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Showing papers on "Partial discharge published in 1986"


Journal ArticleDOI
TL;DR: In this article, a computer-aided measurement system has enabled novel interpretation of partial discharge (PD) signals, and the authors take into consideration voltage phase-angle at which each PD pulse takes place, and consequently need simultaneous measurement of the pulse height q and the phase angle?.
Abstract: A computer-aided measurement system has enabled novel interpretation of partial discharge (PD) signals. We take into consideration voltage phase-angle at which each PD pulse takes place, and consequently need simultaneous measurement of the pulse height q and the phase angle ?. According to the analysis of PD pulse signals, close relation between PD pulse signals and insulation degradation or defects was found. New PD characteristics such as 4-q distribution profile (average pulse height versus phase angle) can detect the growth of electrical trees in insulation caused by PDs. The skewness of the ?-q distribution was found to be a good measure for insulation degradation by PDs and for electrical trees. The skewness of the ? -q distribution was found to be an indicator of the shape of a void in which PDs occur. A skewness plane or an S-plane is proposed to monitor electrical treeing degradation. Furthermore, an effective noise reduction system is devised for practical b application of the new profile for insulation diagnostics.

114 citations


Journal ArticleDOI
TL;DR: In this paper, the dielectric conditions of converter transformers and smoothing reactors are examined and two additional tests are recommended for this equipment -a long term dc applied potential test and a polarity reversal test.
Abstract: The dielectric conditions which are unique to converter transformers and smoothing reactors are examined. Both steady state and transient situations are discussed. Two additional tests are recommended for this equipment - a long term dc applied potential test and a polarity reversal test. Formulae are developed to calculate proposed test levels, and guidelines are presented concerning allowable partial discharge levels during the tests.

39 citations


Journal ArticleDOI
TL;DR: In this article, the authors characterize the nature of discharge and noise pulses when using capacitive couplers mounted on each phase leads and an RF current transformer mounted on the neutral lead for signal detection.
Abstract: Changes with time in the partial discharge (PD) activity originating in a generator stator's insulation system provide information about the electrical integrity of the stator winding. It is desirable to measure PD during normal service to minimize costs. To do this successfully, the influence of electrical interference must be reduced. Tests are reported which characterize the nature of discharge and noise pulses when using capacitive couplers mounted on each of the phase leads and an RF current transformer mounted on the neutral lead for signal detection. Significant differences between PD and electrical noise have been observed.

32 citations


Patent
Jobst Wolfgang1
19 May 1986
TL;DR: In this article, an air discharge nozzle for ventilating and air conditioning systems and the like is disclosed having directional strips that are disposed pivotably in the discharge jet and are adjustable for directional control of outflow.
Abstract: An air discharge nozzle for ventilating and air conditioning systems and the like is disclosed having directional strips that are disposed pivotably in the discharge jet and are adjustable for directional control of outflow. The arrangement is such that the air can flow through only between any two strips and accordingly, only those partial discharge currents that are oriented by means of the strips are produced.

24 citations


DOI
01 Dec 1986
TL;DR: In this paper, it was shown that fatigue failure due to prolonged vibrational electrostatic forces is the cause of the formation of voids and cracks in polymeric insulation, leading to tree-like structures emanating from protrusions and inhomogeneities.
Abstract: Polymeric insulation suffers from long-term degradation at low alternating stresses, through the development of tree-like structures of discharge channels emanating from protrusions and inhomogeneities. It can take a considerable time, following the application of voltage, before treeing begins. During this time microscopic voids and cracks form within the dielectric providing the necessary partial discharge activity for treeing to commence. The process leading to the formation of voids and cracks under the influence of low alternating fields has generally been thought to be electronic in nature. The work described in the paper demonstrates that this is not so, and that fatigue failure due to prolonged vibrational electrostatic forces is the cause.

