Abstract: A method and apparatus (12-20, 32) for automatically locating faults in a network of signal carriers (cables) utilises an interrogation waveform which is pulse-like in form and receives composite reflected signals from the carriers which are a time distributed collection of individual reflections. These are sampled and compared using the function of an adaptive filter (52) to minimise the difference signal. The difference signals are analysed to determine significant points of departure which identify the fault location which is then represented as a distance value.

Abstract: An arc fault detector for detecting an arc fault in electric power lines includes a two stage arc sensor. The first stage is a current transformer designed for high sensitivity to arc faults but which may saturate and lose detection capability during arc currents at 75A and higher. The second arc fault sensor, which does not saturate, stage senses the voltage across the impedance of the primary of the current transformer, or senses the voltage across the resistance of a section of the load carrying bus which forms the connection through the detector device, or of both, during an arc fault.

Abstract: An arc fault detector for detecting electric power lines includes a sensor for sensing the derivative of the current on the electric power line, a converter circuit for converting the derivative of the line current into first and second signals, the first signal responsive to positive step transitions of arc fault current, and the second signal responsive to negative step transitions of arc current, and a temporal detector for signaling the presence of an arc fault when one of the first and second signals follows the other within a predetermined time, or window, and in which a sequence of one of the signals following the other signal occurs in a second predetermined interval of time.

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 1/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: 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: 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: 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: 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 method and apparatus for location of partial discharges in an electric high-voltage apparatus, such as a power transformer, which is arranged in a container filled with an insulating medium is provided. At least three ultrasonic detectors are applied with mutually known positions on the outside of the container and in acoustic contact therewith. The times of arrival of a wavefront arriving at the detectors and originating from a partial discharge are determined, and on the basis of the times of arrival and on the basis of the known mutual positions of the detectors, the direction the partial discharge is determined.

Abstract: With a circular signal receiving antenna unit (4) constituted by combining two pieces of semicircular conductive plates on a plane in a metallic vessel (3) for the gas insulated apparatus, the electromagnetic waves due to the partial discharge can be detected with a high sensitivity for a broad frequency band. The detected signals are measured by a measuring unit (10) via a hermetical seal coaxial terminal (7) and a coaxial cable (8). The antenna portions of the semicircular plates are designed to extend over a large area. Thus, a capacitance with a potential measurement portion can be increased and a potential measurement with high sensitivity can be performed.

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: A method and device for detecting partial discharges in an electrical apparatus placed in a tank filled with oil, wherein the tank wall is provided with at least one drain tap. The device includes a probe mounted on a carrier that is movable through the opened drain tap into the tank. To move the probe into the tank while avoiding leakage of the oil, a sleeve maybe coupled to a flange of the drain tap an the carrier may be moved within the sleeve. The probe may be moved so that it at least coincides with the inner surface of the tank wall, or even further, and then measurements may be performed to detect partial discharges.

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: 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 comprises: 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: Apparatus and process for non-destructively testing a fluid-filled container for leaktightness, the process comprising: (a) subjecting the fluid-filled container to a vacuum or near vacuum environment; (b) utilizing electrical equipment to form an electrical discharge in the vacuum or near vacuum environment sufficient to stimulate spectral light emissions from volatile fluid-filled container contents present in the vacuum or near vacuum environment; (c) detecting the spectral light emissions from the volatile fluid-filled container contents produced in step (b); and (d) evaluating the spectral light emissions detected in step (c) to determine the amount of volatile fluid-filled container contents present in the vacuum or near vacuum environment by comparing: (i) the measured brightness level of the spectral light emissions obtained from step (c), to (ii) a base brightness level obtained by measuring the brightness level of the spectral emissions due to the presence of residual gas or air molecules in the

Abstract: A method and system diagnose and measure partial discharge on-line in a power transmission system. A first wideband directional clamp-on detector detects pulses corresponding to partial discharge transmitted via a transmission line. A second wideband directional detector detects pulses corresponding to partial discharge output from at least one bushing tap of a high voltage device. The first and second pulses are nulled and then added and/or subtracted, and a diagnostic and measurement system analyzes the results to determine whether the high voltage device and/or an external source produces partial discharge, determine the type of discharge, and measure the level of discharge. For analysis of internal partial discharge, external partial discharges are rejected. The diagnostic and measurement system simultaneously analyzes multiple phases of the output of the high voltage device, while the device is energized. A method and system also diagnose and measure partial discharge off-line in a high voltage device.

