Abstract: Wiring defects are located by detecting a reflected signal that is developed when an arc occurs through the defect to a nearby ground. The time between the generation of the signal and the return of the reflected signal provides an indication of the distance of the arc (and therefore the defect) from the signal source. To ensure arcing, a signal is repeated at gradually increasing voltages while the wire being tested and a nearby ground are immersed in a conductive medium. In order to ensure that the arcing occurs at an identifiable time, the signal whose reflection is to be detected is always made to reach the highest potential yet seen by the system.

Abstract: A method for the early detection of faults in an electric supply system, comprising the steps of continuously checking the existence of RF transients on the electric supply system line, transforming detected transients whose amplitude is above a predetermined level, into a sequence of pulses, analyzing the temporal spacing between pulses to identify those which are due to dimmers, and disregarding them, identifying short-noisy states structures in said sequence, states whose duration is shorter than a period T-ARC, determining short-noisy states where the current amplitudes before and after said states are different, and disregarding these states considered to be caused by normal switching operations, regarding each of the remaining short-noisy states as a faulty event and accumulating such events in a first register, identifying separately long-noisy states in said sequence, states whose duration is longer than a period T-ARC, ascribing a number of arcing events to each long-noisy state proportional to its d

Abstract: A method and apparatus for detecting electrical arcs in an electrical system having a periodic power supply is disclosed. A method according to the invention compares instantaneous values of a monitored waveform both with (a) their past values at corresponding phases of the AC supply waveform, and (b) their future values at corresponding phases of the AC supply waveform. The monitored waveform is delayed or stored to allow such comparisons in near real time, to produce an output which is only slightly delayed behind the monitored waveform. An apparatus according to the present invention discloses a sampling circuit that samples electrical signals indicative of transient load conditions to produce a sampling circuit output. A storage device receives the sampling circuit's output and stores a time history of that output over an interval.

Abstract: The present invention provides a method and device for detecting a discharge in an electrical device comprising, providing a bushing having a bottom lower flange and a top upper flange, providing a shield inside the bushing extending from the bottom lower flange to a position at least below the top upper flange and providing an antenna outside the bushing at least above the position for measuring an output signal from the device for detecting the discharge.

Abstract: An assembly and method is provided for a tripping mechanism of an circuit breaker to limit the damage to a protected circuit breaker and other associated equipment such as enclosures, bus way, etc. from the high forces that result from high currents and prevent unwanted tripping of a circuit breaker due to rapidly decreasing currents. A trip system for a circuit breaker including a sensor to determine a rate of change in the current level. A positive detector is connected to the sensor to determine a positive current direction. A negative detector is connected to the sensor to determine a negative current direction. An electronic switch connected to the positive and negative sensors to activate the tripping mechanism of the circuit breaker. A power supply is connected to the tripping mechanism and electronic switch.

Abstract: Disclosed is a device for detecting a partial discharge of power equipment. EM (electromagnetic wave) sensors detect EM signals from a partial discharge in a metal clad switchgear, a power cable, and a GIS. EM detectors amplify the signals from the sensors, and output only noise-removed IF signals. A pulse generator integrates the IF-processed EM to compare the integrated value with a previous value, and outputs a pulse according to a partial discharge. An EM level processor compares the IF-processed EM with reference voltages to output EM pulses of a plurality of levels. A waveform shaper shapes the pulses. A controller calculates the average number of pulses per 1 cycle by counting the partial discharge pulses for a predetermined time, receives the waveform-shaped pulses to calculate the partial discharge amount, and transmits the calculated amount, combined with the average number, to an external monitoring system.

Abstract: An apparatus to detect a breakdown in the insulation of a through-bolt in a laminated generator core is provided. The apparatus provides a ground detection circuit to generate and sense a signal in response to a ground that develops as a result of a breakdown in through-bolt insulation. Preferably, the circuit includes a signal source that generates a signal in response to insulation breakdown and a signal sensor to sense the signal so generated. The apparatus, moreover, can identify which among a plurality of through-bolts has experienced an insulation breakdown. Methods also are provided for detecting a breakdown in through-bolt insulation and identifying which among a plurality of through-bolts has experienced a breakdown in insulation.

Abstract: A testing device for detecting and locating an arcing fault in an electrical system includes a detector circuit for detecting one or more characteristics of the arcing fault proximate the arcing fault and outputting a responsive signal. An annunciator speaker or display annunciates the responsive signal when the detector circuit is proximate the arcing fault, in order to locate the arcing fault in the electrical system.

