Abstract: Method and apparatus for detecting a ground fault, the apparatus including diagnostics unit arranged to monitor a sum current of output phases of a frequency converter, diagnostics unit arranged to detect a ground fault, if the sum current exceeds a predetermined threshold value, and diagnostics unit for performing the initial setting of the threshold value, the diagnostic unit being arranged to determine the value of the sum current when the frequency converter starts up and to set the threshold value so that it is greater than the predetermined value of the sum current.

Abstract: Disclosed are abnormality detecting apparatus and method for a high-voltage circuit (A), in which: a square wave pulse is outputted to a measuring point (p1) with a switch (SW1) set off, the switch (SW1) provided between an inverter circuit (2) and the ground, a difference voltage (Vp-p) between a voltage (Vh) detected at a phase of T/2 and a voltage (V1) detected at a phase of T is obtained, the occurrence of a ground fault is detected based on the size of the difference voltage (Vp-p); and the square wave pulse is outputted to the measuring point (p1) with the switch (SW1) set on, and it is judged that a loosening of a fastening section (p2) occurs when the difference voltage (Vp-p) exceeds a reference voltage (Vref2).

Abstract: Methods and apparatus provide for: measuring leakage current from a source of AC power, which provides power to at least one load circuit; and comparing the measured leakage current values against one or more predetermined thresholds to establish status therefor; and automatically performing self tests to determine whether the leakage current sensing and comparing operations are operative.

Abstract: An insulation state detector includes a capacitor, a measurement section measuring a charging voltage of the capacitor, a measuring circuit that connects the capacitor, which is insulated from a DC power source after being charged by the DC power source, between the measurement section and a ground potential portion, a detector detecting an insulation state of a voltage boosting circuit, and a reversed-polarity measuring circuit that connects the capacitor to the measurement section and the ground potential portion with reversed polarity when a potential corresponding to a division ratio of a positive-side ground fault resistor and a negative-side ground fault resistor on a secondary side of the voltage boosting circuit exceeds a positive potential of the DC power source and the capacitor is charged with reversed polarity by a secondary-side positive potential at the time of charging of the capacitor using the positive potential of the DC power source.

Abstract: An electronic trip device is described that includes a test signal generator coupled to at least one of a line conductor and a neutral conductor and configured to create a test signal. The electronic trip device also includes a leakage current detection circuit configured to compare a current in the line conductor and a current in the neutral conductor, the leakage current detection circuit configured to output an error signal if the test signal is not detected.

Abstract: The present invention relates to a ground fault detecting and controlling method for a parallel-structured high voltage system, and more particularly, such a ground fault detecting and controlling method for a parallel-structured high voltage system, in which it can be more precisely determined whether or not the system operation is emergently stopped based on individual insulation resistance values for respective items of the system, and it can be determined whether there is the possibility of temporary operation of the system in the emergency stop situation of the system operation. According to the present invention, a combined insulation resistance ground fault reference value is calculated based on individual insulation resistance values for respective items of the system, and the entire system is controlled by using the calculated combined insulation resistance ground fault reference value such that a high-accuracy ground fault detecting and controlling method can be provided.

Abstract: A fault detection system is provided for a power distribution system having at least first and second line conductors carrying AC currents that are out of phase with each other from a source to a load, and a common neutral conductor. The system includes an arcing fault current sensor comprising a coil wound on a hollow core and coupled to both of the line conductors in a manner that the electrical currents in the line conductors flow in opposite directions inside the hollow core, thus inducing in the coil an output signal that is a function of the difference of the electrical currents in the line conductors. A neutral current sensor produces an output signal representing the magnitude and phase direction of current in the neutral conductor.

Abstract: Testing an AFCI device includes providing an AFCI device to be tested and a load, wherein the AFCI device and the load form an electrical circuit, applying AC power to the AFCI device, generating a high frequency broadband noise signal, amplifying the high frequency broadband noise signal, modulating the amplified high frequency noise signal with a signal synchronized to the load current or load voltage to provide synchronized high frequency broadband noise bursts, coupling the noise bursts into the electrical circuit to simulate series arcing signals, determining if the AFCI device opens the electrical circuit within a predetermined amount of time, indicating the AFCI device has passed the test if the AFCI opens the electrical circuit within the predetermined amount of time, and indicating the AFCI device has failed the test if not.