Abstract: A system for detecting arcing faults in an electrical distribution network having a line conductor carrying an electrical signal between a power source and a load, the system being capable of detecting series arcs, line-to-neutral arcs and line-to-ground arcs. The system includes a sensor coupled to the line conductor for monitoring the electrical signal and generating a sensor signal representing the electrical signal. The system generates an arc-indicative signal in response to the sensor signal having characteristics indicative of an arcing fault. The system can include a testing system in which a test wire is coupled to the sensor simultaneously with the line conductor and a test signal is periodically produced on the test line. The sensor simultaneously monitors the test signal and the electrical signal and produces a sensor signal representing both the test signal and the electrical signal when the test signal is present on the test line.

Abstract: A method for determining switchgear-specific data at contacts in switchgear and/or operation-specific data in a network connected to the switchgear includes detecting a so-called contact follow-through travel at a switching path as an equivalent criterion for an erosion of contacts, particularly for contactor contacts. A resilience change during a shutdown cycle is measured, can be used to determine the erosion and can be converted into a remaining contact life for the contacts. Accurate measurement of the armature movement from a start of the armature movement to a start of contact opening is required for that purpose. Switching states of a switching device and of the electrical network are additionally detected from signals for resilience detection. An apparatus for carrying out the method is also provided.

Abstract: In a high-voltage installation having at metallic encapsulating housing, a cone antenna is provided as a device for transmitting electromagnetic signals. The cone tip antenna facing the inner wall of the encapsulating housing resulting in an optimal coupling characteristic.

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, wherein the frame is substantially supported by the tire, and at least one pin attached to the frame, wherein the at least one pin is adapted to be connected to a voltage generator to create an electric field therein and 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: 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 comprises: 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: A radio frequency (RF) or other form of detector detects discharges of an insulated system which can occur when electrical insulation becomes wet, for subsequent analysis and decision processes. Additionally, for RF detection, a frequency selector can be used to select a “quiet” region of the discharge spectrum before demodulation and further analysis and decision. Finally, redundant sets of such filters avoid the need to continuously reconfigure the detection system.

Abstract: An arcing fault detector band pass filters the ac current in a protected circuit to generate a sensed current signal with pulses having an amplitude related to the step increases in current produced each time an arc is struck. The envelope of this pulse signal is tracked by a first, slow tracking circuit or envelope detector having a first, long time constant and a second, fast tracking circuit having a second, shorter time constant. When the second tracking signal generated by the second tracking circuit falls below a predetermined fraction of the first tracking signal of the first tracking circuit, a charge pulse modulator generates a pulse of a size which is a function of the amplitude of the most recent pulse in the sensed current signal. When a time attenuated accumulation of the charge pulses maintained on an integrating capacitor reaches a preselected level, an output circuit generates an arcing fault indication.

Abstract: An electromagnetic waveform developing in synchronism with a system power supply by a partial discharge of electric equipment such as a power distribution device is received by an antenna 1. From the electromagnetic waveform of measurement frequency included in the received signal, there are extracted a component changing according to the frequency of the system power supply and a component changing at the frequency twice that of the system power supply. The presence or absence of discharge is determined from the magnitude of each of the extracted components, thereby detecting a partial discharge.

Abstract: A device for sensing discharges in a test object (1) with two electric connection conductors (1a, 1b, 1c, 1d), preferably a cable joint, comprises at least one first and one second sensor (2a, 2b) and evaluation equipment (EVU). Each one of the sensors generates and supplies to the evaluation equipment sensor signals in dependence on current pulses through the connection conductors and the direction thereof, the first sensor a first sensor signal (v1) and the second sensor a second sensor signal (v2). The evaluation equipment generates in dependence on received sensor signals an indication signal (IND), indicating a partial discharge in the test object.