22 citations


Journal ArticleDOI
TL;DR: In this article, the main properties of a newly developed impregnant ant for high voltage power capacitors are given, where a new liquid, a mono dibenzyltoluene blend (M/DBT), has a very high degree of aromaticity.
Abstract: The main properties of a newly developed impregnant ant for high voltage power capacitors are given. This new liquid, a mono dibenzyltoluene blend (M/DBT), has a very high degree of aromaticity. The results of many tests carried out both on model and large capacitors are reported. A screening test using a transparent micro-model of an all-film capacitor has been used to study the properties of the fluid when submitted to very high electrical stresses resulting from transient overvoltages at low temperature. re. The correlation between the results obtained with micro-models and with real capacitors are reported. Partial discharge extinction ability of M/DBT is compared to that of liquids being used at present for this application. The authors describe the laboratory test that they have developed to evaluate the performances of the polypropylene filmliquid iquid insulation at high temperature. Using this test, the influence of many parameters is studied. They cast new light on all-film capacitor technology.

18 citations


Journal ArticleDOI
Y. Kamata1
TL;DR: In this article, diagnostic methods for power transforme. r insulation, gas analysis in oil and partial discharge measurements become useful methods, Typical methods are described in this chapter. And they are discussed in detail.
Abstract: Concerning diagnostic methods for power transforme. r ins-ulation , gas analysis in oil and partial discharge measurements become useful methods, Typical methods are described in this chapter.

15 citations


Journal ArticleDOI
01 Aug 1986
TL;DR: In this paper, the application of signal processing techniques in the interpretation of partial discharge (PD) pulses as detected at the terminals of power transformers is discussed, and a description is given of experimental techniques using conventional discharge detectors and a computer-based measurement system.
Abstract: The paper discusses the application of signal processing techniques in the interpretation of partial discharge (PD) pulses as detected at the terminals of power transformers. Special consideration is given to the concept of PD energy and to the effect of waveshapes. Examples are included of FFT analyses of PD waves as stored in digitized transient recorders during HV tests. The possible relevance of the frequency spectra in the assessment of dielectric damage is considered, together with associated circuit effects. A predominant factor in transformer testing is still the need for satisfactory PD location methods: a description is given of experimental techniques using conventional discharge detectors and a computer-based measurement system.

13 citations


Journal ArticleDOI
TL;DR: In this paper, a technique for relating measurable electrical quantities with energies dissipated inside a void in highly electrically stressed insulation is presented, based on measuring, for each apparent discharge level qe, the algebraic sum of the external energy pulses of all discharges having a value qe and occurring over some cycles of test voltage.
Abstract: A technique for relating measurable electrical quantities with energies dissipated inside a void in highly electrically stressed insulation is presented. It is based on measuring, for each apparent discharge level qe, the algebraic sum of the external energy pulses of all discharges having a value qe and occurring over some cycles of test voltage. Theoretical investigations show that the results of such external energy summations are equal to the energies dissipated in the void. A novel histogram is also suggested which relates the apparent discharge amplitudes with their respective energies in the void. Experimental tests were carried out under controlled conditions with samples of thermoplastic and thermosetting dielectric materials. By means of a digital computer-driven instrument, built in our laboratory, good agreement between theoretical and experimental investigations has been found. Work is in progress to extend the application area of the above measurements to complex insulating components.

13 citations


Patent
05 Mar 1986
TL;DR: In this paper, an apparatus and method for the deposition of uniform high energy in a high pressure gaseous medium using an electrical discharge which is suitable for providing a population inversion therein with the consequent support of laser oscillation or amplification is presented.
Abstract: An apparatus and method for the deposition of uniform high-energy in a high pressure gaseous medium using an electrical discharge which is suitable for providing a population inversion therein with the consequent support of laser oscillation or amplification. The electric discharge is achieved without the use of a fast high-voltage, high current switch which must carry the entire discharge current, and requires lower discharge voltages than are normally used for such discharges. The high-energy, high-voltage discharge is initiated and controlled by a low-energy, high-voltage discharge which is in turn initiated and controlled by a yet lower energy preionization pulse which may derive from an electrical discharge or ionizing radiation. The simplicity of the present design permits the construction of rugged, reliable and inexpensive high-power gas lasers.

