Abstract: Methods and systems for emulating high side current of a power switch including low and high side switches. The method includes generating, with a low side current sensor, a low side current signal for the low side switch when the power switch is in a low state. The method also includes generating, with a first transconductance amplifier, an emulated current signal based on an input voltage of the power switch. The method further includes generating, with a buffer, a fixed reference voltage by sampling the low side current signal when the power switch changes from the low state to a high state. The method also includes generating, with a capacitor, an emulated voltage based on the emulated current signal and the fixed reference voltage. The method further includes, generating, with a second transconductance amplifier, a high side current signal for the high side switch based on the emulated voltage.

Abstract: Systems and methods for calculating load direction even under adverse environmental conditions are provided. A system may include sensing circuitry and processing circuitry. The sensing circuitry may sense a first parameter and a second parameter of the electrical waveform on the transmission line of the electric power distribution system. The processing circuitry may determine a present load direction of an electrical waveform using a first method based at least in part on the first parameter in response to detecting that the sensing circuitry is experiencing a first environmental condition. The processing circuitry may determine the present load direction of the electrical waveform using a second method based at least in part on the second parameter and not the first parameter in response to detecting that the sensing circuitry is experiencing a second environmental condition.

Abstract: A power supply unit for an IED for LV or MV electric power applications characterized in that it comprises: a power transformer stage, which is operatively coupled to a feeding conductor to harvest electric power from said feeding conductor; a first storage stage, which is electrically connected to said power transformer stage to store electric energy; a first step-down conversion stage, which is electrically connectable/disconnectable to/from said first storage stage; a switching stage adapted to electrically connect/disconnect said first step-down conversion stage with/from said first storage stage; and a second storage stage, which is electrically connected to said first step-down conversion stage to store electric energy.

Abstract: A motor control apparatus applying a sinusoidal drive waveform to a motor and including a position detection unit outputting a signal according to a motor shaft's position; and a control unit: acquiring a phase value of the motor's drive waveform when a signal is output by the position detection unit, changing a cycle of the drive waveform by measuring time from a previously output signal to a presently output signal, comparing the phases of the drive waveform and the motor shaft, and controlling to change to a cycle at which a phase value of the drive waveform matches a target phase value when a travel time corresponding to a phase value for adjustment has elapsed from a present time when a phase value of the drive waveform presently acquired differs from a target phase value acquired when the motor's drive current and drive voltage are in a designated phase relationship.

Abstract: An impedance calibration circuit may be provided. The impedance calibration circuit may include an adjusting circuit. The adjusting circuit may be configured to generate a calibration code based on a variation voltage, which may be applied to a calibration node coupled to a calibration pad, and a reference voltage. The adjusting circuit may be configured to apply a voltage, which may be generated according to a control signal generated based on an operational voltage mode in accordance with the calibration code, to the calibration node. The adjusting circuit may include a plurality of leg circuits. At least one of the leg circuits may include a plurality of legs configured to be selectively coupled to the calibration node based on the control signal.

Abstract: An apparatus for AC physical signals measurement and data acquisition and the method for the same are provided. The apparatus for AC physical signals measurement and data acquisition comprises an analog sampling channel for inputting an AC signal and outputting an analog sampling value; a sampling switch for performing re-sampling to obtain data frequency as required by the receiving side; a register for storing a re-sampling value from the sampling switch; a bus for outputting the re-sampling value in the register to the receiving side; a timing controller for controlling the analog sampling channel and the re-sampling frequency of the sampling switch; and a digital low-pass filter, which has an input connected with the analog sampling value outputted by the analog sampling channel and an output connected with the sampling switch, filters out high frequency components from the sampling value, and has a cut-off frequency that should be lower than 0.5 times the re-sampling frequency of the sampling switch.

Abstract: A power monitoring system includes a plurality of current sensors suitable to sense respective changing electrical current within a respective conductor to a respective load and a conductor sensing a respective voltage potential provided to the respective load. A power monitors determines a type of circuit based upon a signal from at least one of the current sensors and a signal from the conductor, wherein the type of circuit includes at least one of a single phase circuit, a two phase circuit, and a three phase circuit. The power meter configures a set of registers corresponding to the determined type of circuit in a manner such that the configuring is different based upon each of the single phase circuit, two phase circuit, and three phase circuit suitable to provide data corresponding to the determined type of circuit.

Abstract: A control circuit 1 for determining a phase sequence of a power generator includes a frequency control unit, a cycle obtaining unit, a determination unit, and an output-supply control unit. The frequency control unit controls a frequency of a sensor signal synchronous with an operation of the power generator, and the cycle obtaining unit obtains a cycle of the sensor signal whose frequency is controlled by the frequency control unit. The determination unit determines the phase sequence of the power generator by detecting timing at which an output voltage outputted from each of the phases of the power generator has risen using the cycle of the sensor signal obtained by the cycle obtaining unit. The output-supply control unit controls a drive circuit according to the phase sequence of the power generator determined by the determination unit.