Abstract: A motor drive system provides for analysis of current flow in the DC bus to identify ground faults and their locations. Low-frequency positive polarity and negative polarity current differences indicate ground faults from the positive DC bus and negative DC bus respectively. High-frequency signals indicate ground faults in the motor windings and connecting leads.

Abstract: The present invention is implemented by deploying an enhanced ground fault detection and location apparatus and by using the apparatus in conjunction with specific circuit analysis methods, using the information generated by the ground fault detection and location apparatus. The ground fault detection and location apparatus comprises the functionality of a voltmeter, an ammeter, a phase angle meter, a frequency generator, and a variable power supply, thereby providing for a variety of signals and analyses to be performed on a unintentionally grounded circuit in an ungrounded AC or DC power distribution system. The ground fault detection and location apparatus is capable of operating in six different modes, with each mode providing a different capability or opportunity for detecting, analyzing, and locating one or more unintentionally grounded circuits in an normally ungrounded AC or DC power distribution system.

Abstract: An electric vehicle incorporates a ground fault detecting system for preventing a ground fault detector from detecting a ground fault in error. First and second ground fault detectors are associated respectively with first and second ungrounded power supplies which generate respective different voltages. Since the first and second ground fault detectors are activated in different periods, the ground fault detecting system prevents a ground fault from being detected in error.

Abstract: A method is provided for detection of a ground fault in a high resistance network in a voltage source power conversion circuit comprising a power converter that converts incoming AC power to DC power applied to a DC bus and an inverter that converts DC power from the DC bus to output AC power. The method includes detecting a midpoint-to-ground voltage between a low side of the DC bus and a ground potential and detecting the presence of a ground fault in a high resistance network based upon the detected midpoint-to-ground voltage.

Abstract: A system and method for the detection of plasma excursions, such as arcs, micro-arcs, or other plasma instability, during plasma processing by directly monitoring RF current just prior to reaching an RF power electrode of a plasma processing chamber is provided. The monitored RF current may be converted to an RF voltage and then passed through a succession of analog filters and amplifiers to provide a plasma excursion signal. The plasma excursion signal is compared to a preset value, and at points where the plasma excursion signal exceeds the preset value, an alarm signal is generated. The alarm signal is then fed back into a system controller so that an operator can be alerted and/or the processing system can be shut down. In one embodiment, the RF current amplified and converted to a digital signal for digital filtering and processing. In certain embodiments, multiple processing regions can be monitored by a single detection control unit.

Abstract: A signal generating circuit for detecting ground status includes a power supply input unit (A), a step down rectified power supply or DC power supply unit (C) in series. The DC power supply required by a signal detection and process unit (D) is obtained by the power supply input unit (A) passing through the step down DC power supply unit (C), and then a ground status signal is obtained and outputted via a resistor unit (B) and the signal detection and process unit (D) connected in turn.

Abstract: The present invention is directed to an electrical wiring device that includes at least one sensor that provides a sensor output signal corresponding to electrical perturbations propagating on the plurality of line terminals or the plurality of load terminals. A protective circuit assembly configured to detect a fault condition when the sensor output signal substantially corresponds to at least one predetermined fault criterion and generate a trip actuation signal in response thereto. A solenoid coil is configured to generate a trip actuation force in response to the trip actuation signal. A circuit interrupter assembly includes movable contacts configured to be driven into a tripped state in response to the trip actuation force. An automatic fault simulation circuit is configured to generate a self-test signal without execution of software code. The self-test signal is generated such that it is sensed by the at least one sensor if the at least one sensor is operational.

Abstract: There is described a method and a system for evaluating damage of a plurality of cells in an electrolyser. The method comprises acquiring a voltage for each one of the cells; comparing the voltage to at least two threshold voltage levels; classifying the cells as one of: severely damaged cells, non-severely damaged cells and undamaged cells, based on the comparison of the voltage with the at least two threshold voltage levels; and deactivating the cells classified as severely damaged cells from the electrolyser.

