Abstract: A method for identifying a fault condition associated with a power line conductor of an electrical power distribution network. The method determines if a load current carried by the conductor is above a minimum load current, determines a learned phase angle relationship between the load current and a source signal, determines a load current magnitude, determines a real-time phase angle relationship between the load current and the source signal and indicates a fault condition when the real-time phase angle relationship is within a predetermined number of angular degrees of the learned phase angle relationship and when the load current magnitude exceeds a fault-indicating current.

Abstract: The invention concerns a method and computer program product for determining the direction of fault in an electrical power system as well as to a fault handling device. In the fault handling device the voltage at a measurement node of the power system is measured, the phase (?PF) of this voltage (VPF) before a fault is stored, the phase (?F) of this voltage (VF) at the end of a time interval (TI) following directly after a detected fault is determined, a phase offset (?O) is determined as the difference between the phase (?PF) of the measured voltage (VPF) before the fault and the phase (?F) of the measured voltage (VF) at the end of the time interval (TI) and the phase (?F) of the measured voltage (VF) after the detection of the fault is adjusted with the phase offset (?O). Thereafter the adjusted measured voltage is used in determining the direction of fault in relation to the measurement node.

Abstract: An apparatus and method is provided for identifying a faulted phase in at least one shunt capacitor bank. The apparatus generally includes a sampling circuit for sampling current or voltage signals associated with the shunt capacitor bank. A microcontroller is coupled to the sampling circuit and programmed to measure a compensated neutral point phase angle from the sampled signal, and compare the compensated neutral point phase angle with a fixed reference phase angle to identify the faulted phase of the shunt capacitor bank. The method generally includes the steps of sampling a current or voltage signal associated with the shunt capacitor bank, determining a compensated neutral point phase angle from the sampled signal, and comparing the compensated neutral point phase angle with a fixed reference phase angle to identify the faulted phase of the shunt capacitor bank. The invention also relates to an apparatus and method for identifying the location of the fault (e.g.

Abstract: A circuit for testing phase detectors in a delay locked loop is provided. The circuit uses a second phase detector arranged to receive the signals entering a first phase detector. Particularly, the circuit is routed such that a signal entering the D input of the first phase detector is inputted into the clock input of the second phase detector, and a signal entering the clock input of the first phase detector is inputted into the D input of the second phase detector. The circuit is also coupled to a test controller located on-die or at a high volume manufacturing (HVM) tester.

Abstract: A method for determining an adjustment value for an electrical protection device wherein, upon occurrence of a ground short circuit, first current indicator measured values and first voltage indicator measured values are captured by a first measurement device at a first end of a segment of an electrical power supply line, and second current indicator measured values and second voltage indicator measured values are captured by a second measurement device at a second end of the segment of an electrical power supply line. In order to design a method of this type such that an adjustment value for a ground impedance can be determined in a relatively simple fashion.

Abstract: A method for locating a fault in a two-terminal power transmission or distribution line. Measurements of the three phase currents are received from both terminals. Measurements of the three phase voltages are received from one line terminal. Parameters of the line are received. The fault type is received. Based on this received information the distance to fault from the one terminal where the phase voltages were measured is determined and output. Since only the phase voltages of one line terminal are needed, the functionality of a device, in particular a current differential relay, can be expanded to determine the distance to fault in an off-line mode.

Abstract: A method for fault detection in a power transformer/autotransformer and/or interconnected power lines, which are within the zone protected by the differential protection, and particularly suitable for detecting turn-to-turn faults in power transformer/autotransformer windings. All individual instantaneous phase currents of the protected object are measured, individual phase currents as fundamental frequency phasors are calculated, the contributions of the individual protected object sides negative sequence currents to the total negative sequence differential current are calculated by compensating for the phase shift of an eventual power transformer within the protected zone, the relative positions of the compensated individual sides negative sequence currents in the complex plane are compared, in order to determine whether the source of the negative sequence currents, i.e.

Abstract: A control system for an electrical power system includes an electrical corrective device, a voltage measuring device coupled to each phase of the electric power system, a current measuring device connected between each phase of the electric power system and the electrical corrective device, and a protective device connected to outputs of the voltage measuring device and the current measuring device. The protective device includes a controller configured to detect an imbalance using the measured voltages and currents output from the voltage measuring device and the current measuring device without using or independently of other recent voltage or current measurements for other points in the electrical corrective device and independently of a neutral-ground measurement at the electrical corrective device.