Abstract: A device includes an output circuit including a plurality of unit buffers, each of the unit buffers having an adjustable impedance; a controller circuit operable to selectively activate at least one of the unit buffers; and an impedance adjustment part operable to adjust the impedance of each of the unit buffers in response to a change of the number of the unit buffers that are selectively activated by the controller circuit.

Abstract: A power-supply noise measuring circuit includes a voltage fluctuation detecting circuit, a unit time generating circuit, a current measuring circuit, and a sampling circuit. The voltage fluctuation detecting circuit generates a detection current in accordance with a voltage fluctuation of a power supply. The unit time generating circuit generates a unit time in accordance with a clock signal. The current measuring circuit treasures an amount of the detection current per unit time. The sampling circuit samples the amount of the detection current measured by the current measuring circuit, every unit time. The present invention provides the power-supply noise measuring circuit that has a small circuit area and enough accuracy.

Abstract: This invention deals with an advanced Real-time Grid Monitoring System (RTGMS) suitable for both single-phase and three-phase electric power systems. This invention provides an essential signal processing block to be used as a part of complex systems either focused on supervising and diagnosing power systems or devoted to control power processors interacting with the grid. This invention is based on a new algorithm very suitable for real-time characterization of the grid variables under distorted and unbalanced grid conditions. The main characteristic of this invention is the usage of a frequency-locked loop, based on detecting the grid frequency, for synchronizing to the grid variables. It results in a very robust system response in relation to existing technique based on the phase-angle detection since grid frequency is much more stable variable than the grid voltage/current phase-angle, mainly during grid faults.

Abstract: A method of state estimation is provided, including: (a) acquiring a plurality of positive sequence voltage and current phasor measurements; (b) designating a reference positive sequence voltage phasor measurement from the acquired phasor measurements; (c) correcting the acquired phasor measurements to account for the reference phasor measurement; (d) calculating complex power having a real component and an imaginary component, using the corrected positive sequence voltage and current phasor measurement; (e) using the real component of said complex power as a calculated mega-watt and the imaginary component of the complex power as a calculated mega-volt-ampere; and (f) using the mega-watt and mega volt-ampere calculations in a state estimation algorithm.

Abstract: A meter device for checking the measurements of an electrical meter, such as that used by electrical utilities is provided. The meter device has a base with electrical phase conductors arranged to couple with a meter socket. A housing is attached to the base. Electrical connectors are arranged on the end of the phase conductors within the housing. The electrical connectors are arranged to couple with an electrical meter. One or more lead conductors is also provided. Each lead conductor has a first end coupled to the electrical connector and a second end coupled to the associated phase conductor. Each lead conductor includes a middle portion arranged outside of the housing.

Abstract: A meter device for checking the measurements of an electrical meter, such as that used by electrical utilities is provided. The meter device has a base with electrical phase conductors arranged to couple with a meter socket. A housing is attached to the base. Electrical connectors are arranged on the end of the phase conductors within the housing. The electrical connectors are arranged to couple with an electrical meter. One or more lead conductors is also provided. Each lead conductor has a first end coupled to the electrical connector and a second end coupled to the associated phase conductor. Each lead conductor includes a middle portion arranged outside of the housing.

Abstract: A method for measuring the impedance of electrical distribution equipment includes: applying a voltage at a first selected frequency to electrical distribution equipment, waiting a delay time for transient effects to settle, measuring current through the electrical distribution equipment, and selecting additional frequencies to repeat the steps of applying, waiting, and measuring.

Abstract: The present invention provides a digital automatic power interruption and re-supply relay for performing detection and comparing operation to inform a state of an accident with voice and numerals and automatically operating a connected relay to interrupt power when there occur abnormal changes such as interruption of electric power, open-phase, anomalous voltage, unbalanced voltage, negative-phase, overcurrent, and electric leakage in a power transmit and supply line of high and low voltage or special high voltage and high (low) voltage and, after compensating for the accident, for automatically re-supplying the power.

Abstract: Apparatus and methods for detecting the direction of a fault in relation to a switch connected between a source and a load are shown to include a voltage sampler for generating samples of the voltage during first and second power cycles. A current sampler generates samples of the current during first and second cycles. A first comparator compares the current samples from the first cycle to the current samples from the second cycle and determines the sign of the difference between the samples. A second comparator compares the sign of the voltage from the first cycle to the sign of the current difference determined by the first comparator and provides an indication of fault direction in relation to such comparison. The apparatus also includes a fault inception determiner, for providing a fault inception indication in relation to the voltage samples from the first and second cycles.

