle. The receipt of the synchronization/timing message by the current sensing side may be used to re-synchronize an internal model of the voltage cycle maintained by the current sensing side to the measured voltage cycle. The predetermined point in the voltage cycle may be the zero-crossing point, or other point, of the voltage cycle.

Abstract: An embodiment of a system includes a utility meter having an enclosure, a first component and a second component in the enclosure, and a mounting assembly configured to couple the first and second components together in the enclosure. The mounting assembly includes a first mount having first and second prongs disposed about an intermediate space, a second mount configured to extend bi-directionally into the intermediate space between the first and second prongs in opposite first and second directions, and a snap-fit fastener. The snap-fit fastener includes first and second snap portions configured to bi-directionally engage one another in the opposite first and second directions to secure the first and second mounts.

Abstract: An integrated device suspended at a high voltage potential for the metering and protection of a distribution network comprises a measurement current transformer (CT), a protective CT and a voltage sensor. The voltage signal is output from the voltage sensor to an electric energy metering module and first and second electric signal acquiring modules. The current signal acquired by the measurement CT is output to the electric energy metering module. The current signal acquired by the protective CT is output to the first and second electric signal acquiring modules. The electric energy metering module processes the current and voltage signals and sends the processed data to a comprehensive control module. The first and second electric signal acquiring modules send the voltage and current data to the comprehensive control module. The comprehensive control module comprehensively calculates the received data and sends the result to a low voltage terminal.

Abstract: The disclosure relates to a meter for monitoring usage of power provided by a power transmission system to a site. The meter comprises: a meter module connected to a power feed associated with the power transmission system to provide readings relating to the power; a messaging module to provide messages to the power transmission system; a connection to an alternating current (AC) power supply; a rectifier circuit connected to the AC power supply to generate a direct current (DC) power signal; a capacitive circuit connected to an output of the rectifier circuit, the capacitive circuit including a capacitor for storing a voltage for temporarily providing replacement power for the rectifier circuit; and a switching regulator circuit connected to the output of the rectifier circuit and the capacitive circuit, the switching regulator converting the DC voltage signal to a stepped down voltage signal for the meter module.

Abstract: Systems and methods for determining possible theft scenarios at utility meters are described. In some examples, the system receives information that indicates possible tampering of utility meter by a customer of a utility. In some examples, the system uses the information to determine a theft scenario. The system may then use the determined theft scenario as evidence against the customer.

Abstract: A characteristic of a first utility meter is detected with a first probe head, and a characteristic of a second utility meter is detected with a second probe head. The characteristic of the first utility meter is dependent on a usage of a first utility metered by the first utility meter, and the characteristic of the second utility meter is dependent on a usage of a second utility metered by the second utility meter. Information related to the characteristic of the first utility meter is communicated from the first probe head to a communication unit, and information related to the characteristic of the second utility meter is communicated from the second probe head to the communication unit. A message is also sent from the communication unit indicating the usage of the first utility or the usage of the second utility.

Abstract: Some embodiments relate to a system for measuring power produced by a power source. The system includes a first voltage sensor for sensing a first voltage difference between a first voltage and a second voltage and a second voltage sensor for sensing a second voltage difference between a third voltage and the second voltage. The system further includes a first current sensor for sensing a current difference between a first current and a second current, and a second current sensor for sensing a current difference between a third current and the second current. The system further includes a power measuring device that determines the power produced by the power source using the first and second voltage differences and the first and second current differences.

Abstract: An intelligent electronic device for monitoring and determining an amount of electrical power usage by a consumer, or end user, and for providing broadband Internet access to the consumer. The intelligent electronic device includes at least one sensor coupled to an electric circuit configured for measuring at least one power parameter of the electrical circuit and generating at least one analog signal indicative of the at least one power parameter; at least one digital to analog converter coupled to the at least one sensor configured for receiving the at least one analog signal and converting the at least one analog signal to at least one digital signal; a processor configured for receiving the at least one digital signal and calculating energy consumption in the electrical circuit; and a gateway configured for receiving data transmissions imposed on the electrical circuit and for demodulating the imposed data transmission for providing data communications.

