Abstract: Various systems, methods and apparatus are described for detecting an excessive or faulty ground current in a conductive wire or electronic device. A ground current detector is coupled to a known earth ground to determine whether other ground lines are carrying excessive, faulty and/or leaking currents. If these types of unsafe conditions are detected, then a user can take appropriate action to locate and correct these problems.

Abstract: A metering device of a power substation and method are provided for operating on a secondary analog waveform output by a transformer assembly receiving a primary waveform. The method includes stepping down the secondary waveform and generating a corresponding output signal; operating on the corresponding output signal for generating a corresponding first digital signal having a value proportional to the corresponding output signal and within a first range; and operating on the corresponding output signal for generating a corresponding second digital signal having a value proportional to the corresponding output signal and within a second range. The method further includes processing the first digital signal and outputting a corresponding first output signal; processing the second digital signal and outputting a corresponding second output signal; processing the first and second output signals; and generating output corresponding to the processing of the first and second output signals.

Abstract: A system and a method for measuring leakage current in an electrical transmission network. The system contains a plurality of electric current measurement devices distributed along the electrical transmission network and at least one central controller. The current measurement devices measure the electric current substantially continuously or repeatedly and report to the central controller. The central controller performs analysis of the measurements of the electric current along the transmission network and calculates the leakage current.

Abstract: A testing system for a ground fault detection system of an electrical system of a machine is disclosed. The testing system has a low voltage power source, the low voltage power source capable of operation that is independent from a high voltage power source of the machine. The testing system also has a variable current source that is permanently connected to a positive voltage bus or to a negative voltage bus of the electrical system of the machine, where the machine operates self-sufficiently. The testing system also has a controller connected to the variable current source. The testing system also has an input device, where the input device is connected to the controller.

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: An electric vehicle incorporates a ground fault detecting system and has first and second ungrounded power supplies. The ground fault detecting system includes a first insulation resistance detector for detecting a first insulation resistance of the first ungrounded power supply with respect to a grounded region of the electric vehicle, and a second insulation resistance detector for detecting a second insulation resistance of the second ungrounded power supply with respect to the grounded region. The first insulation resistance detector and the second insulation resistance detector detect the first insulation resistance and the second insulation resistance at different times, respectively.

Abstract: Methods and systems are provided for detecting loss of isolation of a motor, connections, or phase cables while an AC motor is operating. The system includes a power supply that is substantially isolated from the ground or chassis having a power supply voltage, and a power inverter electrically coupled to the power supply. The power inverter is configured to provide AC current from the power supply in an AC phase at an AC terminal, with the phase having current at a fundamental frequency that controls the motor speed. An electric motor is electrically coupled to the AC terminal of the power inverter and has a chassis that is substantially electrically isolated from the AC terminal of the power inverter under normal operating conditions. A processor is configured to control the AC current provided by the power inverter. The processor is configured to receive a first voltage signal related to current flowing through a motor chassis.

Abstract: An inverter circuit includes plural pairs of third coils, in which adjacent third coils are serially connected to each other so as to offset AC voltage generated from the paired third coils, one end of the paired third coils being connected to ground. Input terminals of plural diodes are connected to one end of the paired third coils so as to generate the voltage detection value by detecting voltage generated from the paired third coils. A fault detector compares the voltage detection value generated from the diodes with a predetermined threshold value to detect a fault and generates the comparison result.

Abstract: An arc detection means for detecting arcs in a plasma process includes at least one comparator to which an evaluation signal such as an output signal or an internal signal of an AC generator relating to the output signal and a reference value are supplied. The comparator is connected to a logic component that generates a signal for an arc suppression device.

Abstract: Embodiments of the invention can include methods and systems for detecting rotor field ground faults in rotating machinery. In one embodiment, a system can include a rotor of the rotating machine comprising a plurality of field windings substantially disposed therein and a stator of the rotating machine comprising a plurality of stator windings substantially disposed therein, with an air gap existing between the rotor and the stator. The system can include a high-impedance grounding circuit at least temporarily connected between the rotor and a ground. Additionally, the system can include an air gap flux probe positioned at least temporarily between the rotor and the stator for measuring a magnetic flux density generated in the air gap during operation of the rotating machine. Finally, the system can further include an analyzer in electrical communication with the air gap flux probe for receiving an output of the air gap flux probe.

Abstract: A method for detecting stator ground faults in a generator is described. The method includes receiving a neutral voltage signal from a neutral point of a stator, receiving a plurality of terminal voltage and current signals from the stator, deriving a magnitude of a harmonic component from the neutral voltage signal, deriving a total complex power from the terminal voltage and current signals, calculating an expected value of a harmonic based on the complex power at a first time and a plurality of values of the complex power, where the values of the complex power are measured at times before the first time, and comparing the expected value and a measured value of the harmonic.