Abstract: A method and measuring device are provided for measuring the direction of rotation of a three-phase system. The measurement is carried out by measuring sensors. A coupling circuit is connected to each measuring sensor and transforms the voltage produced in the measuring sensor into rectangular pulses. The coupling circuit outputs are connected to a common logic device which determines the direction of rotation on the basis of the phase difference between the pulses.

Abstract: Disclosed is a watt/watthour meter which is capable of automatically correcting incorrect connections between the apparatus and a multiphase AC system. Each power line of the multiphase system is connected to the watt/watthour meter by means of a voltage input line and a current sensing coil. The apparatus is able to determine whether a given voltage input line is connected to the same power line as a given current sensing coil by determining whether the voltage applied to the given voltage input line has the same phase as the current running through the given current sensing coil. If the current and the voltage are the same, this information is stored, and the given voltage input line may be taken as being connected to the same power line as the given current sensing coil.

Abstract: A phase sequence indicator with two measuring contacts for contacting with connections of the object to be measured has a grouring contact touchable by the user, an evaluation circuit connected to the measuring contacts and the grounding contact, and an indicating device controlled by the evaluation circuit for indicating the direction of the rotary field. The evaluation circuit has a voltage-testing circuit for detecting the value of the voltage occurring between the measuring contacts, and the indicating device comprises additional indicating elements for indicating the value of the voltage.

Abstract: A method and a device for phase selection for single-pole tripping of high-impedance ground faults in direct grounded power networks. Starting from the ratio of the negative-sequence voltage to the zero-sequence current (U2/I0) and the ratio of the negative-sequence voltage to the positive-sequence voltage (U2/U1), two criteria with different conditions are formed, each of which indicating a faulted phase, and if both criteria indicate the same phase as faulted, single-pole tripping can take place.

Abstract: An adapter is provided for adapting a voltage or phase rotation indicator for use with multiphase electrical power. The adapter allows the phase rotation indicator to be used in situations where it might not otherwise be used, such as when the power conductors are not contained in a power meter box. The adapter may also be used as a protective carrying or transport cover for the indicator when the indicator is not in use.

Abstract: An electrical apparatus for visually indicating phase sequence, phase asymmetry and presence of three phases of an AC network comprising two transistors connected by their emitters to a first voltage terminal of the three phase network, the bases of the transistors being connected through diodes to a first voltage terminal and through crosscoupled phase shifting means to two other terminals of the three phase network. The collectors of the transistors are connected through resistors, light emitting diodes and diodes to two other voltage terminals and the emitters of the two transistors are connected through two other light emitting diodes to the first voltage terminal.

Abstract: A polyphase reversal detection and correction system which operates over a wide range of line frequencies and produces an automatic phase correction for maintaining proper phase sequence to a rotating device. The system includes a circuit arrangement for developing peak integrated signals by comparing the relation of various input phases, and developing an integrated reference phase signal. The input phase signals and the reference phase signals are compared to determine and correct the input phase sequence.

Abstract: A voltage rotation indicator for testing the phase sequence of live multi-phase electrical power is mounted within a housing. The housing is provided with structure for removably mounting the indicator on a meter box or can during voltage rotation testing. Contact plungers extend from the housing and contact meter jaw test points in the meter box during testing. Field personnel are thus not required to insert their hands into the meter box to attach test clips to the live circuit.

Abstract: This invention relates to a voltage sensor for sensing a voltage on an electrically charged object such as a distribution line or the like, the sensor being disposed with an insulation space to the object. The voltage sensor includes an amplifier circuit for outputting a signal having a waveform similar to that of a displacement current inflowing from the electrically charged object via the insulation space, and a filter circuit for extracting a signal having predetermined frequencies from the output of the amplifier circuit and outputting an alternating current waveform similar to the potential of the electrically charged object.

Abstract: This invention relates to a voltage sensor for sensing a voltage on an electrically charged object such as a distribution line or the like, the sensor being disposed with an insulation space to the object. The voltage sensor includes an amplifier circuit for outputting a signal having a waveform similar to that of a displacement current inflowing from the electrically charged object via the insulation space, and a filter circuit for extracting a signal having predetermined frequencies from the output of the amplifier circuit and outputting an alternating current waveform similar to the potential of the electrically charged object.

Abstract: A negative sequence occurring in a polyphase power system control including a continuous wave frequency transducer causes a second harmonic to be generated which for a 60 Hz system comprises a 120 Hz signal. In a preferred embodiment of the invention, the continuous wave frequency transducer includes an active 120 Hz notch filter having one stage which provides a component of the 120 Hz second harmonic. This signal is coupled to a second harmonic detector implemented by a semiconductor diode connected to the output of an operational amplifier. The detector diode is coupled to one input of a comparator circuit whose other input is coupled to a selectable DC reference signal. The comparator operates to generate a fault indicating signal indicative of a negative sequence when the output from the second harmonic detector exceeds the reference.