Abstract: An appliance and a method are intended to monitor a phase line of a section of an electrical energy grid line. The appliance comprises a device for monitoring a parameter of a phase line. The parameter is representative of routine operating conditions of the phase line and has a known propagation speed. The appliance also comprises a device for generating an event detection signal each time the parameter has a value that exceeds a threshold, and for storing a reception time when the detection signal is generated. The appliance also has a device for sending a signal representative of a geographic location of the end of the section and a device for performing a geographic location of the event once two consecutive detection signals are generated from the signal representative of the geographic location, and reception times associated with the two detection signals.

Abstract: A system and a method for determining a position of a single phase fault to ground in a feeder line are provided. The feeder line is electrically connected to an electrical substation via a substation bus. The system includes first and second sensors electrically coupled to a transformer in the electrical substation. The system further includes a processor that determines a reactance value based on measured electrical characteristics and a predetermined constant. The processor accesses a table having a plurality of position identifiers associated with positions on the feeder line, and a plurality of reactance component values corresponding to positions on the feeder line relative to the substation bus. The processor selects a first reactance component value from the plurality of reactance component values in the table to determine the position of a fault.

Abstract: The present invention provides for disambiguating the phase of a field received from a wireless tracker in an electromagnetic (“EM”) tracking system. In a first method, a carrier wave signal is modulated with a tracking signal transmitted by an EM tracker. A time reference indicating a starting point for a particular phase of the carrier wave signal is determined and is used to determine the proper phase for the tracking signal. In a second method, the EM tracker transmits auxiliary data that includes the proper phase of the tracking signal. In a third method, the EM tracker includes a passive transponder that receives a desired phase of a tracking signal as auxiliary data in an excitation signal. In response, the EM tracker transmits the tracking signal according to the desired phase. Tracking electronics may then lock onto the proper or desired phase determined according to any of the disclosed methods.

Abstract: A system and a method for determining a position of a single phase fault to ground in a feeder line are provided. The feeder line is electrically connected to an electrical substation via a substation bus. The system includes first and second sensors electrically coupled to a transformer in the electrical substation. The first sensor measures an amplitude and a phase angle of an electrical current being output by the transformer to the substation bus electrically connected to the feeder line. The second sensor measures an amplitude and a phase angle of a voltage being output by the transformer to the substation bus electrically connected to the feeder line. The system further includes a processor that determines a reactance value based on the amplitude of the electrical current, the amplitude of the voltage, a phase angle between the electrical current and the voltage, and a predetermined constant.

Abstract: A method and apparatus is disclosed for determining the incident energy of a system. Specifically, there is provided a technique comprising measuring a voltage of an ac waveform, causing a resonant ring in the ac waveform, measuring a frequency of the resonant ring, computing a line impedance based upon the measured voltage and the frequency of the resonant ring, and computing a bolted fault current based on the line impedance and the measured voltage.

Abstract: In order to make accurate predictions on whether or not a power grid is stable, it is desirable to know the frequency and phase of at least each “control area” in the power grid. Each control area will ideally have power generation matched with its load. Rather than measure thousands of data points at low resolution in order to calculate potential grid instabilities, one may make few highly accurate measurements at low voltage to predict frequency and phase of high voltage transmission lines. Predicted data at the transmission points can then be used to calculate the relative stability of the power grid. The method includes the use of non-linear Luenberger observers and Kalman filters. The method can also be used to compute “Virtual measurements” for any component in the connected grid based on lower cost or easier to obtain measurement at other points on network. This method applies to any connected network of components.

Abstract: A method for identifying a fault condition associated with a power line conductor of an electrical power distribution network. The method comprises determining a load current carried by the conductor is above a minimum load current, determining a learned phase angle relationship between the load current and a source signal, determining a load current magnitude, determining a real-time phase angle relationship between the load current and the source signal and indicating a fault condition when the real-time phase angle relationship is within a predetermined number of angular degrees of the learned phase angle relationship and when the load current magnitude exceeds a fault-indicating current.

Abstract: Power supplies are disclosed herein. One embodiment of a power supply comprises a first input and a second input, wherein the first input and the second input are connectable to a pulse width modulation controller and wherein a pulse width modulation signal is outputable from the pulse width modulation controller. A power stage connected to the first input and the second input. A first comparator having a first comparator first input is connected to the first input and a first comparator second input connected to the output of the power stage. A change of voltage at the output of the first comparator constitutes a difference in phase between the first input and the output of the power stage.