Abstract: Sensor device for a household appliance that includes a body (2), detector device to measure at least one variable of a fluid and which includes a conductivity sensor, and a printed circuit (3) that receives the variables measured by the detector device. The body (2) includes a housing (20) where the printed circuit (3) is housed, and the device (1) also includes a cover (6) to close the housing (20). The body (2) also includes an inlet conduit (21) and an outlet conduit (22) through which said fluid passes, the housing (20), the printed circuit (3) and the cover (6) being disposed transversally to the conduits (21, 22) between the conduits (21, 22). The conductivity sensor is connected to said body (2) and is connected to or next to the printed circuit (3).

Abstract: A testing system for a ground fault detection system of an electrical system of a machine is disclosed. The testing system has a low voltage power source, the low voltage power source capable of operation that is independent from a high voltage power source of the machine. The testing system also has a variable current source that is permanently connected to a positive voltage bus or to a negative voltage bus of the electrical system of the machine, where the machine operates self-sufficiently. The testing system also has a controller connected to the variable current source. The testing system also has an input device, where the input device is connected to the controller.

Abstract: Various systems, methods and apparatus are described for detecting an excessive or faulty ground current in a conductive wire or electronic device. A ground current detector is coupled to a known earth ground to determine whether other ground lines are carrying excessive, faulty and/or leaking currents. If these types of unsafe conditions are detected, then a user can take appropriate action to locate and correct these problems.

Abstract: A circuit arrangement with a multi-wire line for supplying current to a sensor and for emitting a signal that corresponds to a measured value to an evaluation module via a signal line. To eliminate measuring errors caused by short circuits, first and second resistors, with the second resistor provided with a current tap, and a transistor, which is connected to a clock-pulse generator that bridges the first resistor in a clocked manner, are connected in series to the signal emission line. A comparator for comparing the values obtained via the resistors in the successive switching positions of the transistor and for emitting a short-circuit error message to the evaluation module, if the measured values differ in the successive clock pulses, is connected downstream of the resistors.

Abstract: A system, apparatus, and method (10) for detecting an electrical short condition in a dynamoelectric machine are described. The method includes determining an operating parameter of a dynamoelectric machine (14) responsive to at least one output signal of the dynamoelectric machine and providing a transfer function (16) for predicting a field current of dynamoelectric machine. The method also includes obtaining a value for a predicted field current (18) of the dynamoelectric machine from the transfer function and the operating parameter and identifying a shorted turn condition of the dynamoelectric machine responsive to a difference between the value of the predicted field current and a value of an actual field current of the dynamoelectric machine (24).

Abstract: There is provided a detector for detecting a layer short of a field winding in operation by measuring, with a field detector, a magnetic field generated from a field winding of an electric rotating machine. In the present invention, a field detector is installed outside an electric rotating machine to measure a leakage flux at the installation point to detect layer short by detecting the increase in a leakage flux or asymmetry of waveform of the leakage flux at an occurrence of a layer short of a field winding thereof, simplifying installation and enabling installation without halting operations of an electric rotating machine.

Abstract: A metering device of a power substation and method are provided for operating on a secondary analog waveform output by a transformer assembly receiving a primary waveform. The method includes stepping down the secondary waveform and generating a corresponding output signal; operating on the corresponding output signal for generating a corresponding first digital signal having a value proportional to the corresponding output signal and within a first range; and operating on the corresponding output signal for generating a corresponding second digital signal having a value proportional to the corresponding output signal and within a second range. The method further includes processing the first digital signal and outputting a corresponding first output signal; processing the second digital signal and outputting a corresponding second output signal; processing the first and second output signals; and generating output corresponding to the processing of the first and second output signals.

Abstract: The present invention is directed to a ground-current isolating circuit for providing a low voltage barrier between a service neutral conductor and an associated grounding system. The voltage barrier circuit comprises a first current unidirectional element and a second current unidirectional element connected in antiparallel. The unidirectional elements are preferably diodes having a characteristic threshold voltage. The current in a forward biased direction is blocked by the circuit until an applied forward biased voltage exceeds the threshold voltage. The present invention also is directed to a method of isolating a neutral conductor temporarily from an associated grounding system during testing of a structure grounding system.

Abstract: The present invention is directed to a circuit and method for self-testing a protection device for use in an AC power distribution system. The device is configured to be coupled between an AC power distribution system and at least one load. The method includes the step of introducing a simulated ground neutral fault during a first predetermined half cycle half cycle of the AC power. An attempt is made to detect the introduced simulated grounded neutral fault during the first predetermined half cycle half cycle. A fault condition is signaled if the introduced simulated grounded neutral fault is not detected within a predetermined period of time.