Abstract: A protective relay for detecting power arcing faults on a three-phase electrical power spot network. A phase-to-phase power arc on a spot network produces harmonics on the phase-to-phase voltages, and the phase currents; a phase-to-ground arc produces harmonics on the phase-to-neutral voltages. The protective relay of the present invention monitors one or more of the three phase-to-phase voltages, the three phase-to-neutral voltages, or the three phase currents and indicates a fault based on the harmonic content of those signals.

Abstract: Disclosed is a phase sequence network. The network is compensated for frequency variations in the signal applied to the sequence network so as to develop a desired sequence component output that is accurate over a limited but adequate range of frequencies.

Abstract: Negative sequence filters employing one to three operational amplifiers and a single reactive element generate the negative sequence voltage of a three phase AC power system by generating two line-to-line voltages, phase shifting one of them to bring them into phase and summing the resultant signals. The phase shifting circuit includes a potentiometer, one end of which serves as the input to the circuit and the other end of which is connected to the inverting input of an operational amplifier. A capacitor is connected between the tap point of the potentiometer and ground and the values of the components are selected so that the tap point of the potentiometer can be positioned to compensate for variations in the capacitive reactance of the capacitor without affecting the magnitude of the phase shifted signal.

Abstract: Sequence network circuits are provided for use in three-phase protective relaying applications. In one embodiment, the circuit includes input circuit means for receiving input signals, one of which comprises a reference input signal, and signal processing means for processing such input signals. The signal processing means includes an operational amplifier and a single capacitor. A plurality of resistors couple the input signals to the operational amplifier. The value of the resistors and the capacitor are selected such that the output signal of the operational amplifier is representative of the quadrature voltage, relative to the reference input signal, and shifted 90.degree. lagging with respect to its normal phase position. Other embodiments are disclosed.

Abstract: A three-phase electrical transformer utilizes a conductor independent of the transformer windings for sensing zero sequence current upon the occurrence of a ground fault. A current transformer coupled with the independent conductor provides polarization to protective relay devices. One embodiment utilizes the transformer internal tank shield in combination with the current transformer for providing zero sequence current.

Abstract: A method and apparatus are disclosed for accurately determining negative sequence current in a three-phase turbine-driven generator, the currents indicative of power oscillations and of torques harmful to turbine buckets. A signal conditioner and phase-shifter network are described which provide precise amplitude and phase angle adjustments and null balancing features which permit accurate determination of the magnitude of negative sequence current even though this current is a very small quantity determined as the difference between two large signals.

Abstract: The circuitry for generating filter excitation signals from a multi-phase alternating current input is provided with the following circuitry for each phase of the multi-phase alternating current input. A current transformer connected to a respective phase of the multiphase alternating current input is connected to a bridge rectifier having one node connected to a neutral conductor and including a resistor of equal resistance value connected in each parallel branch of the bridge rectifier between the neutral conductor and the input of the current transformer. An operational amplifier having inputs respectively responsive to the voltage across each of the respective resistors in the bridge rectifier generates an output for one phase of the excitation signal to the filter. The filter excitation circuitry has application to two-phase and three-phase systems wherein the excitation circuitry is identical for each phase.

Abstract: A symmetrical component sequence filter which provides a signal responsive to a predetermined sequence quantity of an electrical power system, while using only one phase shift other than 180 degrees. A single reactive element provides the phase shift. A single adjustable resistor calibrates the filter when the reactive element is non-precision. Selecting a precision reactive element eliminates even the single adjustment. The symmetrical component sequence filter enables both a positive and a negative sequence component to be simultaneously derived from common processing circuitry, requiring only one additional reactive element.

Abstract: A local power source, such as a battery, is connected to a tone generator oscillator circuit which includes an audio reproducer. The tone generator includes a voltage sensing element such as a dark-resistance photoconductor, a resistor, or a Zener diode, at which the voltage is sensed when connected in a phase sequence circuit network or other network to be tested. The output tone, whether present or not, is indicative of a predetermined phase sequence of connection of test terminals. A transfer switch can connect the oscillator directly or through dropping resistors or non-linear resistances such as a Zener diode to the test terimals so that the test terminals can also be used to test for external resistance, short circuits, or polarity of applied voltages in the network which, depending on their polarity, may introduce external voltages, thus modifying the tone of oscillation of the tone generator.

Abstract: A voltage rotation indicator for testing the phase sequence of live multi-phase electrical power is mounted within a housing. The housing is provided with structure for removably mounting the indicator on a meter box or can during voltage rotation testing. Contact plungers extend from the housing and contact meter jaw test points in the meter box during testing. Field personnel are thus not required to insert their hands into the meter box to attach test clips to the live circuit.