Abstract: A device for sensing electrical current or voltage in an electrical distribution system using an actively compensated current ratio transformer that includes a first magnetic core having a first permeability and a second magnetic core having a second permeability higher than the first permeability. A primary winding having P turns is coupled with the first and second magnetic cores, a measurement winding having M turns is coupled with the first and second magnetic cores so that current in the primary winding induces current in the measurement winding, and a sense winding having S turns is coupled with the second magnetic core. An amplifier coupled to the sense winding receives a voltage developed across the sense winding and produces a compensation current in response to the received voltage. The amplifier has an output coupled to the sense winding to feed the compensation current through the sense winding to reduce the voltage developed across the sense winding voltage to substantially zero.

Abstract: A combined current transformer and metering system is described, having a securable case, two or more current transformers each having a core and secondary windings connected to a secondary circuit, wherein the transformers are mounted within the case. A wiring harness connects the secondary windings of the transformers with shorting current switches for short circuiting the secondary current circuit, and voltage switches for disconnecting a voltage, wherein both sets of switches are mounted on the case. A process of manufacturing the system is described, wherein the transformer cores are positioned within the case, the wiring is connected between the transformer cores and attachment hardware on an upper deck of the case, and insulation medium is inserted within the case. A base plate is described, having rails to hold the system and having a tab at one end, and apertures for a rod positionable between rails at a second end.

Abstract: This disclosure relates to a three-phase electric energy measurement apparatus, comprising: a voltage detection unit for detecting voltage of each phase in power transmitting lines where the voltage detection unit is; a current detection unit for detecting current of each phase in the power transmitting lines where the current detection unit is; an electric energy calculation unit, connected to said voltage detection unit and said current detection unit, for receiving signals outputted from said voltage detection unit and said current detection unit, and performing signal processing and calculation, and then outputting a calculation result; wherein both said voltage detection unit and said electric energy calculation unit are connected in a star connection mode, forming a common virtual ground. Through the above-mentioned grounding manner different from that in the prior art, a three-phase four-wire electric energy meter is formed using a three-phase three-wire connection method.

Abstract: Disclosed herein is an approach that uses a wattmeter to determine hydraulic fluid parameters. In one aspect, a controller uses the electric power measured by the wattmeter to determine the power delivered to hydraulic fluid delivered by a hydraulic pump unit to a hydraulic fluid consuming device and the volumetric flow rate of the hydraulic fluid delivered to the hydraulic fluid consuming device by the hydraulic pump unit.

Abstract: An integrated galvanically isolated meter devices and method for making integrated meter devices are disclosed. An embodiment of an integrated meter device includes a carrier, a control chip disposed on the carrier, a first measuring device chip disposed on the carrier, the first measuring device chip galvanically isolated from the control chip and configured to measure at least one first parameter of a first wire of a power line and a package encapsulating the control chip and the first measuring device chip.

Abstract: Aspects of the disclosure provide method and apparatus for detecting attributes of an input power supply. The method includes receiving a first signal generated based on a second signal that is predictive. The first signal includes a portion that substantially corresponds to the second signal. Further, the method includes detecting attributes of the portion of the first signal that substantially corresponds to the second signal, and determining attributes of the second signal based on the attributes of the portion of the first signal that substantially corresponds to the second signal.

Abstract: A system and method of dynamically estimating the short circuit current availability (SCCA) at a node in an alternating current electrical distribution system by examining the spectral composition of current drawn by a direct current charging circuit connected to the node. A correlative relationship between the total harmonic current distortion (THDi) in the current drawn by the charging circuit and the SCCA at the node is established for a particular charging circuit. An estimation of the SCCA at the node is accomplished by taking current measurements of current drawn by the charging circuit, analyzing those current measurements to determine the THDi, and estimating a corresponding value of SCCA based on the determined THDi. A method is also provided for calibrating a particular charging circuit to have a reactance and resistance suitable for use in estimating SCCA.