Abstract: A method for detecting stator ground faults in a generator is described. The method includes receiving a neutral voltage signal from a neutral point of a stator, receiving a plurality of terminal voltage and current signals from the stator, deriving a magnitude of a harmonic component from the neutral voltage signal, deriving a total complex power from the terminal voltage and current signals, calculating an expected value of a harmonic based on the complex power at a first time and a plurality of values of the complex power, where the values of the complex power are measured at times before the first time, and comparing the expected value and a measured value of the harmonic.

Abstract: A system for use in ac to ac or dc to ac power conversion equipment to detect faults in an inverter when the inverter is in a high impedance mode. The system detects ground faults or cross wiring conditions by converting the inverter outputs to digital signals and evaluating the frequencies of the resulting signals. The system keeps the inverter in the high impedance mode until after it has been determined that neither of the described abnormal statuses exist. The system tests for both of the abnormal statuses on power up and thereafter tests only for a ground fault whenever the inverter switches are disabled.

Abstract: The invention is based on a circuit arrangement for the detection of a leakage current or defect current, by means of which the power supply of an electronic circuit can be switched off. It is suggested that a track conductor connected with a signal line or an insulation-layer-free conductor connected with a signal line or an insulation-layer-free part of the signal line itself is arranged such that it crosses a potential leakage or defect current connection path of a short circuit between the power supply lines.

Abstract: A connector assembly for a wriststrap jack is provided wherein the jack may be easily replaced in accordance with the invention.

Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.

Abstract: A method is provided for detecting electrical leakage between a power supply and a frame of a vehicle or machine. The disclosed method includes coupling a first capacitor between a frame and a first terminal of a power supply for a predetermined period of time. The current flowing between the frame and the first capacitor is limited to a predetermined current limit. It is determined whether the voltage across the first capacitor exceeds a threshold voltage. A first output signal is provided when the voltage across the capacitor exceeds the threshold voltage.

Abstract: Method, apparatus and computer-readable code are provided for detecting a location of an incipient ground fault in an electrical propulsion system of a relatively large land-based vehicle, such as a locomotive. A method embodying aspects of the present invention allows to simultaneously apply a forcing function to one or more electrical devices connected to a direct current (dc) bus. The forcing function is configured to magnify (without voltage stress to such devices) an incipient ground fault that may be directly associated with a given electrical device. This enables to quickly identify the incipient ground fault and to uniquely identify the electrical device likely to be experiencing the incipient ground fault.

Abstract: Disclosed is a method of diagnosing inverter trouble capable of improving convenience of use and safety of the user by notifying the user of the error of switching devices used for outputting AC voltage of the inverter and the earth fault of an output of the inverter when applying power to the inverter.

Abstract: A system is provided for remotely detecting and locating damaged conductors. The system includes at least one slave controller disposed proximate at least one load and electrically connected to the loads via at least one conductor. The slave controller includes at least one solid-state switch capable of controllably altering the input current to the loads, as well as at least one measuring element for measuring at least one parameter associated with the loads and the solid-state switches. The solid-state switch can controllably alter the input current to the loads according to the parameters. The system also includes at least one damaged wire detector electrically connected to the conductors between the slave controller and the loads. The damaged wire detector is capable of detecting and/or locating at least one damaged conductor.

Abstract: An apparatus for electrical protection of an electrical system includes a protection circuit for detecting when silicon controlled rectifier (SCR) or other control elements in an engine driven generator of a welding-type power source have failed. In such an apparatus, a shorted rectifying control element detection device has an input stage connected to an engine driven generator that supplies power for a welding-type process and a filtering stage to bandpass current signals acquired by the input stage from the engine driven generator. The apparatus further has an output stage connected to the filtering stage that at least indicates a fault condition if fundamental frequency components present in the current signals exceed a threshold.

Abstract: Discloses is a method and a corresponding apparatus for monitoring operation of electrical household appliances (such as a freezer). The method includes checking the temperature inside the freezer on a periodical basis and comparing with a de-frosting temperature. A critical condition is detected and recorded when the temperature inside the freezer stays over the de-frosting temperature for a period longer than a threshold value. In this way, when a user returns home after several days of absence, he or she is informed whether the food has been de-frozen and then frozen again because of a outage in the power supply network.

Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.