Abstract: An electrical isolation device is provided for use in an electrical distribution network having a plurality of branch circuits each defined by line and neutral conductors connected between a power source and a load, the line conductor being electrically connected to one of a plurality of line buses at an electrical distribution panelboard, the neutral conductor being electrically connected to a neutral bus at the electrical distribution panelboard. The isolation device includes a capacitance coupled between the line and neutral conductor of each of the branch circuits and is designed to provide a low impedance path for an arcing fault occurring on the line conductor of the branch circuit. The capacitance is sufficiently large to provide power factor correcting current.

Abstract: To perform a reliable and calibrated measurement of partial discharges, a first calibratable sensor and a second sensor are arranged in a metal enclosure. The first calibrated sensor picks up signal components in the HF (High Frequency) range, and the second non-calibrated sensor picks up signal components in the UHF (Ultra-High Frequency) range. An HF signal component picked up by the first sensor is transmitted to a partial discharge analyzer. The opening time of the gate device is determined by a UHF signal component picked up by the second sensor.

Abstract: A low cost mixed analog digital application specific integrated circuit (ASIC) includes a standard central processing it (CPU) programmed to execute a correlation function for arc detection. Use of a standard CPU is possible because need for digital fourier analysis is eliminated by the ASIC architecture. The SIC includes a power supply configured to be coupled to an AC power line for supplying power to the ASIC components, and further includes a current sensor coupled to a current-carrying conductor for generating a signal representative of current in the conductor. A first analog-to-digital converter (ADC), coupled in series with the current sensor, has its output coupled to a central processing unit (CPU). The CPU supplies a digital-to-analog converter (DAC) with a digital signal representative of a portion of the sensed current. The DAC supplies this signal, in analog form, to a summer, which also receives an output signal from the current sensor.

Abstract: An encapsulated installation, in particular a switching installation for high or medium voltage, includes a plurality of sensors located in an interior of an encapsulation. A central monitoring device is provided for information interchange with the surface acoustic wave sensors. An antenna element of the monitoring device is disposed at the encapsulation and is directed towards the interior. The sensors can be interrogated selectively.

Abstract: A method for space-charge measurement in a coaxial cable comprising an inner conductor (2), a cable screen (3) and an electric insulation (4) between the inner conductor and the cable screen, wherein the cable screen is removed on both sides of a measurement region, an electric voltage pulse is generated by an electric pulse generator (10) and is applied over part of the insulation (4) of the cable within the measurement range, an acoustic signal, in the presence of space charges in the cable insulation, is generated by the voltage pulse in cooperation with the space charges and a possible acoustic signal is recorded by a sound-recording device (8). A grounded annular outer electrode (7) is applied around the measurement region, the sound-recording device is arranged in direct contact with the annular outer electrode, the voltage pulse is applied to the cable screen on both sides of the measurement region and is connected, via the impedance of the cable, to the inner conductor of the cable.

Abstract: A method and an apparatus for monitoring conditions of electric insulation in a live or energized electric system. The invention takes into account the fact that, when the insulation resistance of an electric system is measured under real live conditions, the electric insulation works under voltages and current-leakage conditions which different from those measured in so-called “cold” state. The invention is based on two voltage measurements in one of which the operating conditions of the electric insulation are artificially changed for a known value. Insulation parameters are then calculated by a set of formulas using the results of the two measurements.

Abstract: Statistical methods of partial discharge analysis utilizing histogram similarity measures are provided by quality assessment and condition monitoring methods of evaluating high voltage electrical insulation. The quality assessment method is utilized to evaluate the quality of insulation within the electrical equipment. The condition monitoring method is utilized during normal operation of the equipment to identify degradation in the insulation and to predict catastrophic insulation failures.

Abstract: In a measurement system for electric disturbances in a metalen-capsulated high-voltage switchgear having at least one measurement probe for each phase for decoupling of electromagnetic interference signals, both the interference signals and the useful voltage are scanned by the same measurement probe in each phase, and both are made accessible, separately from one another, at a filter arrangement.

Abstract: A corona discharge detection device comprising an optical sensor for generating an electrical signal in response to the detection of ultraviolet radiation in a prescribed range. The detection device further comprises an alarm unit which is electrically connected to the optical sensor for generating an alarm signal in response to the electrical signal generated by the optical sensor. The detection device may further comprise a directional unit for determining the location of origin of the ultraviolet radiation. The optical sensor is configured to sense ultraviolet radiation in a spectral range of from about 185 nanometers to about 260 nanometers, and of an intensity in the range of about 1 picowatt per square centimeter to about 1 nanowatt per square centimeter.