Abstract: A device to measure a passive intermodulation (PIM) creating component is provided that uses minimal average power. For a PIM measurement, two separate signals F1 and F2 are generated to simulate signals, such as from two different types of cell phone operating bands being transmitted in the same area or two different transmit frequencies within one cell phone operating band. PIMs are measured to assure interference is not created on one of the cell phone bands. Minimal power is used by connecting pulse width modulators (PWM) to provide DC power to the high power amplifiers (HPA) creating the signals F1 and F2. By controlling the duty cycle of the PWM to limit ON time of the HPAs to approximately 10%, significant average power savings occur. Size is also reduced with reduced power consumption because heat sinks and other cooling components are not required.

Abstract: Systems and methods for detecting the removal of a meter cover are provided. For example, a tamper-detect energy meter may include metering circuitry, a processor, a tamper detect switch, and a cover with a switch interface surface. The tamper detect switch may be triggered from an open circuit state to a closed circuit state as the switch interface surface of the cover contacts the tamper detect switch during removal.

Abstract: An instrument transformer for measuring properties of electricity in a power line is provided. The instrument transformer includes a cover section releasably secured to a base section. The cover section includes a first core segment encapsulated in a first encasement formed from a polymer resin. The base section includes a second core segment with a low voltage winding mounted thereto and a voltage transformer, all of which are encapsulated in a second encasement formed from a polymer resin. When the cover section and the base section are secured together, the first core segment adjoins the second core segment, thereby forming a current transformer having a core formed from the first and second core segments. A method for making the instrument transformer includes the connection of the cover section to the base section to form a passage through which a high voltage conductor may extend.

Abstract: A kilowatt-hour meter with remote environment detect and control is provided. Besides calculating and display a quantity of used electricity through the kilowatt-hour meter, the kilowatt-hour meter with remote environment detect and control can also perform remote data collection and environment detect and control through an Ethernet. A plurality of the kilowatt-hour meters with remote environment detect and control can be connected through network connection, so as to detect and control situations related to safety of using electricity such as over current warning, environment state, access control, etc., for prompt processing.

Abstract: A capacitor charging circuit is provided in a utility meter. The utility meter includes a measurement circuit configured to provide consumption data, a memory configured to store the consumption data from the measurement circuit, and a communications device configured to transmit the consumption data to a remote location. The utility meter also includes a power supply configured to supply an unregulated DC voltage and a regulated voltage within the utility meter. The regulated DC voltage is output from a voltage regulator and is provided to the measurement circuit. The unregulated DC voltage is supplied to the communications device. The capacitor charging circuit is configured to charge a capacitor with the unregulated DC voltage when the regulated DC voltage is provided to the charging circuit from the voltage regulator. The capacitor charging circuit may be a supercapacitor charging circuit.

Abstract: An intelligent electronic device having a terminal assembly for coupling the IED, e.g., a revenue meter, to a meter mounting socket. The assembly includes a housing including a generally planar, rigid base, the base including at least one opening and at least one circuit board having at least one electrically conducting terminal surface mounted thereon, the at least one electrically conducting terminal extending through the at least one opening of the base to mate with at least one matching jaw of a detachable meter mounting device coupled to the electrical circuit.

Abstract: A utility meter cover and complementary base are disclosed, the cover including a window section and a shroud. The shroud is for covering a complementary portion of a meter base, and includes: a radially extending base portion; an axial extension extending from the base portion, the axial extension for obstructing access to the complementary portion of the meter base; and a key member extending axially from the base portion, the key member having a bidirectional tab for engaging a slot in the complementary portion of the meter base.

Abstract: According to one aspect, embodiments of the invention provide a system for monitoring a plurality of circuit branches, the system comprising a plurality of current sensors, each configured to be coupled to at least one of the plurality of circuit branches and to produce a signal having a level related to a current level of the one of the plurality of circuit branches, a communications bus, a plurality of sensor circuits, wherein each one of the plurality of sensor circuits is configured to convert the signal from the associated one of the plurality of current sensors to a digital measurement signal and provide the digital measurement signal to the communication bus, and a controller configured to receive the digital measurement signal from each sensor circuit over the communication bus and transmit data related to the digital measurement signal from each sensor circuit to an external client.