Abstract: A system for arc detection testing using synthesized arcs is disclosed, which uses voltage and current waveform generators to generate an arc's analog form voltage and current waveform from a digital form of the arc's captured waveforms. A voltage waveform amplifier and a current waveform amplifier are included, with the outputs of the voltage and current waveform generators coupled to the input to inputs of the voltage and current waveform amplifiers, respectively. The outputs of the voltage and current waveform amplifiers are connected in circuit to a device under test to test the device's response to the waveforms. A method for testing a device's response to a simulated arcing condition is also disclosed. An electric arc's voltage and current waveforms are captured in digital form. Analog form voltage and current waveform are generated from the captured digital voltage and current waveforms.

Abstract: A partial discharge detection test link (20) and system detect partial discharge of a power cable at a power cable accessory (6). The power cable accessory includes a first accessory component and a second accessory component connected to each other. The partial discharge detection test link (20) is a permanent or temporary substitute for a conventional service link, connects directly across the power cable accessory and includes a conductor member (22) and a partial discharge sensor (24). The conductor member (22) has an electrically conductive element (26) and an insulation (28) surrounding and extending along the electrically conductive element. The electrically conductive element (26) is electrically connected directly between the first and second accessory components.

Abstract: Arcing faults in an electric power system are detected by sensors powered by the light generated by the arcing even in the presence of background light. The sensors have one or more first photovoltaic cells energized by light passed through a first filter having a passband which includes a characteristic wavelength of the arcing material to generate a sensed light electrical signal. One or more second photovoltaic cells are energized by light filtered by a second filter having a passband not including the characteristic wavelength to generate a background light electrical signal. These two electrical signals are applied in opposition to an LED which is turned on when arcing is present. The light signal from the LED is transmitted through an optic fiber to a photoelectric circuit, which generates an arcing signal when energized. The LED may be biased toward the on condition by unfiltered additional photovoltaic cells.

Abstract: An apparatus for detecting flaws in a tire. The apparatus may contain a frame sized to be placed in the interior of the tire, at least one device operably connected to the frame so that upon rotation of the tire the frame travels around the interior of the tire, where the frame is substantially supported by the tire, and at least one pin attached to the frame, where the at least one pin is adapted to be connected to a voltage generator to create an electric field near the surface of the tire when in use so that an electric arc is produced upon the presence of a flaw in the tire.

Abstract: An abnormal current discriminating method including an arc current detecting method and the apparatus for performing the same in which the arc current method includes the steps of: extracting a predetermined transition pattern specified by the combination of fluctuation patterns of peak values of three continuous half waves from the peak value for each half wave detected from an alternating current flowing to the AC load circuit which is sampled in a predetermined cycle and converted into a digital value, counting the number of appearances of the predetermined transition pattern, and comparing the count value with a predetermined threshold.

Abstract: An AFCI looks for a variation in the number of load current step pulses, i.e., di/dt pulses, occurring in a succession of power line intervals. A number of di/dt pulses occurring during one cycle of the power wave is compared to a number of di/dt pulses occurring in a subsequent cycle of the power wave. The AFCI activates when the number of times that the di/dt count varies from line cycle to subsequent line cycle exceeds a predetermined number within a predetermined number of line cycles. A counting window within each line cycle preferably extends from approximately 150 degrees after the start of the first half wave cycle to approximately 30 degrees after the start of the following half wave cycle, thereby placing the counting window in the band where light dimmers typically are not designed to operate.

Abstract: Particles in a fluid cause an arc at a certain electric field whose value depends on the nature of the particles (size, composition, and the like). By applying an electric field across the fluid and determining the value of the electric field at which the arc occurs, the nature of the particles can be determined. For example, if their composition is known, their size can be determined, and vice versa. The device for carrying out such testing has a first electrode with an interior opening and a second electrode having a pin through the interior opening to define a passageway for the fluid. The electric field is varied, either by varying a voltage applied between the electrodes or by forming the passageway to be tapered. Multiple such passageways can be provided, as by forming the first electrode from honeycomb-expanded metal, thus reducing pressure drop, energy consumption without decreasing sensitivity to low concentrations.