Abstract: A tester for an arc fault circuit breaker plugs into a socket in the protected branch circuit. An actuator includes a first spring biasing a moveable contact carried by a pivoted contact arm away from a fixed contact and a momentary closer for momentarily closing the contacts. The momentary closer includes a push button and a second spring coupling the push button to the pivoted contact arm to close the contacts when actuated. Closing of the contacts completes a circuit across the branch circuit resulting in a current producing a magnetic repulsion force which blows the contacts open thereby striking an arc. The arc, which should trip the arc fault circuit breaker is visible through a translucent or transparent section of the molded tester housing. A fuse interrupts any overcurrent and a test light verifies initial energization of the protected circuit and operation of the arc fault circuit breaker.

Abstract: A method of initiating and monitoring partial discharges in an insulating medium is disclosed. Apparatus for performing the method is also disclosed. A relatively low frequency time varying exciting waveform is applied to a sample of an insulating medium. A trigger pulse of short duration is superimposed on the exciting waveform to initiate partial discharge activity in the sample. The apparatus includes a trigger pulse generator with a synchronizing circuit which provides a pre trigger signal for an oscilloscope, allowing the resultant partial discharge activity to be monitored.

Abstract: A portable tester plugs into a receptacle in a branch circuit of an electric power distribution system to verify protection against arc faults, line to ground faults and neutral to ground faults provided by a circuit breaker located at a remote load center or by ground fault and, or arc fault interrupters in the receptacle, and also checks for proper wiring. The arc fault detector gates phased back rectified half cycles of the ac power to generate step changes in the instantaneous amplitude of current in the branch circuit which mimic the repetitive striking of an arc. Preferably, only half cycles at least 60 ms apart are gated so that the user can verify the time to trip with a watch and can count the gated half cycles to trip by counting pulses generated by a light emitting diode (LED) in the gating circuit.

Abstract: An electrical isolation device for use in an electrical distribution network having a plurality of branch circuits each defined by line and neutral conductors connected between a power source and a load, the line conductor being electrically connected to one of a plurality of line buses at an electrical distribution panelboard, the neutral conductor being electrically connected to a neutral bus at the electrical distribution panelboard. The isolation device includes a filter coupled between a selected number of line buses and the neutral bus at the panelboard and is designed to provide a low impedance path for an arcing fault occurring on either of the selected number of line buses. In another embodiment, the isolation device is comprised of a filter coupled between the line and neutral conductor of a selected one of the branch circuits and is designed to provide a low impedance path for an arcing fault occurring on the line conductor of the selected branch circuit.

Abstract: A capacitor bushing with a tap for a reduced voltage between its capacitor inserts is monitored with the method. The reduced voltage is supplied to a detection device that monitors the reduced voltage for any change. A change and its time interval from a further change are determined, and an error signal corresponding to the frequency of the change in the reduced voltage is generated. The method may be performed with the disclosed monitoring system.

Abstract: A metalclad switchgear assembly for high or medium voltage, having a cladding, includes at least one sensor arranged in an interior space of the cladding for detecting a condition variable within the cladding, the sensor having an antenna; and a transmitting and receiving antenna directed towards the interior space, the transmitting and receiving antenna serving for performing a wireless information interchange with the sensor, and for simultaneously detecting electromagnetically partial discharges in the interior space.

Abstract: A system and method for detecting leakage of a part, includes a controller for generating a start command, a voltage generating circuit for generating at least one high voltage pulse signal in response to the start command, at least one testing station including first and second probes for placing a non-conductive part therebetween and for applying the at least one high voltage pulse signal to the non-conductive part, and an inductive detector detecting current from one of the first and second probes. The inductive detector generates a detection signal in response to the detection and transmits it to the controller. The controller compares the detection signal with a reference signal and determines any presence of leaks in the non-conductive parts based on the comparison result.