Abstract: A welding system having a welding gun, comprising a casing that is grounded through a ground conductor, and a monitoring device, which detects the resistance of the ground conductor. A blanking device deactivates the monitoring device during the welding operation to reduce the danger of shut-downs through the ground integrity monitor. It is proposed to either deactivate the measuring circuit of the ground integrity monitor or to switch off the welding power interruption associated therewith as long as a welding current may flow or is flowing through the ground conductor. The monitoring device is deactivated or blanked out only for an essentially negligible fraction of the entire time, and there is no danger of any impairment of safety due to this short-term deactivation.

Abstract: A ground detection apparatus for electric automobile having a high-voltage DC power supply (31) which is electrically insulated from a body and a three-phase AC motor (33) which is driven by a DC voltage from the high-voltage DC power supply. A ground detection signal consisting of a square waveform is supplied to the DC power supply circuit through a detection resistor and a coupling capacitor, a voltage amplitude of a ground detection point serving as a connection point between the detection resistor (3) and the coupling capacitor (4) is detected, the detected voltage amplitude is converted into an insulation resistance on the basis of the relationship between a preset voltage amplitude and a preset insulation resistance, and levels of insulation resistance deterioration of the high-voltage DC power supply are detected by comparing the converted insulation resistance with a preset ground decision threshold value.

Abstract: An automated tool for performing an EL CID inspection of the step iron region of a generator stator that can be employed with the rotor in place. The tool has a track that is axially cantilevered at one end and supported magnetically within a stator slot adjacent the region to be monitored. The track has a smoothly rounded contour that approximately conforms to the profile of the stator step region. A carriage carrying a pickup coil is slideably mounted on the track and is driven back and forth along the track over the area to be inspected by a remotely-operated drive system. A video camera is mounted on the track and provides a remote visual indication of the location of the carriage relative to the stator.

Abstract: In one embodiment, an AC ground fault detector system senses an AC signal indicative of an unintended electrical path between a load driven by a power source and a reference potential using a capacitively coupled circuit.

Abstract: Systems and methods for locating any grounded circuit on an ungrounded AC or DC system without de-energizing the circuit, and enabling isolation of the grounded component of the circuit. A load is fed through an isolation device, such as a transformer for AC systems or a DC-to-DC converter for DC systems, and isolated from the normal distribution system without ever being de-energized. Once the isolating device is paralleled with the normal source for the load, the normal source is removed, leaving the load energized and fed by the isolating device. A ground detector relay is added at the secondary side of the isolation device to detect unwanted grounds along with a ground locating method to isolate the source of the ground, such as by oscillating the ground current. Once the grounded circuit is located, further troubleshooting may be performed to isolate the grounded component.

Abstract: The present invention relates generally to a protection circuit for electrical apparatuses, and more particularly, to a method and apparatus for detecting when silicon controlled rectifier (SCR) or other control elements in an engine driven generator of a welding-type power source have failed.

Abstract: A method and system for operating an electrical system including an electrical machine to predict an incipient fault in the electrical machine. A neutral-to-ground leakage signal representative of current between a neutral point of the machine and an electrical ground is generated and stored in a memory. If the leakage signal exceeds a selected threshold, the electrical system is operated at a reduced power condition to control the current. Temperature criteria of the electrical system at which any moisture that could cause the high leakage current is determined with a temperature sensing system and the temperature is monitored and compared to the selected temperature criteria. The electrical system returns to operations at normal power conditions if the leakage signal returns to within the selected threshold. The leakage current signal information stored in the memory is analyzed to predict an incipient fault in the electrical system.

Abstract: A transverse induction logging tool having a transmitter and receiver for downhole sampling of formation properties, the tool having a symmetrical shielded split-coil transmitter coil and a bucking coil interposed between the split transmitter coils to reduce coupling of the transmitter time varying magnetic field into the receiver. The tool provides symmetrical shielding of the coils and grounding at either the transmitter or receiver end only to reduce coupling of induced currents into the received signal. The tool provides an insulator between receiver electronics and the conductive receiver housing having contact with conductive wellbore fluid, to reduce parasitic current flowing in a loop formed by the upper housing, feed through pipe, lower housing and wellbore fluid adjacent the probe housing or mandrel. An internal verification loop is provided to track changes in transmitter current in the real and quadrature component of the received data signal.

Abstract: A method for locating a speed sensitive ground condition in a field winding of an electromagnetic synchronous machine having a rotor and an excitation circuit, the method including: sensing a magnetic flux generated by the field winding, while accelerating the rotor and activating the excitation circuit; detecting a cyclical aberration in the magnetic flux occurring during revolution of the rotor, and determining a position in the field winding corresponding to the cyclical aberration and identifying that position as a location of the speed sensitive ground condition.