Abstract: According to one aspect, embodiments of the invention provide a system for monitoring a plurality of circuit branches coupled to an input line, the system comprising a communication bus, a plurality of sensor circuits, each configured to be coupled to the communication bus and at least one of the plurality of circuit branches, wherein each sensor circuit is further configured to sample current in the at least one of the plurality of circuit branches, a controller configured to be coupled to the communication bus and the input line; wherein the controller is further configured to sample voltage on the input line, and wherein the controller is further configured to synchronize, via the communication bus, current sampling performed by the plurality of sensor circuits with the voltage sampling performed by the controller.

Abstract: A measuring system contains a signal generator and at least one power meter. A device under test is supplied with a signal from the signal generator. A signal output by the device under test can be measured by the first power meter. In this context, the signal generator and the power meter are connected by a bidirectional communications link.

Abstract: The present invention relates to an electric power monitoring device, and particularly to an electric power monitoring device for monitoring a quality of alternating current power. According to an embodiment of the present invention, an electric power monitoring device is provided with a first connection portion, a second connection portion and a cable that connects the first connection portion to the second connection portion and comprises a measuring unit for measuring alternating current power quality; a processing unit which is connected to the measuring unit to convert the measured power quality to data; and a display which is connected to the processing unit to display the data on a screen. The electric power monitoring device is used for an apparatus having an alternating current power input unit.

Abstract: A power detecting apparatus detects electrical power consumed by a load by multiplication of voltage information detected by a voltage detecting unit and current information detected by a current detecting unit. The power detecting apparatus includes: a switching unit including a single pole double throw relay that switches between a first circuit, in which a current flows through both of the voltage detecting unit and the current detecting unit, and a second circuit, in which a flow of a current to the voltage detecting unit is interrupted and a current flows through a bypass path to bypass the current detecting unit; and a control unit that performs control to switch to the first circuit when the power detection is to be performed, and control to switch to the second circuit when the power detection is not to be performed.

Abstract: A tool for configuring a branch current monitor facilitates mapping the connections of branch circuits to voltage sources in a power distribution panel.

Abstract: In a method for current measurement in a multiphase current network, a conductive connection is produced between a plurality of the phases of the multiphase current network such that the plurality of the phases is short-circuited with one another. At a detection time, a current value flowing between the conductive connection and a first voltage potential is detected.

Abstract: A system for monitoring power in accordance with the present disclosure has a first transformer monitoring device that interfaces with a first electrical conductor electrically connected to a transformer at a first location on a power grid. The first transformer measures a first current through the first electrical conductor and a first voltage associated with the first electrical conductor. In addition, the system has a second transformer monitoring device that interfaces with a second electrical conductor electrically connected to the transformer. The second transformer measures a second current through the second electrical conductor and a second voltage associated with the second electrical conductor. Further, the system has logic configured to calculate values indicative of power corresponding to the transformer based upon the first current and the first voltage and the second current and the second voltage.

Abstract: In embodiments of the present invention, a method and system is provided for designing improved intelligent, LED-based lighting systems. The LED based lighting systems may include fixtures with one or more of rotatable LED light bars, integrated sensors, onboard intelligence to receive signals from the LED light bars and control the LED light bars, and a mesh network connectivity to other fixtures.

Abstract: A system and method of monitoring a plurality of electrical assets comprise an electricity distribution infrastructure, including a plurality of electrical asset sensors coupled to the electrical assets for monitoring an operating condition of the electrical assets as well as any fault conditions. The sensors may include a current transformer for obtaining a current waveform, a GPS receiver for applying a synchronized time-stamp to the waveform data, and a mesh network radio for transmitting the time-stamped waveform data. Data from the plurality of sensors may be encrypted and transmitted over a mesh network to one or more gateways that are in communication with a central command processor. In response to an abnormal operating condition of any electrical asset, the central command processor may determine a probable fault location, a probable fault type, and a fault response.

Abstract: Methods, devices and systems of phase identification for a meter. One aspect includes a method of phase identification for a smart meter. One embodiment of the method includes connecting a device to at least a first phase of a poly-phase electrical system; metering at least the first phase of the poly-phase electrical system that the device is connected to for electrical consumption information using a meter; storing a first phase identifier for the first phase of the poly-phase electrical system that the device is connected to in a memory associated with the meter; and transmitting at least the first phase identifier over a network operably connected with the meter.