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: An apparatus for detecting an insulation defect in at least one device connected into an electrical power transmission or distribution network and having: leakage current measuring sensors (10) arranged on a ground line (19a, 19b, 19c) of the device; a measurement signal analogue/digital converter (58, 60); and a signal processing unit (14) including a comparison circuit (75) for comparing the measurement signal with a maximum threshold value representative of the maximum value of the leakage current permitted to flow in the ground line (19a, 19b, 19c), to obtain an insulation defect signal. The processing unit (14) includes a discriminator circuit (76) for discriminating, in the insulation defect signal, between a component of a useful signal and a component of a disturbance signal.

Abstract: A testing device for detecting defects in insulation of electrosurgical instruments that includes an implement or wand having a distal end, an electrode for generating a spark adapted to detect a defect in the insulation, and mounting means for removably mounting the electrode to the distal end of the implement. The removable mounting means includes a shank that is received in a socket or bore defined in the distal end of the wand and is engageable with the wand within the socket so the shank can easily be removed from the socket after use. The wand is releasably engageable with the housing by a flexible bracket that extends from the housing. The device may include a pad having a reflective top surface with ridges upon which the surgical instrument to be tested is placed.

Abstract: Prior to beginning a dielectric withstand (leakage current) or insulative impedance test, but after applying the high voltage that will be used in the test, the temporary charging currents resulting from application of the high voltage are measured and analyzed to determine if the test sample is properly connected to the test apparatus. If no charging currents are measured, or if the insulation resistance is too high, then it is determined that the test sample is not properly connected and the test is terminated.

Abstract: A device for sensing electric discharges in a test object with at least two electric connection conductors comprises transducer equipment and evaluation equipment. The transducer equipment comprises at least one transducer for direction-sensitive sensing of current pulses through the connection conductors by sensing a magnetic field, generated by the current pulses, and the polarity thereof. The transducer delivers a transducer signal to the evaluation equipment in dependence on said current pulses and their direction. The evaluation equipment generates, in dependence on received transducer signals, an indicated signal indicating an electric discharge in the test object.

Abstract: The measuring device is intended for a metal-enclosed, gas-insulated high-voltage installation. It contains at least one Rogovski coil (10), which is arranged in an enclosure tube (3), filled with insulating gas, of the metal enclosure and serves to detect the current in a current-carrying conductor (9), led through the enclosed tube (3), and a measuring electrode (11), which surrounds the conductor (9) and serves to detect the voltage of the conductor (9). The current conductor (9) is rigidly connected to a current-conducting cast armature (13) of an insulator (14) fastened to the enclosure tube (3). In the measuring device according to the invention, a defined field geometry is maintained in the interior of the enclosure tube (3) even over long periods and under changing loads. Consequently, the sensors, in particular the voltage sensor containing the measuring electrode (11), can transmit output signals of high measuring accuracy.

Abstract: A charge pump whose charge transfer switches are formed of charge transfer transistors and single pole, double throw (SPDT) switches each of which controls the gate of its corresponding transistor. Each SPDT switch has two throw contacts, one which is connected to the left diffusion of its corresponding charge transfer transistor and the other of which is connected to ground. Thus, the SPDT switch selectively connects the gate of the charge transfer transistor it controls between a diode connection (the first contact) and ground (the second contact). As a result, the charge transfer switches of the present invention are both fully on (when diode-connected) or fully off (when connected to ground).

Abstract: In a method for monitoring of partial discharges in an electric power transformer (1) under normal operating conditions, the magnetic field at a high-voltage bushing (2) on the power transformer is sensed with an inductive sensor (6) comprising at least one coil (6a, 6b) arranged at the bushing, and the electric field at the bushing is sensed with a capacitive sensor (5). The output signals from said sensors are supplied to a signal processing unit (3) in which each one of the output signals is filtered in a separate bandpass filter (101, 102), whereupon the filtered output signals from said sensors are multiplied by each other. An output signal (PDI) from the signal processing unit is formed in dependence on the result of said multiplication for the purpose of detecting internal partial discharges in the transformer.

Abstract: A microwave sensor includes a case 1 of an object apparatus in which a discharge may occur; the object apparatus 2; an antenna 3 which is attached to the object apparatus case 1 and receives a microwave signal generated by a discharge; a signal processing unit 4 which is connected to the antenna 3, amplifies and detects the microwave signal, mixes the microwave signal with an oscillating signal, converts the mixed signal to a video signal, and amplifies the video signal; and an output terminal 13 through which the video signal is output.