Abstract: An air conditioner includes an air conditioning unit, and three wiring lines for supplying power to the air conditioning unit. The three wiring lines are a pair of single phase AC power lines and an earth line which are to be connected to three source lines. The three source lines are a pair of single phase AC source lines and a ground line. The air conditioner also includes a detection unit including a detecting device that detects voltages between each of the AC power lines and the earth line, a conversion device that converts the voltages detected by the detecting device into logic level signals, a comparator that determines presence or absence of faulty connection between the three wiring lines and the three source lines by comparing the logic level signals obtained by the conversion device with reference logic level signals, and an output device that shows a result of determination made by the comparator.

Abstract: The invention provide a cost effective way of determining the status of a light emitting device, such as a light emitting device in a non-emitting display device. The apparatus includes a plurality of light emitting devices arranged in a predefined configuration, a voltage supply coupled to the light emitting devices for making a current flow through the light emitting devices, and electrically conductive devices positioned a predetermined distance away from the light emitting devices, wherein each of the electrically conductive devices generates a voltage in response to current flowing through one of the light emitting devices. An AND gate coupled to the electrically conductive devices receives the voltage from each of the electrically conductive devices through an input and generates an output. A status determining device coupled to the output of the AND gate determines the status of the light emitting devices based on this output.

Abstract: An automated tool for performing an EL CID inspection of the step iron region of a generator stator that can be employed with the rotor in place. The tool has a track that is axially cantilevered at one end and supported magnetically within a stator slot adjacent the region to be monitored. The track has a smoothly rounded contour that approximately conforms to the profile of the stator step region. A carriage carrying a pickup coil is slideably mounted on the track and is driven back and forth along the track over the area to be inspected by a remotely-operated drive system. A video camera is mounted on the track and provides a remote visual indication of the location of the carriage relative to the stator.

Abstract: Monitoring a leakage current from an isolator for a high voltage conductor to ground includes directing the leakage current through a primary wire inductively coupled to a secondary winding energizing an amplifier.

Abstract: The present invention relates to a method and to a circuit arrangement (10) for the measurement of earth leakage in the current feeds in the intrinsically safe current supply (1) to the electronic control units (4) for underground mining installations and machines, whereby at least one earthed control unit is connected to the two intrinsically safe potentials of an intrinsically safe direct current supply (1) and at least one earth leakage sensor (20) is provided for earth leakage measurement with which steps of the periodical application of a test potential (Umess) from an intrinsically safe switchable test voltage source (21) to an RC-element (22), isolated from earth (8) by means of decoupling capacitors (C1, C2), measurement of the charging or discharging current behaviour of the RC-element (22) after each switching of the test voltage source (21) and comparison of the measured charging or discharging behaviour with stored reference data are made by means of a microprocessor (24) using stored reference da

Abstract: Methods and apparatus to detect terminal open circuits and short circuits to ground in inductive head write drivers are presented. A exemplary method is provided for detecting a short-circuit condition at at least one of a pair of write head terminals of a write driver, the write driver producing a write current that, when passed through a inductive head assembly coupled to the pair of write head terminals, polarizes the inductive head according to a direction of the write current. The method includes the step of generating a first current that is proportional to at least a portion of the write current that flows in a first direction into a first write head terminal of the write driver. A second current is generated that is proportional to at least a portion of the write current that flows in a second direction, opposite the first direction, into a second write head terminal of the write driver.

Abstract: A leak detection method for electrical equipment provided with an electric motor, includes the step of detecting, during non-energization of the motor, a voltage generated in a voltage-dividing resistor provided between a winding of the motor and ground, thereby detecting leak produced in the motor.

Abstract: An electrical system and a sensor for on-line monitoring of the state of high-voltage insulation in the electrical system. In this arrangement, the signals associated with partial discharge activity are monitored and transmitted from the sensor to monitoring instrumentation. The sensor is interconnected with the potential stress shield of existing bushings. The capacitance in the bushing between the main conductor and the stress shield conducts partial discharge current which is available for being sensed.

Abstract: An apparatus and method for detecting a short in a load which receives power from a transformer having a primary winding and a secondary winding with the load being connected to the secondary winding. The apparatus has a waveform conversion circuit, a phase detector circuit and a filter. The waveform conversion circuit converts voltage and current signals that represent the voltage and current, respectively, of the primary winding into generally squarewave voltage and current signals, respectively. The phase detector circuit outputs a control signal having a first state when the generally squarewave voltage and current signals are substantially in phase and a second state when there is a difference in phase between the generally squarewave voltage and current signals that is greater than a predetermined phase difference. The filter filters the control signal outputted to the phase detector circuit.