Abstract: Arcing in dc electrical systems subject to cyclic disturbances is detected by a current sensor, and a bandpass filter sensitive to arcing noise, which filters the sensor current. The absolute value of the bandpass filtered signal is integrated over repetitive intervals in a resettable analog integrator. A low cost microprocessor samples and resets the analog integrator at a frequency below the pass band and generates a time attenuated accumulation of the samples that produces an arcing signal if it reaches a predetermined limit. To improve nuisance immunity, the sensed dc current is compared in a high speed comparator to the average sensed dc current, and only samples taken by the microprocessor during a predetermined time period after the sensed dc current exceeds the average sensed dc current in a predetermined manner are accumulated. The average sensed dc current is also used by the microprocessor to provide overload protection.

Abstract: A signal obtained from the drive input of a motor or an insulated winding is applied to a sensor that strongly rejects high frequency drive signal components yet passes discharge signal components. This allows discharge signal components to be detected in the presence of harmonics of the drive signal. The voltage of the drive signal may be varied so that the lowest drive signal voltage producing a discharge event may be determined. That voltage is the motor or winding's corona inception voltage.

Abstract: Briefly stated, and in accordance with a presently preferred embodiment of the invention, an arc fault detecting circuit using, a pulse width modulation, or PWM, technique is used to sense series or parallel arc faults. When arc faults occur, typically an arc step in current is followed by broad band arc noise which is caused by the random fluctuations in arc column resistance. In this invention, a logic signal is created which has a duration or width that corresponds to the time interval during which the broad band arc noise generated by the arc is present. Typically an arc fault randomly starts, generates broad band arc noise, and then extinguishes as the next current zero cross of the AC load current is approached. The random start causes PWM of the logic pulse whenever the start of the arc randomly moves with respect to the current zero cross. An arc fault that randomly starts, and then randomly stops, will also cause PWM with respect to the zero cross.

Abstract: A device for detecting arc fault which distinguishes harmful arc from the signal generated by operation of a dimmer and start of electronic devices. Signals outputted from a current transformer is attenuated by a resistor which is coupled in parallel to the current transformer. By the attenuation of the resistor, the signal generated by the operation of a dimmer is not determined to be arc in arc determining part. Harmful arc and the signal generated by the start of the electronic device are distinguished by integrating both signals. As the harmful arc lasts for a long time, large signals are integrated in an integrator while the signal generated by the start of electronic device does not last for a long time.

Abstract: An ultrasonic RFI source locator implements signal analysis to discriminate ultrasonic shocks emanating from power line equipment sources from ambient and other interference sources, as well as distinguish between specific type interference sources, such as corona and sparking discharge. The locator has a directional or contact ultrasonic sensor for receiving a signal representing the ultrasonic shocks from a targeted source, and includes signal processing circuitry to detect and compare the strengths of portions of the sensed signal that are modulated at whole integer multiples (harmonics) of an electrical power frequency (e.g., at 60 Hz and 120 Hz on a 60 Hz A/C power system, or 50 Hz and 100 Hz on a 50 Hz A/C power system) with each other, with the total signal and with selected non harmonic frequencies. The locator provides an operator indication of the result of this spectral analysis.

Abstract: Disclosed is a semiconductor device capable of stabilizing a gate voltage at high voltage and high current, protecting the device from breakdown by preventing current nonuniformity and oscillations and the like, thereby improving reliability, and a method for controlling the semiconductor device.

Abstract: Arcing in dc electrical systems subject to cyclic disturbances is detected by a current sensor, and a bandpass filter sensitive to arcing noise, which filters the sensor current. The absolute value of the bandpass filtered signal is integrated over repetitive intervals in a resettable analog integrator. A low cost microprocessor samples and resets the analog integrator at a frequency below the pass band and generates a time attenuated accumulation of the samples that produces an arcing signal if it reaches a predetermined limit. To improve nuisance immunity, the sensed dc current is compared in a high speed comparator to the average sensed dc current, and only samples taken by the microprocessor during a predetermined time period after the sensed dc current exceeds the average sensed dc current in a predetermined manner are accumulated. The average sensed dc current is also used by the microprocessor to provide overload protection.