11 citations


01 Jan 1986
TL;DR: In this paper, a method for the detection and localization of small partial discharges (less than 1 pC) in high voltage cables has been developed, and a number of test cables have been aged during six months at a stress of 15 kV/mm rms at the conductor.
Abstract: This report describes a search for a possible relationship between partial discharges and electrical aging of XLPE cable insulation. It is well known that partial discharges can deteriorate polymeric insulating materials. Recently several theories on the relationship between partial discharges and aging have been published. In order to explore this relationship by experiments a method for the detection and localization of small partial discharges (less than 1 pC) in high voltage cables has been developed. A number of test cables has been aged during six months at a stress of 15 kV/mm rms at the conductor; three cables were held at room temperature and three cables were heated to 9ifc conductor temperature. The following measurements were carried out: partial discharge measurements, tan 0 measurements, breakdown voltage measurements and measurements on physical and chemical properties. The results show no significant aging and therefore no correlation between aging and partial discharge activity could be established. Wolzak, G.G., A.M.F.J. van de Laar and E.F. Steennis PARTIAL DISCHARGES AND THE ELECTRICAL AGING OF XLPE CABLE INSULATION. Department of Electrical Engineering, Eindhoven University of Technology, 1986. EUT Report 86-E-160 Addresses of the authors Dr.ir. G.G. Wolzak High-Voltage Laboratory Department of Electrical Engineering Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands Ir. A.M.F.J. van de Laar Research and Development Department NKF Kabel B.V. P.O. Box 26 2600 MC Delft The Netherlands Ir. E.F. Steennis Electrical Research Department N.V. KEMA P.O. Box 9035 6800 ET Arnhem The Netherlands

Journal ArticleDOI
TL;DR: In this paper, the effectiveness of indicators of discharge intensity has been checked while maintaining "similar conditions" at all discharging cavities belonging to a set of insulation arrangements, each arrangement consists of solid insulation with one air-filled cavity, and its value is used to verify the fact that similar conditions exist in the cavity.
Abstract: The results of measurements of internal partial discharge intensity generally are used to assess the risk of failure of electrical insulation due to internal discharges. However, with the use of present definitions ions of discharge intensity, there is as yet quatenadeuate information for specifying acceptable levels of intensity. The effectiveness of indicators of discharge intensity has been checked while maintaining "similar conditions" at all discharging cavities belonging to a set of insulation arrangements. Each arrangement consists of solid insulation with one air-filled cavity. A new, nonmeasurable quantity, the average discharge current transferred across the discharging cavity, has been introduced and its value is used to verify the fact that similar conditions exist in the cavity. Furthermore, a new and more accurate pattern of recurrence of discharges has been used to identify four groups of discharges, which in turn leads to a new definition of discharge intensity. The results of computations of theoretical values of the new and presently used indicators are presented and the advantages associated with use of the new definition are explained.

Proceedings ArticleDOI
01 Nov 1986
TL;DR: In this paper, the authors present data on electrical breakdown strength and partial discharge inception voltage of polypropylene film oil-immersed under a.c., d.c. and superimposed a., upon d.C. voltages, conditions that may exist in HVDC converter stations equipment.
Abstract: The paper presents data on electrical breakdown strength and partial discharge inception voltage of polypropylene film oil-immersed under a.c., d.c., and superimposed a.c., upon d.c. voltages, conditions that may exist in HVDC converter stations equipment. In the latter case the ratio of the a.c. to d.c. voltage components (p = V a.c. /V d.c. ) was varied between the limits of 0.2 ≤ d ≤ 10. The results obtained under combined a.c. plus d.c. voltages follow closely an expression which relates the breakdown voltage to the sum of arc tangent and arc cotangent function of the parameter p. The partial discharge inception voltage remained independant of the parameter p.