Abstract: A system and method for locating faults on multi-terminal power system transmission lines uses synchronized phasor measurements to accurately determine fault location and fault impedance regardless of fault type, fault resistance, and coupling to other adjacent power system transmission lines.

Abstract: A DC motor phase detection algorithm that monitors the change in motor current to detect pulses in the current caused by the motor's commutator brushes crossing over the gap between rotor commutator segments as the motor shaft rotates. A pulse is generated each time a commutator brush breaks and then reconnects to a commutator segment. The algorithm detects and counts the pulses in order to determine the number of revolutions the shaft has rotated. The motor phase can then be used to determine the distance, rotational or linear, that the moving portion of the load attached to the motor has traveled. If the initial position of the moving portion of the device is known then the absolute position can be calculated.

Abstract: Provided is an apparatus and method for determining a faulted phase resulting from a fault in a three-phase ungrounded power system. The method includes comparing a phase angle of an operating phasor to a phase angle of a fixed reference phasor. The operating phasor is derived from a digitized signal sample of a plurality of measured signals of the power system. The method also includes comparing a phase angle difference between the operating phasor and the fixed reference phasor to at least one threshold to determine the faulted phase. The fixed reference phasor may be a phase-to-phase voltage or a positive sequence voltage of the plurality of measured signals of the power system. The operating phasor may be a zero sequence current, a zero sequence voltage or a combination of a zero sequence current and a zero sequence voltage of the plurality of measured signals of the power system.

Abstract: When supplying electric power to a superconducting cable including a superconducting shield covering a superconductive conductor, a phase A of a current generated by a magnetic field leaking from the superconducting shield and a phase B of a current passing through the superconductive conductor are detected, and a phase difference between the phase A and the phase B is obtained so as to determine that a quench has occurred in the case where a difference between a reference phase difference and the obtained current phase difference exceeds a threshold.

Abstract: The present invention is directed to a method and apparatus for improving operational reliability during a loss of a phase voltage (LOV) in a multi-phase power system, wherein a voltage representative of the LOV phase is calculated. The representative voltage is used for computing a reference polarizing voltage suitable for a protection unit.

Abstract: A method to locate a fault from one end of a section of a power line utilizing measurements of current, voltage and angles between the phases at a first end of said section. Symmetrical components of currents are calculated for the current and voltage measurement at the first end. A value of impedance is calculated for an extra link between the terminals with the impedance for the positive sequence. A compensation is determined for the shunt capacitance. The zero-sequence current is determined from the healthy line of a section of parallel power lines. A distance to a fault is calculated for the parallel line section. The distance to the fault from the first end is calculated. The fault is located utilizing the calculate distances.

Abstract: A polyphase power system with a system safety ground supplies a plurality of power phases over a respective plurality of power lines to power a load. A plurality of phase fault detectors of a fault detection component monitor the plurality of power lines, respectively. A phase fault detector, of the plurality of phase fault detectors, monitors a power line of the plurality of power lines. The phase fault detector outputs a threshold voltage with a voltage divider coupled with the power line. The threshold voltage is a line-to-ground voltage relative to a localized ground. A capacitor coupled between the localized ground and the system safety ground provides a direct current offset to the localized ground upon a ground fault condition. The phase fault detector compares the threshold voltage with a reference voltage to make a determination of an existence of the ground fault condition in the power line.

Abstract: The present invention relates to a method to locate a fault in a section of a transmission line using measurements of current, voltage and angles between the phases at a first (A) and a second (B) end of said section. The invention is characterised by the steps of, after the occurrence of a fault along the section, calculating a distance (dA, dB) to a fault dependent on a fault current measured at one of said first and second ends and phase voltages measured at both of said first and second ends (A, B), where the distance to fault is calculated from the end (A or B) where the fault current is measured. The invention is particularly suitable when a current transformer at either of the first or second ends (A, B) is saturated. If so, then, a distance (d) to a fault is calculated dependent on a fault current measured at the non-affected end and phase voltages measured at both the affected end and the non-affected end.

Abstract: A method and a device is provided for controlling a switching converter comprising a high side switch and a low side switch. The method comprises testing the high side switch for a short circuit, and upon detection of a short circuit in the high side switch, leaving the switching converter in an operationally reliable state or shifting the converter to an operationally reliable state.