Abstract: A method for the early detection of faults in an electric supply system, comprising the steps of continuously checking the existence of RF transients on the electric supply system line, transforming detected transients whose amplitude is above a predetermined level, into a sequence of pulses, analyzing the temporal spacing between pulses to identify those which are due to dimmers, and disregarding them, identifying short-noisy states structures in said sequence, states whose duration is shorter than a period T-ARC, determining short-noisy states where the current amplitudes before and after said states are different, and disregarding these states considered to be caused by normal switching operations, regarding each of the remaining short-noisy states as a faulty event and accumulating such events in a first register, identifying separately long-noisy states in said sequence, states whose duration is longer than a period T-ARC, ascribing a number of arcing events to each long-noisy state proportional to its d

Abstract: By a test vessel, a test enclosure is created immediately surrounding the zone of the line or cable harness to be inspected by detection. This enclosure is sealed off before detection-inspection and an internal atmosphere is substituted by at least a partial gas substitution with a test gas or a test gas mixture with a lower disruptive discharge voltage than that of air. This test method permits detection of faulty lines with greater distances between the faulty line, the test electrode, and the corresponding counter-electrode. A corresponding pliers-type device for the sectional detection of a line or harness, or a stationary vacuum seal-tight testing chamber capable of performing the same detection may be used. The method is suitable also for a local detection when the test vessel is created and formed by the installation object itself (e.g., an aircraft fuselage).

Abstract: A method and an arrangement (300, 400) for separating partial discharge pulses originating from various partial discharge sources in an electric system, comprises the steps of measuring a variable of the electric system, such as voltage or current, to which partial discharges occurring in the electric system cause pulses, separating the pulses caused by partial discharges, i.e.

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: A device for detecting and locating arcs in a set of wires is discussed. The device comprises a probe for discharging controlled current to an exposed portion of a wire in the set of wires. The probe includes a handleable enclosure and an elongated structure which projects from the enclosure for conducting a gas and for enclosing a needle that has a tip. A suitable gas includes gases that have low electron attachment, such as helium. The device further comprises a control unit for communicating control signals as well as the gas to the probe. The control unit includes a controller, a valve being controllable by the controller and being capable of regulating the flow of the gas, and a high-voltage generator being controllable by the controller to generate a high-voltage signal, which can be communicated to the probe by the control unit.

Abstract: For an electrical system a sensor and associated circuits are provided for on-line monitoring of the state of the high-voltage insulation in the electrical system. In this arrangement, both the power frequency signal and of the radio frequency signals associated with partial discharge activity may be monitored and transmitted from the sensor to remote monitoring instrumentation. The sensor is disposed in a stand-off insulator which also may act to support the high voltage conductor system.

Abstract: The present invention provides a method of diagnosing a partial discharge in a gas-insulated apparatus and a partial discharge diagnosing system for carrying out the same to achieve highly accurate diagnosis through the detection of a partial discharge signal and diagnosing the partial discharge signal through multiple conditional branching. The partial discharge diagnosing system of the present invention consists: a partial discharge signal detector for detecting a partial discharge signal representing a partial discharge produced in the gas-insulated apparatus, a signal analyzer for receiving the partial discharge signal detected by the partial discharge detector and analyzing the partial discharge signal, a diagnostic unit for determining a cause of the partial discharge on the basis of results of analysis made by the signal analyzer, and a display unit for displaying results of diagnosis.

Abstract: An electrical discharge measurement device for non-contact measurement of an electrical discharge having a discharge magnitude. The electrical discharge causes a corresponding emission of optical radiation. The electrical discharge measurement device has a light-collecting device for forming an image from the optical radiation from the electrical discharge, and an optical filter operatively coupled to the light-collecting device for preferentially selecting wavelengths at which the electrical discharge emits relatively intense optical radiation. An optical detector receives light from the light-collecting device and filtered by the optical filter for converting the filtered light to an electrical signal. An electronic signal-processing device provides, based on the electrical signal, a quantitative discharge measurement related to the magnitude of the electrical discharge.

Abstract: A method for determining sources of interference that cause partial discharges in an encapsulated conductor structure of a magnetic resonance apparatus, particularly in a gradient coil. Under the method, a low-frequency high voltage is applied to a conductor, and signals resulting from an adjacent high voltage are measured within a frequency range located in the kHz range, particularly from 40 to 400 kHz. The signals are analyzed in order to determine partial discharges. The conductor is again charged with a low-frequency high voltage and additional signals are measured within a frequency range located in the MHz range, particularly from 10 to 300 MHz. The additional signals are analyzed in order to determine partial discharges.

Abstract: The invention relates to a method and apparatus for identification of the disconnection of a current protection device, in particular of a protection device which is connected in series with a semiconductor component and is arranged on a rotating shaft. According to the invention, electromagnetic pulses which are produced during disconnection of the current protection device are received by an antenna which is arranged in the vicinity of the protection device.