Journal ArticleDOI
TL;DR: In this paper, a description of composite insulation, including swelling of polymers by oil, oil streaming electrification of solid dielectrics, and V-t characteristics of LN2-impregnated insulation due to partial discharge is given.
Abstract: A description is given of composite insulation, i. e. swelling of polymers by oil, oil streaming electrification of solid dielectrics , and V-t characteristics of LN2-impregnated insulation due to partial discharge. Swelling can be accelerated by ultrasonic wave irradiation. This reduces the saturation time. Polypropy-lene-laminated paper would swell less inside its cable structure. Ac dielectric breakdown strength increases with swelling in the early stage and then decreases. Streaming electrification was found to be influenced by the oil flow rate, temperature, ac applied voltage, and the type of solid and liquid dielectrics. Surface roughness of solid dielectrics does affect the electrification greatly. Addition of benzotriazol at only ppm is effective in suppressing the electrification. V-t characteristics are divided into two regions for liquid nitrogen (LN2) impregnated insulation. The value of n in Vnt= const ranges from 50 to 100 in the first region, while it is around 5 to 10 in the second region.

Patent
25 Sep 1986
TL;DR: In this paper, a discharge electrode is provided for the purpose of forming gas ions and having a high electrical voltage compared with a counter-electrode, in order to ensure a discharge current at atmospheric pressures in the range of the Townsend discharge or glow discharge, with an aperture angle of less than 180 degrees of the imaginary spherical sectors around the emission points of the discharge electrode.
Abstract: of EP00294211. Device for generating a directed current of a gaseous medium, utilizing the electric wind, a discharge electrode 1 being provided for the purpose of forming gas ions and having a high electrical voltage compared with a counter-electrode 3, in order to ensure a discharge current at atmospheric pressures in the range of the Townsend discharge or glow discharge, so that the ions move in a preselected direction 5 or in a preselected sector, with an aperture angle of less than 180 degrees of the imaginary spherical sectors around the emission points of the discharge electrode 1, characterised by the fact that the discharge electrode 1 takes the form of a wire, that corresponding to each discharge electrode there are at least two mutually parallel counter-electrodes 3 present to one side of the discharge electrode and at an equal distance from the latter, the nearest edge of each one extending parallel to the wire-shaped discharge electrode 1, and that the discharge current is between 10**-6 A/cm**2 and 10**-1 A/cm**2 .

Journal ArticleDOI
TL;DR: In this article, the authors made a study of the mechanisms of formation of a self-sustained volume discharge in CO2-N2-He gas mixtures initiated by an auxiliary barrier discharge distributed on the surface of a cathode.
Abstract: A study was made of the mechanisms of formation of a self-sustained volume discharge in CO2–N2–He gas mixtures initiated by an auxiliary barrier discharge distributed on the surface of a cathode. The volume discharge was initiated when the discharge gap was filled by an electron flux formed from the barrier discharge plasma in the course of a smooth rise of the voltage across the electrodes. Measurements were made of the small-signal gain confirming the model of formation of a self-sustained volume discharge and demonstrating that a discharge of this kind could be used to amplify nanosecond light pulses.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the circuit equation can be solved approximately for a suitable variation of the resistance with time, and the results were compared with experimental results and with a numerical solution for the case of electrical discharge through commercial steel powder.

Patent
30 Jun 1986
TL;DR: In this paper, the authors proposed a method to detect the generation of a partial discharge accurately without being affected by nose ultrasonic waves, by inputting an ultrasonic wave generated at a power cable connection into the ultrasonic detection sensor being propagated through a phone.
Abstract: PURPOSE: To detect the generation of a partial discharge accurately without being affected by nose ultrasonic waves, by inputting an ultrasonic wave generated at a power cable connection into an ultrasonic detection sensor being propagated through a phone. CONSTITUTION: As an AC voltage at the commercial frequency of 50Hz is applied to a power cable, a partial discharge (a) is caused within a connection 1 100 times per sec. Therefore, an ultrasonic wave due to the partial discharge is also generated 100 tomes per sec. and an ultrasonic wave detecting sensor 3 outputs a discharge detection signal at 100Hz. When a low-frequency signal comprising a band portion (at 100Hz) near the peak value of the discharge detection signal and a noise signal is inputted into a phase detection circuit 9 for taking out a specified phase alone, a band component near the peak value of the discharge detection signal alone is outputted from the phase detection circuit 9 with the noise signal removed. COPYRIGHT: (C)1988,JPO&Japio