Abstract: An electricity meter comprises a single current sensor with a toroidal coil that has an inner bore extending substantially through the sensor. The meter also has two current conductors that form one of a pair of line-side blades of the meter. The electricity meter also has a disconnect switch with a pair of moveable contacts and a pair of fixed contacts. One of the pairs contacts is electrically connected to the current conductors. The other pair forms a respective load-side blade of the meter. One current conductor passes through the inner bore of the current sensor in a first direction relative to its line-side blade and the other current conductor passes through the inner bore of the current sensor in a substantially opposite direction relative to its line-side blade so that current passing through the conductors passes through the inner bore of the current sensor in a same direction.

Abstract: A precision charge dump circuit configured to transfer preset quanta of charge to or from a first capacitor (for example, an integration capacitor in an in-pixel ADC circuit). In one example, the charge dump circuit uses a second capacitor that is pre-charged with the preset quanta of charge to determine the preset value of the quanta of charge, and an amplifier in a voltage-follower mode to cause the charge subtraction or addition.

Abstract: An intelligent electronic device (IED), e.g., an electrical power meter, having wireless communication capabilities, e.g., Bluetooth connectivity, for transmitting and receiving data without a hardwire connection is provided. A system and method for retrieving revenue metering data from at least one IED, e.g., a revenue meter, are also provided. The system includes at least one intelligent electronic device including a transceiver configured for receiving calculated energy consumption data from a processor and transmitting the calculated energy consumption data via a spread-spectrum frequency hopping technique; and a data collection device configured for receiving the calculated energy consumption data from the at least one intelligent electronic device in response to supplying a pairing passkey to the intelligent electronic device.

Abstract: A power meter having fault tolerance enhances the monitoring of electrical power by increasing the reliability of data output by the power meter having fault tolerance. The power meter having fault tolerance may enhance the monitoring process by transitioning from a faulty power monitoring device to a non-faulty power monitoring device without losing or corrupting power management data.

Abstract: An electrical circuit tester including a resistive load and a testing station for detecting the variable load. The testing station includes at least one electrical current transducer capable of detecting the variable load in an adjacent electrical power circuit. The detection of the variable load is communicated to the testing station and a variable load detection function.

Abstract: The present invention relates to a signal converting apparatus of a power metering system, a power metering system and a method for signal-converting in a power metering system. In accordance with one embodiment of the present invention, there is proposed to a signal converting apparatus of a power metering system including a frequency shift unit for shifting a frequency(s) of at least one signal of sensed current and voltage signals by a shift frequency(s) so that the current and voltage signals have different frequency bandwidths, a signal coupling unit for coupling the current and voltage signals having different frequency bandwidths into one signal and an analog-digital convert unit for converting an analog signal coupled as said one signal into a digital signal(s). And also, a power metering system including the same and a method for converting a signal of the power metering system are proposed.

Abstract: Disclosed herein are an apparatus and a method for removing a DC offset in a power meter. The apparatus for removing a DC offset in a power meter according to exemplary embodiment includes: an ADC; a HPF removing the DC offset from the signal output from the ADC; a selector receiving the signals passing through the HPF and bypassing the HPF and outputting any one thereof; a determination block receiving a signal output from the ADC or from the selector and determining whether the received signal is a sinusoidal signal; an offset calculation block calculating the DC offset to be compensated from the signal input to the determination block or output from the selector; and an offset compensation unit disposed on a path bypassing the HPF, compensating the calculated DC offset value in the signal output from the ADC and outputting the compensated result to the selector.

Abstract: A power measuring system, a measuring apparatus, a load terminal, and a device control system are provided. A voltage sensor detects a voltage waveform, and a current sensor acquires a current waveform, of a power line in a noncontact manner. A load terminal operates to connect the power line and a voltage measuring terminal to measure a current flowing from the power line to a load and to calculate a voltage value from the measured current value and the load. The load terminal transmits, in response to a request from a measuring apparatus, the measured current value and the calculated voltage value to the measuring apparatus via a communication means. A control portion of the measuring apparatus receives the current value and the voltage value from the load terminal. The control portion calculates a power value based on the received current value, voltage value voltage waveform and current waveform.