Abstract: A sputtering arc fault detector (10) for a system having an electrical conductor (14) carrying current to a load. The sputtering arc fault detector includes a current monitor (64) coupled to the conductor for generating a variable signal responsive to behavior of the current in the conductor. A level detector (58) is coupled to the monitor and generates a first pulse when the variable signal exceeds a first level. A step detector (62) is coupled to the monitor and is responsive to rapid step increases of the variable signal. The step detector generates a second pulse when the variable signal exceeds a second level. An arc verifier (48), which is coupled to the level detector and the step detector, combines the first and second pulses, and generates a fault signal when the combined pulses exceed a third level.

Abstract: A system for locating parallel arcing faults in a set of wires is described. The system includes three devices that can be used in combination or alone. A first device applies a current to a wire while grounding the remaining wires of the set of wires so as to cause the parallel arc, the first device being adapted to locate the parallel arcing fault using one or more leading edges of one or more electromagnetic waveforms being conducted on the wire under test. A second device comprises a controller and two or more receivers, each receiver being electrically coupled to the controller for receiving one or more leading edges of one or more electromagnetic waveforms being radiated by the parallel arcing fault. A third device senses one or more leading edges of one or more electromagnetic waveforms as well as the ultrasonic emissions emitted from the parallel arcing fault.

Abstract: Electric arc monitoring is effected by exploiting the discovery that electric arcs are fractal phenomena in that all essential information that signifies an “arc” is contained in each fractal subset. The fractal subsets are logarithmically distributed over the arc spectrum. Monitoring of arcs is most advantageously effected on a fractal subset of low logarithmic order where the amplitude is higher pursuant to the l/f characteristic of electric arcs, where cross-induction among neighboring circuits is lower, and where travel between the arc and the arc signature pickup is longer that at the high frequency customary for electric arc detection. Fractal subset information reduces the danger of false alarms. Arc signature portions may be processed in out of phase paths or treated as modulated carriers for monitoring.

Abstract: A method and an arrangement (300, 400) for determining the location of partial discharge sources in an electric system, the method includes the steps of measuring a variable of the electric system, such as voltage or current, to which partial discharges occurring in the electric system cause pulses, separating the pulses caused by partial discharges, i.e.

Abstract: A method and system for identifying, the cause of a partial discharge occurring in an electric system, which method increases measuring a variable of the electric system, such as voltage or current, to which partial discharges occurring in the electric system cause pulses, separating the pulses caused by partial discharges, i.e. partial discharge pulses, and occurring in the measured variable, defining and storing pulse parameters depicting the partial discharge pulses, or information from which the pulse parameters can be derived, defining (301) one or more pulse group graphs by means of the pulse parameters after at least a predefined number of partial discharge pulses, i.e.

Abstract: Signals representative of current and voltage in a circuit are processed and compared with stored temporal models models representative of arc faults and events not associated with arc faults. The models may be templates or stochastic models. Alternatively, the processed signals may be supplied to an artificial neural net programmed to recognize features of different arcs. An output may be provided to open a circuit breaker when an arc fault is detected.

Abstract: A combination AFCI/GFCI includes a single test button which when pushed, tests both the arc fault and ground fault detection circuitry and the circuit interrupter. Closing the test button causes a simulated ground fault and enables a signal steering circuit. The steering circuit redirects the ground fault detector output to an arc fault simulator circuit which produces a simulated arcing pulses that are coupled, preferably by way of an extra winding, to an arc fault sensor transformer. The arc fault detector senses the arc fault simulator pulses coupled to the sensor transformer and, if everything is operating normally, triggers a switching device such as an SCR which activities a circuit interrupter. In this way, both the ground fault circuit interrupter and arc fault circuit interrupter functions are tested simultaneously, and the test is initiated by a single test button.

Abstract: A sensor and associated circuits are provided for on-line monitoring of the state of the high-voltage insulation in electrical equipment with capacitance tap. In this arrangement, both the power frequency signal and the radio frequency signals associated with partial discharge activity are sensed. These signals are transmitted from the sensor to remote monitoring instrumentation via one connecting cable. The sensor contains a surge arrester in parallel with a capacitor shunt, a radio frequency current transformer and a connecting circuit. The polarity terminal of the primary winding of the radio frequency current transformer is connected to the tap output. The non-polarity terminal is connected to the common connection point of the surge arrester and the capacitor shunt while the second terminals of these components are connected to the local ground.