Patent
17 Mar 1986
TL;DR: In this paper, the authors proposed to enable accurate and efficient testing of partial discharge with a reduction in the measuring time, by providing charge segmentation circuits and counting circuits equivalent to the number of steps of charge segment values to perform a specified computation for discrete values.
Abstract: PURPOSE:To enable accurate and efficient testing of partial discharge with a reduction in the measuring time, by providing charge segmentation circuits and counting circuits equivalent to the number of steps of charge segment values to perform a specified computation for discrete values. CONSTITUTION:Pulses only in the size exceeding the charge segment values are extracted from discharge pulses which are detected with an input circuit 5 and passed through an amplification circuit 6 with discharge segmentation circuits 11 which are arranged equivalent to the number of steps of charge segment values and have thresholds corresponding to the charge segment values. Then, the discharge pulses exceeding the respective charge segment values are counted with counting circuit 12 provided corresponding to the respective circuits 11. The individual descrete values thus obtained are memorized temporarily into a memory computation circuit 13 and the difference of the descrete values between the adjacent discharge segment values is computed to determine cumulative frequencies of pulse generations for each segment value, which is shown on a display 14 in terms of the segment value.

Proceedings ArticleDOI
01 Nov 1986
TL;DR: An internal discharge pulse measurement system which could analyze the distribution of the discharge according to each phase area of the applied voltage (AC 50Hz) was developed in this paper, where a half cycle of applied voltage starting from the negative peak and ending at the positive peak was divided into nine equal phase areas.
Abstract: The purpose of this research was to predict breakdown of electrical equipment due to deterioration of insulation. An internal discharge pulse measurement system which could analyze the distribution of the discharge according to each phase area of the applied voltage (AC 50Hz) was developed. The system's features were as follows. A half cycle of the applied voltage starting from the negative peak and ending at the positive peak was divided into nine equal phase areas. The distribution of the discharge in each phase area was expressed with a three dimensional displaying method whose dimensions were discharge magnitude (q), number of pulses (n), and time (t).

Patent
20 Jan 1986
TL;DR: In this paper, the authors detect internal partial discharge with high sensitivity by connecting a core and a core clamping device as grounding structures as the contents of a transformer to a grounded tank by grounding wires and mounting an impedance element or current transformer to the grounding wires.
Abstract: PURPOSE:To detect internal partial discharge with high sensitivity by connecting a core and a core clamping device as grounding structures as the contents of a transformer to a grounded tank by grounding wires and mounting an impedance element or a current transformer to the grounding wires. CONSTITUTION:Partial discharge generated in a tank 7 is produced among a winding 5 as a high-voltage charging section and grounding structures, but core clamping devices, such as a core 1 or a patch 2, a clamp 3, etc. are positioned where nearer to the winding 5 than the tank 7 as the grounding structures, and the probability of partial discharge generated among these core clamping devices and the winding 5 is higher than partial discharge generated in the tank 7. When partial discharge is generated among these grounding structures and the winding 5, all of discharge currents at high frequency based on partial discharge pass through grounding wires 8a, 8b and flow through the tank 7 because charges flow into the grounding structures and the potential of the grounding structures is floated from the tank 7 by an insulating sheet 6. A voltage drop generated by the discharge currents is produced at both ends of an impedance element 9, the voltage is measured by a lead wire 11, and internal partial discharge can be detected.