Abstract: A method of measuring phase includes receiving an analog signal; converting the analog signal into a digital signal; representing the digital signal as N sets of samples; aligning the N sets of samples to a common time frame; removing zero bias drift from the digital signal; and calculating a phase of the analog signal based on the digital signal with the zero bias drift removed. The phase can have a time resolution substantially equal to a time between adjacent samples.

Abstract: A substrate inspection apparatus includes a first waveform measurer which acquires a first amplitude waveform that is the amplitude waveform of an AC voltage obtained from a semiconductor of a semiconductor substrate which is being inspected when an external AC power source is connected to the semiconductor and an AC voltage from the AC power source is applied to the semiconductor, the semiconductor substrate also having an interconnection that is supposed to be connected to the semiconductor; a second waveform measurer which is connectable to the interconnection of the semiconductor substrate and acquires a second amplitude waveform that is the amplitude waveform of a voltage in the interconnection when the AC voltage is applied to the semiconductor; and an evaluator which calculates the phase difference between the first amplitude waveform and the second amplitude waveform and extracts information on a defect of the semiconductor substrate on the basis of the thus-calculated phase difference.

Abstract: The invention relates to a device and a method for monitoring the connection of an electrical supply unit comprising voltage detection (32) detecting phase voltage (14), current detection (32) detecting phase voltages (38), a transformation unit (66) transforming the phase voltages (38) after conducting field-oriented regulation in at least one cross current (62), wherein a monitoring device (34) is provided to monitor at least one supply connection (28, 36) by means of which an electrical supply unit (32) is supplied, said monitoring unit evaluating the variation of the cross current (62) in order to monitor the connection.

Abstract: A method for quantifying effects of resonance in an integrated circuit's power distribution network is provided. The power distribution network includes a first power supply line and a second power supply line to provide power to the integrated circuit. Test ranges are selected for two test parameters, reference voltage potential of a receiver and data transmission frequency of the integrated circuit. At each combination of the two test parameters, bit patterns are transmitted by the integrated circuit to the receiver. A comparison is made between the transmitted bits and the received bits to determine whether the transmitted bits were correctly received. The comparison may be used to determine and report a range of values for the reference voltage potential and data transmission frequency that allow the transmitted bits to be correctly received.

Abstract: Apparatus and methods for detecting high level arc faults in aircraft power systems are disclosed. One embodiment of the invention with reduced susceptibility to nuisance trips includes three low pass filters each having an output connected to a threshold detector. In addition, a three input comparator is connected to an output of each of the threshold detectors and a fault verification circuit is connected to an output of the three input comparator. An embodiment of the method of the invention for detecting arc faults in three phase aircraft power systems involves detecting at least one of the three phases having a current exceeding a predetermined threshold, detecting differences between the three phases and generating a signal indicative of difference being detected between the three phases for a time period exceeding a predetermined duration.

Abstract: A wood drying installation for a wood drying kiln including a pair of electrodes adapted to be inserted into a wood stack contained in the kiln, a resistance connected in a series circuit with the electrodes, an AC voltage source connected to apply an AC voltage across the series circuit, a phase detecting circuit connected to the series circuit operable to generate a signal representing the phase angle between AC voltages applied to different parts of the series circuit, and a processor to receive the signal. The system is operable to determine a moisture value corresponding to a capacitive component of the reactive impedance between the electrodes in accordance with a predetermined arithmetic algorithm relating the value to the phase angle.

Abstract: A method, computer program, and system for real-time signal analysis providing characterization of temporally-evolving densities and distributions of signal features of arbitrary-type signals in a moving time window by tracking output of order statistic filters (also known as percentile, quantile, or rank-order filters). Given a raw input signal of arbitrary type, origin, or scale, the present invention enables automated quantification and detection of changes in the distribution of any set of quantifiable features of that signal as they occur in time. Furthermore, the present invention's ability to rapidly and accurately detect changes in certain features of an input signal can also enable prediction in cases where the detected changes associated with an increased likelihood of future signal changes.