Abstract: A circuit switching device or circuit breaker with integrated self-test enhancements is disclosed having separable contacts operable under processor control to control power to a circuit responsive to at least one of a plurality of fault conditions and operable according to a method for testing, including the steps of: controlling the switching device during a sampling cycle, to input one or more operating parameters sensed in the circuit to an A/D converter for measurement wherein the operating parameters enable detection of the fault conditions; determining whether to read a select one of the operating parameters from an output of the A/D converter into a first memory; and reading pre-determined parameter values from a second memory into the first memory during the sampling cycle instead of the operating parameters read from the A/D converter if a self-test has been invoked during the sampling cycle.

Abstract: A device for measuring the AC voltage drop across a series of connections under load with no direct electrical contact to the conductors. The presence of a substantial resistance at series contacts is indicative of a series arcing fault. The device comprises a capacitive probe for clamping to the outer insulation layer of the wire to sense a first voltage at a first node. The device further comprises a floating high-impedance meter having a ground reference coupled to the source of common-mode voltage at a second node, the floating high-impedance meter being adapted to measure a voltage difference between the two nodes and being further adapted to indicate the presence of the series fault when the measured voltage exceeds a predetermined level.

Abstract: An insulated device diagnosing system is capable of judging the deterioration, lifetime, and defects of a device. The intensity at each voltage phase angle is measured at a plurality of specific frequencies, taking high voltage phase angles as the abscissas. The deterioration, lifetime, and the kind and extent of abnormality of the device are judged from the pattern and intensity of the spectral distribution, which is obtained by peak-holding the measured intensity for a defined time period. According to the present invention, partial discharge can be measured highly sensitively and precisely to diagnose the deterioration, lifetime and the extent of defect of the device. As a result, the insulation reliability of the device can be improved, and the part of the device that should be repaired/replaced can be grasped before disassembly of the device, thereby cutting the maintenance cost.

Abstract: A system is disclosed for monitoring electrical partial discharge signals in electrical power apparatus. The apparatus includes a housing and a plurality of openings in the housing through which electrical power may pass via electrical power contact units. The system includes a plurality of sensor units, each being in communication with, and associated with, an electrical power contact unit at each opening in the housing. The sensor units are for sensing partial discharge signals at each opening in the housing and for producing sensor output signals. The system also includes a control unit for simultaneously and synchronously receiving the sensor output signals over an interval of time, and produces simultaneous synchronous output signals. The system also includes a processing unit for processing the simultaneous synchronous output signals.

Abstract: A circuit for detecting arc faults and over-currents includes two overcurrent detection circuits and a ground fault circuit referenced to a single ground and configured to receive power from a single power supply. Each over-current detection circuit includes a Hall effect current sensor configured to determine a current in a corresponding pole conductor. A method for detecting arc faults and over-currents includes determining a current in a pole conductor using a sensor not in contact with the pole conductor. This circuit and method allow a two-pole breaker circuit to be configured in a form similar to a one-pole circuit and eliminate tripping caused by spurious signals from bimetal sensors.

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: Systems of monitoring electric arcs substantially eliminate alternating current fundamentals and harmonics from monitored arc signatures. Such systems phase shift, delay or otherwise store a representation of the alternating current fundamental and harmonics, and substantially purge such alternating current fundamental and harmonics from the arc signatures with the stored representation of such alternating current fundamental and harmonics, while substantially preserving chaotic arc signature components. Electric arcs are then monitored from such purged arc signatures. Imperfections in such purging are detected and corrected for a provision of detectable arc signature components free of fundamentals and harmonics that could cause malfunction and false alarms.

Abstract: A power line testing device with signal generator and signal detector incorporates a DC power supply that is capable of generating DC power from a miswired outlet, as long as there is a hot conductor and a return path. The device includes a signal generator which generates a signal that is easily distinguishable from noise. The transmitter further includes a spark gap for creating an arc used to test the function of an ACFI device connected to the branch under test. The transmitter further detects the integrity of circuit ground by measuring its impedance. A receiver of the device measures the elapsed time of the testing signals, permitting a more sophisticated test of interrupter device function.

Abstract: The power supply of equipment being tested for common mode noise problems is connected to a source of power with the power and neutral input terminals of the power supply isolated from the power ground. Recorded common mode noise signals are then inserted between the power supply's neutral input terminal and power ground to produce problem conditions. When the cause of the problem conditions are identified, steps are taken to eliminate the condition.

Abstract: The current and voltage in an electrical system are monitored to detect an occurrence of an arc. The location of the arc is determined by propagating a pulse signal on the system in response to detection of the arc and timing the interval between reception of a portion of the signal reflected back from the location of the arc.