Patent
04 Aug 1986
TL;DR: In this paper, a delay circuit, change-over circuit, and discriminating circuit is proposed to detect partial discharge pulses of corona and void corona in gaseous SF6 in the form approximate to the original waveform.
Abstract: PURPOSE:To make possible the detection of the partial discharge pulses of corona, void corona, etc. in gaseous SF6 discriminatively from an incoming noise by providing a delay circuit, change-over circuit and discriminating circuit, etc. CONSTITUTION:This device detects both partial discharge pulses of the corona and void corona in the gaseous SF6 in the form approximate to the original waveform and can change over the delay time of phase shifting subtractor circuits 31, 41 to two delay time regions 2-4nS and 10-30nS. The device removes the incoming noise having the pulses longer than the respective two delay time regions and makes use of the difference in the pulse width between the above-mentioned corona pulse and void corona pulse so that only the corona in the gaseous SF6 can be detected in the stage of changing over 2-4nS and that the corona and void corona are detected in the stage of changing over 10-30nS. The partial discharge pulse detected only in the stage of the change over in the delay time region of 10-30nS is discriminated as the void corona and the partial discharge pulses detected in both delay time regions of 2-4nS and 10-30nS are discriminated as the corona and the alarm signal corresponding to the kind of the partial discharge is emitted in the discriminating circuit 70.

Journal ArticleDOI
TL;DR: In this paper, a Versuchseinrichtung beschrieben, with the TE-Kenngrößen, wie scheinbare Ladungsmenge, TE-Häufigkeit, die TE-Energie, the Polarität and the Phasenlage, zur anliegenden Wechselspannung über einen längeren Zeitraum automatisch erfaßt and registriert werden können.
Abstract: Es wird eine Versuchseinrichtung beschrieben, mit der Teilentladungs{TE)-Kenngrößen, wie die scheinbare Ladungsmenge, die TE-Häufigkeit, die TE-Energie, die Polarität und die Phasenlage, zur anliegenden Wechselspannung über einen längeren Zeitraum automatisch erfaßt und registriert werden können. Das Meßsystem gliedert sich in drei Teilbereiche: einen Hochspannungsaufbau in einer geschirmten Meßkabine, einen Analogteil zur Aufbereitung des TE-Impulses und einen Digitalbereich mit Zwischenspeicher sowie angeschlossenem Mikrocomputer und Matrixdrucker /Plotter. Nach einer detaillierten Beschreibung der Signalverarbeitung werden Ergebnisse orientierender Messungen an gefülltem Epoxidharz mit solchen an Polyethylen verglichen.

Patent
16 Jun 1986
TL;DR: In this article, a high speed analogue signal processing circuit for generating an output signal by judging that partial discharge was generated in the mark section corresponding to a section pulse and a display circuit for displaying a location section.
Abstract: PURPOSE:To enhance accuracy, by providing a high speed analogue signal processing circuit for generating an output signal by judging that partial discharge was generated in the mark section corresponding to a section pulse and a display circuit for displaying a location section. CONSTITUTION:Operation circuits, for example, multiplier circuits 41-44 are respectively provided to a location apparatus corresponding to pulse generation circuits 31-34 and, only to multiplier circuits 41-44 to which the respective output section pulses of the pulse generation circuits 31-34 and the output propagation wave line of a partial discharge measuring device 11 were inputted as input signals, the output propagation waves amplified by multiplying the section pulses are outputted. Position display circuits 51-55 are also provided to the location apparatus corresponding to the multiplier circuits 41-44 and triggered by the output propagation waves and the position display circuit corresponding to a location section where partial discharge was generated can lights or issue alarm sound to make it possible to know the location section. By this method, a min. locating distance can be shortened by almost one figure and accuracy can be enhanced.

Proceedings ArticleDOI
01 Nov 1986
TL;DR: In this paper, it is shown that variations in the voltage used during testing can be a useful parameter in extending the usefulness of both pulse height analysis (PHA) and pulse phase angle analysis (POA).
Abstract: Many experiments have been aimed at finding a relationship between partial discharge spectra (1),(2) and insulation condition, but a clear consensus has not yet been formed. The work described is part of a larger effort designed to learn more about the relationships between the life of machine insulation and diagnostic indices derived from corona spectroscopy and other measurements. In particular, it is shown that variations in the voltage used during testing can be a useful parameter in extending the usefulness of both pulse height analysis (PHA) and pulse phase angle analysis (POA).