Abstract: Provided a ground leakage current measurement apparatus in an ungrounded DC power system including main and auxiliary electric lines includes: a switching unit configured to perform switching to supply measurement power to a main ground resistor and an auxiliary ground resistor by using power of the electric lines; a measurement unit connected between the switching unit and the ground and configured to measure at least one of main and auxiliary ground leakage currents; and a control unit configured to control the switching unit to discriminate a main ground leakage current operation and an auxiliary ground leakage current operation of the measurement unit.

Abstract: An apparatus for monitoring line voltage in a circuit breakor includes a controller configured to calculate a voltage difference between the neutral voltage and the AC line voltage of positive polarity based on a first signal and a second signal and assign, using a polarity signal, the voltage difference value to the AC line voltage of positive polarity and the second signal to the AC line voltage of negative polarity. Because the AC line voltage of positive polarity can be calculated based on the first signal and the second signal, the number of signals requiring A/D conversion is reduced, and the number of circuit components needed to measure the AC line voltage is reduced.

Abstract: For monitoring the isolation of an IT-grid with respect to ground, an inverter connecting a direct current side with an alternating current side of the IT-grid and a photovoltaic device on the direct current side of the IT-grid, at least one isolation resistance of the direct current side with respect to ground is monitored for falling below a resistance threshold value while the inverter is running, and additionally a leakage current via the inverter towards ground is monitored for exceeding a current threshold value.

Abstract: A self-test circuit is provided that includes a signal circuit adapted to periodically output a circuit inhibitor signal to inhibit a breaking signal from a ground fault detector. The signal circuit is also adapted to periodically output a test signal simulating a ground fault. The self-test circuit also includes an alarm circuit adapted to receive an output signal from the ground fault detector in response to detecting the ground fault, and adapted to output an alarm when the ground fault detector is not operative. The signal circuit may be further adapted to periodically output a second test signal simulating a grounded neutral condition. A ground fault circuit interrupter system and a method are also provided.

Abstract: A first amplifier is arranged to receive a first signal from a first bus terminal. A second amplifier is configured to receive a second signal from a second bus terminal. An inverter input of an inverter is coupled to the output of the first amplifier. An input or inputs of an analog-to-digital converter are coupled to an inverter output of the inverter and the output of the second amplifier. The analog-to-digital converter is capable of producing a digital signal representative of the signals received from the first bus terminal and the second bus terminal. A data processor is capable of receiving an output of the analog-to-digital converter. The data processor is configured to apply one or more frequency domain transforms to the digital signal. The data processor identifies a circuit location of the ground fault or degraded isolation, a type of ground fault, or both based on the application of the frequency domain transform.

Abstract: A bus terminal is isolated from ground potential during normal operation of the vehicle. A first current is applied to the bus terminal. A current level detector is arranged to detect a first level of the first current, or a corresponding observed voltage level, that exists or flows from the bus terminal to ground. A compensator is configured to compensate for a range in the detected first level by applying a corresponding compensating voltage level to a first resistor coupled to the current level detector. An electronic data processor is capable of estimating a first isolation level between the bus terminal and ground based on the detected first level.

Abstract: A method and an apparatus for detecting a phase-to-earth fault on a three-phase electric line of an electric network, the apparatus determining a neutral admittance based on a ratio of a difference between zero sequence currents on the three-phase electric line and a difference between zero sequence voltages in the electric network before an earth fault and during the earth fault. The apparatus also compares the determined neutral admittance, to a predetermined operation characteristic to detect a phase-to-earth fault on the three-phase electric line. The predetermined operation characteristic, when presented on an admittance plane, defines a closed area such that the center of the closed area is offset from the origin of the admittance plane towards a negative susceptance direction and/or towards a negative conductance direction.

Abstract: A method is disclosed for monitoring galvanic isolation of a fuel cell device. At least one stack of fuel cells and at least one load circuit for fuel cells are arranged to an electrically freely floating configuration towards at least one structure near fuel cells. A controlled switching is performed via at least two switching points to at least one measurement element having known impedance in connection to the at least one structure. Measurements are performed from the measurement element to form voltage information. The voltage information and at least voltage information between switching points are processed to check floatages of fuel cells in relation to said at least one structure.