Abstract: A gate comparator control panel, in accordance with the subject invention, allows a user to define up to four different gate regions that may exist on any of the live waveforms, maths waveforms, or REF waveforms. A menu for each gate controls the position of each gate and selects the source for the signal that is to be gated. All gates must be the same width. A high level application copies the gated region of a waveform into a REF memory. For example, Gate 1 would go into REF 1, gate 2 into REF2 and so on. A user-settable tolerance value is used to determine if difference between the waveforms of the gates reaches a point at which a violation is indicated. A master gate position control causes all gates to move by the same amount, thus maintaining a constant distance between them. A master gate width control causes all gates to change width.

Abstract: A system and method for fault detection including a transmitter adapted to transmit a composite signal on a buried cable so that fault leakage of the composite signal returns to the transmitter through the ground surrounding the buried cable. The composite signal is composed of a low frequency first component that alternates at a first frequency and that defines a phase, and a low frequency second component that alternates at a second frequency higher than the first frequency and that defines a duty cycle having a predetermined relationship with the phase of the first component. A receiver receives the composite signal from the probe and filters the first component, filters the second component, defines an alternating reference signal having a phase based on the duty cycle of the filtered second component, and compares the phase of the reference signal with the phase of the filtered first component.

Abstract: A method and apparatus for measuring quantities of a multi-phase electric line, the apparatus comprising a control unit and a measurement unit in connection with each phase conductor of the electric line, wherein each measurement unit is arranged to measure a first phase quantity of the phase conductor in connection with which it is located and to transfer the measured quantity value to the control unit, the measurement unit located in connection with one phase conductor being further arranged to measure phase angles between the first phase quantity of said phase conductor and first phase quantities of other phase conductors and to transfer the measured phase angle values to the control unit.

Abstract: The apparatus detects an out-of-step condition following the clearing of an external multi-phase fault in a protective relay. The apparatus includes a circuit which detects the presence of an external multi-phase fault on the power line and a timing circuit for readying an out-of-step logic detection circuit in the protective relay if the external fault remains for a pre-selected period of time. An out-of-step condition is declared and a signal blocking operation of selected distance elements in the protective relay is produced if the positive sequence impedance on the line remains inside an outer protection zone boundary in the impedance plane for a selected period of time, wherein the out-of-step blocking signal continues as long as the positive sequence impedance remains inside the second boundary.

Abstract: The present invention relates to a method, an apparatus and a computer program for inspecting laminated iron cores (1) of electrical machines for interlamination shorts, in which the laminated iron core (1) is magnetized by means of an auxiliary winding, and the iron surface is scanned by means of at least one measurement coil arrangement (2) with a downstream measurement device. In this case, unique and quantifiable localization of interlamination shorts is achieved by using both the phase (8) and the amplitude (7) of the electrical signal which is induced in the at least one measurement coil arrangement (2), in combined form.

Abstract: The operating mode of a power modulation system is determined according to the nature of the load. The power modulation system can operate in either of two operating modes, namely a “reverse phase control” mode and a “forward phase control” mode. To this end, the load is supplied with power under predetermined low-load operating conditions by the power stage in the “reverse phase control” mode, overvoltages are detected and the power modulation system is caused to change to the “forward phase control” operating mode if an excessive number of overvoltages is detected.

Abstract: A process and an apparatus for measuring the impedance of a capacitive sample and thereby determining the leakage impedance and the loss angle. To suppress the effects of ambient power frequency fields coupling onto the test object, measuring frequencies on either side of the line frequency are imposed onto the test object. The voltage and current are captured using a detection system. These signals are digitised and processed using a computer to determine the real and imaginary voltages and currents at the two test frequencies. These components are then analysed to calculate the leakage impedance and phase angle at the two frequencies. By applying a linear interpolation between the two points, the impedance and loss angle at the line frequency can be measured.

Abstract: A method of measuring the PLL lock time includes deriving the PLL frequency-settling function by demodulation and envelope extraction in the time domain. The PLL lock time can then be calculated from this function. Using this PLL lock time measurement method provides for very good frequency and time accuracy. Also, since for demodulation, the settled signal is used for multiplication, ATE synchronization is not required. Furthermore, since all the processing is done in the time domain, calculation times are reduced, making the process suitable for ATE environments.

Abstract: A method and system for determining and compensating for phase and time errors in an optical receiver. The method and system includes use of a measurement and reference signal; deriving phase and time errors; and providing compensation values to the optical receiver. The operating frequency and/or other operating parameters associated with phase and time errors are determined and recorded to allow for proper compensation to the optical receiver.