Patent
20 Mar 1986
TL;DR: In this paper, the authors presented a method to accurately detect an electromagnetic wave generated by partial discharge using an AM receiver, by subjecting the signal, which is received by limiting the receiving band of the partial discharge of electric machinery to a predetermined range, to AM detection to convert the same to sound signal to detect partial discharge.
Abstract: PURPOSE: To accurately detect an electromagnetic wave generated by partial discharge using an AM receiver, by subjecting the signal, which is received by limiting the receiving band of an electromagnetic wave generated by the partial discharge of electric machinery to a predetermined range, to AM detection to convert the same to a sound signal to detect partial discharge. CONSTITUTION: A receiving band is set to a range of 1W60MHz. The position of the antenna 5 in a metal container 1 is set to frequency, wherein the intensity of the foreign radio wave emitted toward the antenna 5 from an external circuit through a main circuit conductor part 2 attenuates to -20db until reaches to the position of the antenna 5 from a conductor, or less. The output of the antenna 5 receiving an electromagnetic wave is inputted to a mixer 7 through a high frequency amplifier 5 to perform heterodyne detection and an intermediate frequency signal is outputted. This signal is detected by an AM detector 1 through an intermediate frequency amplifier 10 and inputted to a speaker 13 through a low frequency amplifier 12 to be converted to a sound signal to detect partial discharge. COPYRIGHT: (C)1987,JPO&Japio

Patent
18 Dec 1986
TL;DR: In this article, the authors measured insulation deterioration with high accuracy by simultaneously measuring DC leak current, position where partial discharge is generated and the change quantity of partial discharge and removing the influence of the discharge and external noise on the result of measurement.
Abstract: PURPOSE:To measure insulation deterioration with high accuracy by simultaneously measuring DC leak current, position where partial discharge is generated and the change quantity of partial discharge and removing the influence of the discharge and external noise on the result of measurement. CONSTITUTION:Sensors 30 and 40 are provided to the measuring end and remote end of a cable 20 to be measured. The sensor 40 is connected via a guard return cable 60 to an electric power source 50. The output of a monitor 81 is recorded via filter 91 in a measuring unit 90. the pulse wave induced by partial discharge is propagated toward both of the measuring end and remote end of the cable 20 if the partial discharge is generated at the deteriorated insulation part P of the cable 20 by the impression of a high voltage thereto. The pulse wave arriving at the measuring end of the cable 20 passes the impedance of the sensor 30. The light signal indicating the pulse wave is inputted via an optical fiber 72 to a monitor 82. The power source 50 and units 90, 100 and 110 are integrally controlled by a microcomputer 140 for system control. The influence of corona discharge is therefore not received.

Journal ArticleDOI
TL;DR: In this article, a simple model of DC partial discharges running in cable and capacitor dielectrics is described in order to investigate the influence of the measuring circuit on the DC partial-discharge repetition rate.
Abstract: A simple model of DC partial discharges running in cable and capacitor dielectrics is described in order to investigate the influence of the measuring circuit on the DC partial-discharge repetition rate. This model shows that the measuring circuit can only influence the discharge repetition rate temporarily. On reaching the stationary state the DC partial discharges are governed by the electric qualities of the dielectric used.

Patent
20 Oct 1986
TL;DR: In this article, a flyback transformer is used to charge the low-voltage transformer to a specified high voltage to measure the partial discharge of the flyback transform, in which a partial-discharge detector (D) is decoupled from a measuring impedance (Zm) connected in series to the high voltage winding of the transformer.
Abstract: For measuring the partial discharge, the low-voltage winding (NW) of a flyback transformer (T) to be tested is excited with flyback pulses for a short time in order to charge the transformer (T) to the specified high voltage. During the charging process, a partial-discharge detector (D) is decoupled from a measuring impedance (Zm) connected in series to the high-voltage winding (HW) of the transformer (T). The partial discharge is measured during the direct-voltage state existing after the charging process, in which state the coupling between measuring impedance (Zm) and partial-discharge detector (D) is restored. To calibrate the partial-discharge measuring device by means of a calibration pulse of known charge quantity, diodes (D1...Dn) connected into the high-voltage winding and moulded together with the transformer are biased in the forward direction.