Abstract: A subsea line monitoring device comprising a diagnostic unit adapted to be deployed, in use, in a subsea location and having a first connector, the diagnostic unit being operable, in use, to output a signal indicative of the integrity of a line or device connected to the first connector.

Abstract: A method of determining a differential power condition includes comparing a voltage across a resistor to a first threshold. The voltage across the resistor is proportional to a difference between a first current and a second current. The method also includes comparing a difference between the first current and the second current to a second threshold. A differential power condition is determined in response to the voltage across the resistor exceeding the first threshold, the difference exceeding the second threshold, or both.

Abstract: A method for locating phase to ground faults in DC distribution systems. The method includes utilizing wavelet analysis using Multi-Resolution Analysis (MRA) as a signal processing tool for recognition of characteristic features in the voltage signal. The voltage signal contains characteristic information in the high frequency range above the switching frequencies of the PE converters which allows for localization of the fault.

Abstract: Device, system and method for monitoring lines of grounding electrodes, this invention deals with a system and a device for monitoring lines of grounding electrodes in transmission systems of electric power in direct current.

Abstract: Method and apparatus for measuring an earth fault current in an output circuit of an inverter (INU) operating on the PWM principle and forming alternating-current voltage from direct-current voltage, the output currents (iU, iV and iW) of which inverter are measured, and which inverter comprises at least two phase switches implemented with power semiconductor components (V1-V6, D1-D6), which switches, controlled by a control unit, connect their own output phases to a positive (+) pole and to a negative (?) pole of a direct-current voltage source such that the phase switches are repeatedly both in different positions and also in the same positions, wherein the results of current measurement during two opposite switch position combinations are recorded in memory, and the earth fault current is calculated by forming a difference of the measurement results of said combinations.

Abstract: A ground fault detection circuit for detecting ground faults in electrical subsea conductor lines including a first electrical conductor line, a second electrical conductor line, a first ground fault detection line, and a second ground fault detection line. The ground fault detection circuit further includes a first resistor operatively connected to a voltage source and the first ground fault detection line, a second resistor operatively connected to the voltage source and the second ground fault detection line, and a voltage detection device configured to detect the voltage at an output end of the first resistor to determine the presence of a ground fault in at least one of the first and second conductor lines.

Abstract: A method of detecting a ground fault condition between a direct current power system and the chassis ground of an electric or hybrid-electric vehicle is provided. The method includes sequentially opening and closing a first switch connected between a positive node of the direct current power system and the chassis ground of the vehicle and a second switch connected between a negative node of direct current power system and the chassis ground. The sequential opening and closing of the first and second switches charges and discharges an inherent capacitance present between the metal components of the direct current power system and the chassis. First and second currents are created as the inherent capacitance is charged and discharged. Measurements of the created first and second currents are then used to determine whether a ground fault condition exists between the direct current power system and the vehicle chassis ground.

Abstract: An apparatus and method for a supervisory circuit for a ground fault detection device or a ground fault circuit interrupt (GFCI) device is disclosed in which a low voltage DC power supply is used to generate a test stimulus signal for a self test of the GFCI device. The GFCI device includes line and neutral conductors configured to connect an AC power source and a load. A differential current transformer includes a toroid, through which the line and neutral conductors pass, and a secondary winding wound on the toroid. A differential ground fault detector is electrically connected to the secondary winding of the differential current transformer to compare current generated in the secondary winding from an imbalance of magnetic flux in the toroid to a trip threshold. A wire conductor is routed through the toroid of the differential current transformer. A controller is configured to control a low voltage DC test stimulus signal to be generated in the wire conductor.

Abstract: An apparatus and method for a supervisory circuit for a ground fault detection device or ground fault circuit interrupt (GFCI) device is disclosed in which is a test stimulus signal for a self test of the GFCI device is generated on a second secondary winding on a toroid of a differential current transformer. The GFCI device includes line and neutral conductors configured to connect an AC power source and a load. A differential current transformer includes a toroid, through which the line and neutral conductors pass, a first secondary winding wound on the toroid to generate a current in response to an imbalance of magnetic flux in the toroid, and a second secondary winding wound on the toroid. A differential ground fault detector is electrically connected to the first secondary winding of the differential current transformer to compare current generated in the secondary winding to a trip threshold.