Abstract: Delivered power detection for power amplifiers (PAs) and related systems and methods are disclosed. The disclosed embodiments and techniques provide a delivered power indication for systems using PAs, including such systems for cellular telephone applications, allow power detection circuitry to be integrated on the same integrated circuit die as the PA, and provide power detection circuitry with output signals at baseband frequencies. In one embodiment, the delivered power detection circuitry includes output voltage level detection circuitry and output current level detection circuitry that provide current signals to multiplier circuitry, which in turn provides current output signals proportional to the actual delivered power to the load as represented by the incident power to the load reduced by the reflected power.

Abstract: A power consumption monitor, system, and method for monitoring power consumed by equipment, appliances, devices, buildings, and campuses is accomplished by passive sensors (12, 40) that detect power transmitted by individual conductors (C), and which include a current to voltage transformer with a passive, open-circuit electromagnetic force concentrator (22) positioned near the conductor (C). The sensor (22) generates an amplitude signal proportional to the power passing through the conductor (C). Programmable radios on a chip (32, 62, 72) and systems on a chip (34, 64, 74) are used to transmit the amplitude signal to a monitor (50) that displays the power being consumed along with actual and estimated cost and historical information. Software programs are implemented across the sensors (12, 40) and monitors (50) and a remote computer (80) to enable real-time monitoring power consumption with a resolution that spans from entire campuses down to single devices.

Abstract: An electricity consumption measurement apparatus, an electricity consumption measurement method, and a non-transitory tangible machine-readable medium thereof are provided. The electricity consumption measurement apparatus comprises a detector and a processor electrically connected to the detector. The detector is configured to detect an electricity consumption value and a voltage value. The processor is configured to calculate a variation rate according to the voltage value and a base voltage value. The processor adjusts the electricity consumption value according to the variation rate. The electricity consumption measurement method is able to perform the same operations as those performed by the electricity consumption measurement apparatus.

Abstract: A method of determining the utility consumption of each appliance in a collection of appliances by using periodic measurements of aggregate utility consumption of all appliances in the collection, is disclosed. The method comprises of determining the normal utility consumption of various modes of each appliance, fixing a measurement interval, and then measuring aggregate utility consumption at periodic intervals. In each interval, we first determine if the change in aggregate utility consumption in an interval is due to change in status (ON or OFF) of one of the appliances. Otherwise we determine if the change in aggregate consumption is due to a change in status of a pair of appliances. Otherwise, we determine if change in aggregate consumption is due to change in status of a triplet of appliances.

Abstract: The present invention provides a way to more effectively estimate energy usage by devices such as servers, including traditional mainframes as well as other enterprise systems. One core idea surrounds the fact that when detailed power consumption information is unavailable for a specific configuration, power consumption is computed/projected/estimated by de-rating the maximum power rating by a power adjustment factor that would more closely project the true power consumption. Under this approach, the power consumption is then provided as a range specifying probable expected lower and upper limits for a given device. This range is more meaningful for planning and decision-making and shows the client a more likely best and worst case energy consumption scenario for their specific device(s), and hence is helpful for planning or server comparison decisions. Cooling, energy costs, energy efficiency, and energy expanded per MIPS are also projected and given as a range instead of a single number.

Abstract: A device for sensing electrical current or voltage in an electrical distribution system using an actively compensated current ratio transformer that includes a first magnetic core having a first permeability and a second magnetic core having a second permeability higher than the first permeability. A primary winding having P turns is coupled with the first and second magnetic cores, a measurement winding having M turns is coupled with the first and second magnetic cores so that current in the primary winding induces current in the measurement winding, and a sense winding having S turns is coupled with the second magnetic core. An amplifier coupled to the sense winding receives a voltage developed across the sense winding and produces a compensation current in response to the received voltage. The amplifier has an output coupled to the sense winding to feed the compensation current through the sense winding to reduce the voltage developed across the sense winding voltage to substantially zero.