Abstract: A method for generating a fault signal in a system voltage regulator by a phase signal includes detecting the system voltage and phase signal; comparing the system voltage and phase signal with respective fault levels; and generating a fault signal upon either the system voltage or the phase signal falling below the respective fault level of the fault levels. The fault signal generating method also inhibits generating a fault signal using a drive signal of the system voltage regulator. A diagnostic circuit for a system voltage regulator is also disclosed.

Abstract: An injection test signal generator is incorporated into a circuit breaker. In this way, injection testing can be performed by causing the internal test signal generator to generate test signals and feed those signals to the trip circuitry of the circuit breaker. No independent injection test signal generator need be purchased or stored, or transported to the location of the circuit breaker and hardwired thereto. Various methods of communicating with the internal test signal generator can be implemented, including, for example, a standard interface, a wireless interface or a network interface. Dences can also be provided to selectively isolate the internal test signal generator from the trip circuitry to prevent accidental and erroneous breaker trips.

Abstract: Disconnection device for an electronic operating device for gas discharge lamps. The filament breakage of a lamp is evaluated by detecting the current through a component which flows through the filaments. This is performed either by detecting this current with the aid of an optocoupler or by measuring the phase of the load circuit current.

Abstract: The present invention relates to a method for detecting a line-to-ground fault location in power network, and more particularly, detecting the line-to-ground fault location by direct 3-phase circuit analysis without using a symmetrical component transformation, so even in an unbalanced 3-phase circuit, the line-to-ground fault location can be accurately detected. In the method using direct 3-phase circuit analysis of this invention, inverse lemma is used to simplify matrix inversion calculations, thus the line-to-ground fault location can be easily and accurately determined even in the case of an unbalanced network without symmetrical component transformation.

Abstract: The inventive method assesses the stability of an electric power transmission network, where said network comprises a plurality of substations, buses and lines, and a system protection center (8). It comprises the steps of 1. measuring phasor data (9) for voltages and currents at a plurality of locations of the network, 2. transmitting said phasor data (9) to said system protection center (8), 3. transmitting information (5) regarding the state of switches of at least one substation to the system protection center (8), and 4. the system protection center (8) determining at least one stability margin value of the transmission network. In this way, detailed real-time information about the state of the network is collected at a system level of the network, allowing a corresponding global analysis of the information. In a preferred embodiment of the invention, the system protection center determines one or more control commands (6), based on the phasor data (9) and on the state of switches.

Abstract: A three-phase motor protector uses two toroids to monitor all three phases of a three-phase motor. Current and phase loss are monitored directly in phases A and B while the phase C current level is determined by analysis of the phase A and B relationship. Current is induced into the phase A and B toroids from the motor supply lines with the resulting wave fed to an input of high-gain inverting amplifiers to provide A and B square waves which are inputted to separate channels of a microprocessor (U3). The square waves are processed by an AND gate providing an output square wave with a 16.66 percent duty cycle for normal operation. Upon loss of phase C the ANDed result is a digital low since the individual waves of phases A and B become an inverse of one another. In order to prevent nuisance tripping an AND output of less than 2 percent duty cycle is treated as a phase loss.

Abstract: A fault detection apparatus for use in an electrical distribution network to distinguish normal network operations from various network faults. Pre-event and post-vent signal patterns are compared and analyzed to produce an event characteristic which distinguishes the faulted feeder and the faulted phase. The characteristic also allows for discrimination between the various events and controls network response accordingly.

Abstract: A wood drying installation for a wood drying kiln including a pair of electrodes adapted to be inserted into a wood stack contained in the kiln, a resistance connected in a series circuit with the electrodes, an AC voltage source connected to apply an AC voltage across the series circuit, a phase detecting circuit connected to the series circuit operable to generate a signal representing the phase angle between AC voltages applied to different parts of the series circuit, and a processor to receive the signal. The system is operable to determine a moisture value corresponding to a capacitive component of the reactive impedance between the electrodes in accordance with a predetermined arithmetic algorithm relating the value to the phase angle.

Abstract: A method for generating a fault signal in a system voltage regulator by a phase signal includes detecting the system voltage and phase signal; comparing the system voltage and phase signal with respective fault levels; and generating a fault signal upon either the system voltage or the phase signal falling below the respective fault level of the fault levels. The fault signal generating method also inhibits generating a fault signal using a drive signal of the system voltage regulator. A diagnostic circuit for a system voltage regulator is also disclosed.