Abstract: Methods and apparatus to facilitate ground fault detection with a single coil and an oscillator are disclosed. An example ground fault detection device includes a sense coil including a secondary winding surrounding a line conductor and a neutral conductor, the line conductor and the neutral conductor forming a primary winding. The example ground fault detection device also includes a voltage oscillator connected in series with the secondary winding to drive an oscillation component, and at least one of a detector or an amplifier connected in series with the secondary winding to detect at least one of a neutral-to-ground fault or a line-to-ground fault.

Abstract: A method for monitoring electric isolation of a high voltage DC bus to detect ground isolation faults includes monitoring voltage differentials between a positive DC electric power bus and a negative DC electric power bus and a chassis ground. Electrical isolation between each of the positive and negative DC electric power buses and the chassis ground is monitored using a ratio of the voltage differentials.

Abstract: An integrated ground fault detection circuit in accordance with an embodiment of the present application includes a shunt resistor provided on a positive rail of a DC bus, a high voltage pocket including a sensory circuit connected to the shunt resistor and operable to detect a fault condition indicating a short circuit and a transmitter section operable to continuously transmit a fault condition signal indicating the fault condition and a low voltage pocket including a receiver operable to receive the fault condition signal from the sensory circuit and a logic unit, connected to the receiver, and operable to provide a fault output signal indicating the presence of a fault condition based on the fault condition signal.

Abstract: Systems and methods for improved Variable Speed Drives are provided. One embodiment relates to apparatus for common mode and differential mode filtering for motor or compressor bearing protection when operating with Variable Speed Drives, including conducted EMI/RFI input power mains mitigation. Another embodiment relates to a method to extend the synchronous operation of an active converter to the AC mains voltage during complete line dropout. Another embodiment relates to an active converter-based Variable Speed Drive system with Improved Full Speed Efficiency. Another embodiment relates to a liquid- or refrigerant-cooled inductor. The liquid- or refrigerant-cooled inductor may be used in any application where liquid or refrigerant cooling is available and a reduction in size and weight of a magnetic component is desired.

Abstract: A leak detecting circuit includes: a current path having one end connected to a conductor housing a device supplied with a direct-current voltage from a direct-current power source, and having another end connected to a negative electrode of the direct-current power source; the current path including a limiting resistance for limiting a current, a switch element having a first electrode, a second electrode, and a control electrode, conduction between the first electrode and the second electrode being controlled, a detecting resistance for detecting a current flowing through the current path, and a variable direct-current power source allowing a plurality of leak detecting reference voltages for detecting a leak to be selected, and having a negative electrode connected to the negative electrode of the direct-current power source; an amplifier for amplifying a voltage across the detecting resistance; and a constant-voltage circuit for making constant a potential difference between a voltage of the control elect

Abstract: A control apparatus for a multiphase AC electric motor having an inverter includes a current control including an abnormal-state current controller; an abnormal-state detector that detects an abnormal state of any of a wire of an electric motor, a wire of an inverter, and a wire connecting the electric motor to the inverter as an abnormal phase; and an abnormal phase disconnect. The abnormal phase disconnect disconnects one or more of phases detected to be in an abnormal-state and the abnormal-state current controller generates an abnormal state voltage command in accordance with detection of an abnormal state, and uses phases other than the disconnected phases of the inverter to control individual currents of the phases, with the abnormal-state voltage command used as a multiphase voltage command.

Abstract: An apparatus includes at least one Rogowski coil and a processor. The at least one Rogowski coil is positioned within an electrical power distribution network to detect a first traveling wave current caused by a fault on an electrical power transmission line of the network, generate a first signal indicative of detection of the first traveling wave, detect a second traveling wave current caused by the fault on the transmission line, and generate a second signal indicative of detection of the second traveling wave. The processor is adapted to receive the first signal and the second signal and to determine, based on the first signal and the second signal, where on the transmission line the fault occurred.

Abstract: A ground fault detection device includes a sense coil including a primary winding and a secondary winding to detect current in a line conductor and a neutral conductor. It also includes a capacitor in parallel with the secondary winding and a virtual inductor to form a resonance circuit having a signal proportional to the current and being indicative of a ground fault condition.

Abstract: The present invention is to provide a power supply control apparatus which can connect a ground to a suitable electric potential when the ground is disconnected. The power supply control apparatus includes a control circuit having a switch element and a switch control unit, and a load. One terminal of load is connected to a direct-current power supply through the switch element, and the other terminal is connected to a ground electric potential. The switch control unit has a ground terminal connected to the ground electric potential and outputting a ground current flowing toward the ground electric potential. The control circuit includes a bypass device having a load side bypass system for passing the ground current to the ground electric potential through the load when connection between the ground terminal and the ground electric potential is disconnected.

Abstract: A ground fault detection system is provided. The ground fault detection system includes a magnetic core having first and second primary legs and a secondary leg disposed between the first and second primary legs. The ground fault detection system also includes first and second primary windings disposed around the first and second primary legs respectively and configured to introduce current in the first and second primary legs. Further, the ground fault detection system includes first and second secondary windings disposed around the first and second primary legs respectively and configured to detect a ground fault based upon a magnetic flux generated in response to the introduced current.

Abstract: A method for monitoring an insulation fault in an electric network with at least one electric power system supplying electric power to one or more electric loads, and at least one insulation resistance monitor is provided, wherein the at least one electric power system includes at least one electrical power source, and wherein the at least one insulation resistance monitor monitors an insulation resistance between terminal leads of the at least one electric power source and at least one reference potential. The steps are performed of disconnecting the at least one electric power source from the one or more loads by opening each terminal lead; measuring the insulation resistance between the electric circuit of at least one electrical power source and the reference potential; measuring the insulation resistance for the total electric network; closing the second terminal lead with the first terminal lead open; and measuring the insulation resistance for the total electric network.

Abstract: Systems, methods, and devices are disclosed, including a ground-fault sensor that has a plurality of conductors each disposed one inside of another except for an outer conductor and a field sensor configured to sense an electric field, a magnetic field, or both. In some embodiments, the field sensor is disposed adjacent the outer conductor.

Abstract: Systems, methods, and devices are disclosed, including a ground-fault sensor that has a plurality of conductors each disposed one inside of another except for an outer conductor and a field sensor configured to sense an electric field, a magnetic field, or both. In some embodiments, the field sensor is disposed adjacent the outer conductor.

Abstract: A current sensor assembly used for detecting ground faults, which includes an enclosure surrounding the current sensor for focusing the magnetic flux produced by conductors passing through the current sensor assembly away from the conductors, thereby reducing load-shift error and producing more accurate current readings for ground-fault sensing. The enclosure has two half members that are secured together to form a toroid-shaped shell that surrounds a toroidal core of the current sensor. A secondary winding and an optional test winding is wound around the toroidal core, and the ends of these windings exit one or more apertures formed in the enclosure. The half members have rounded profiles where the flat surfaces transition into different planes so that the magnetic flux does not encounter any sharp edges or transitions inside the enclosure as the flux flows away from the conductors.

Abstract: A device and method to determine the presence of a ground fault that distinguishes between the capacitive portion of the currents to ground, and the resistive portion of the currents to ground by ascertaining aspects of the voltage and residual current waveforms.

Abstract: A ground return path is determined to be impaired when no zero-sequence current is measured in the neutral return path, but zero-sequence current is detected in other suitable measuring points that include the windings of an autotransformer, or in a magnetically coupled delta-configured tertiary winding, or potential transformer.

Abstract: An apparatus including a monitoring unit, a number of sensor units, a number of cables, and a number of thermoelectric generators. The number of sensor units is capable of making measurements at a number of locations on a number of power lines for a number of loads. The number of cables connects the monitoring unit to the number of sensor units. The number of thermoelectric generators is capable of generating power for at least one of the monitoring unit and the number of sensor units. The monitoring unit is capable of receiving measurements from the number of sensor units through the number of cables. The monitoring unit is capable of determining whether an arc fault has occurred from the measurements received through the number of cables.