11th International Symposium on High-Voltage Engineering (ISH 99)
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- Location: London, UK
- Conference date: 23-27 Aug. 1999
- ISBN: 0 85296 719 5
- Conference number: CP467
- The conference proceedings are published in five volumes. Volume one deals with measurements and test techniques; EMC sources, tests, protection; Volume two deals with fields: calculation and measurement; lightning, protection against strikes, earthing; Volume three deals with gaseous, vacuum and liquid dielectrics; Volume four deals with insulators and materials; and Volume five deals with dielectric diagnostics, expert systems; industrial applications
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Quality of high-voltage research and testing
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v1:1
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High-voltage research, which is usually directed at equipment for service, has to take into account the final aim of satisfactory performance in the power system. The adoption of a test standard for research is not sufficient, if it is not proven that the simplifications made to convert the system stresses into test conditions are also valid for the research objective. High-voltage testing is, in most areas, well specified by standards. Its quality, therefore, is guaranteed, if the requirements in these standards are correctly observed. Contrary to the field of research quality, therefore, testing quality is matter of quality management and only this area is addressed by the relevant standards. (4 pages)
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Continuous monitoring of circuit-breakers using vibration analysis
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v1:102
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This paper describes a prototype instrumentation for continuous monitoring of circuit-breakers using vibration analysis. A PC-based equipment records vibration patterns, performs analysis and presents trends automatically. Some preliminary results are presented, and the experience with the method and instrumentation is briefly outlined. The results so far are sufficiently interesting to continue pursuing the technique. (5 pages)
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Relative risks of end arm discharges on stator bars
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v1:107
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Long term aging tests of stator bar end arms were carried out over two years. Six specimens affected by one of three types of defects were studied. The defects were corona activity around the junction of the armor and the end arm stress grading system, surface tracking and bar-to-bar discharges. All the specimens were submitted to an aging voltage of 20 kV AC (2.5*U0). Phase resolved partial discharge (PRPD) and spectral analyses were performed periodically, to characterize each type of activity. After more than two years of aging, the authors noted that some types of activities were very sporadic, while others were more permanent. Three failures occurred up to now, two of them after less than 240 days of aging on specimens with corona activity at the junction. The third failure occurred on a specimen affected by bar-to-bar discharges after 680 days. Despite the fact that all failures occurred in the straight portion of the bars, the authors believe that the corona activity was, at least partially, involved in the failure mechanism on each setup. (5 pages)
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Experimental studies of influence of load capacitance on the output voltage of the impulse voltage generatore
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v1:112
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The amplitude, waveform and efficiency are the main factors to evaluate the overall performances of an impulse voltage generator (IVG), especially, under larger load capacitance such as capacitive potential transformer, or with larger test circuit sizes like the testing of EHV equipment. Analysis and experimental studies show that, to the given main capacitance of IVG, the front time would increase to exceed the required range specified by IEC standards under lightning impulses; while the efficiency of the IVG decreases. For switching impulses, the influence of the test circuit parameters, such as series resistance and load capacitance, on the efficiency of the IVG is also investigated. The results show that there exist a set of optimum parameters which not only make the time parameters within the specified limits, but also result in higher efficiency. (4 pages)
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Testing method and statistical analysis applied in lightning impulse critical flashover
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v1:116
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This paper presents software designed to deal statistically with the common lightning and switching testing results. The objective of the “Testing Method and Statistical Analysis” software is to make possible the fast analysis of the results of an impulse testing sequence, usually considering an amount of impulses per series much larger than the common practice. This software was designed to allow the automatic generation of reports, which makes the analysis of the results easy. It has the option of printing a complete report, recording of each test sequence results, setting up a complete historical data of the experiment with all the possible and available information, allowing the modification of any data to any moment, avoiding errors. By computing the critical flashover voltage, standard deviation paths and also the likelihood surface form, some analyses regarding the test execution can be performed. (4 pages)
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Performance tests on impulse measuring systems at ultra high voltage research laboratory
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v1:120
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The paper presents procedures adopted for the calibration of measuring systems to ensure their use in impulse tests. Different tests were conducted on the measuring systems for qualifying the testing laboratory as possessing Approved Measuring System (AMS) for recognition of the formal competence to perform certain HV tests. In the absence of the Reference Measuring System (RMS), wherein both dynamic response and scale factors are determined together, alternative methods as proposed in IEC 60-2 were used for qualifying the measuring system as Approved Measuring System, the results of which are presented in the paper. The results of pulse calibration of digital recorders are also presented in this paper to establish the test facility to perform tests on equipments in compliance with the international standards. Some of the limitations in the calibration of systems for high voltage measurements are also described. (4 pages)
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Development of HV DC standard in the JEMIC
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v1:124
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As a primary standard the HV divider of 200 kV rating (2 GΩ) made by Vishay Co. has been introduced. Its calibration method has been studied by two methods; resistance measuring method and comparison method with low voltage standard dividers. By using the latter method the calibration of ratios is simplified and the time needed to it is shortened. This method reflected the real state of current flow comparing with resistance method. And also the voltage coefficients and characteristics have been determined. The uncertainties of the standard divider have been estimated as better than 10 ppm (2σ) at 100 kV and 20 ppm (2σ) at 200 kV. (4 pages)
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Compensation of step response “creeping” of a damped capacitor divider for switching impulses
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v1:128
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The subject of “creeping” dividers is still a practical problem in any high-voltage laboratory. This paper describes a procedure that may be used to correct the step response creeping of a damped capacitor divider due to frequency dependence of the high voltage capacitor. This involves several steps, starting from the initial step response measurement, then, estimation of the values of compensating components, confirmation of the compensated step response using a circuit emulation program, and the final response measurement/component refinement and any necessary iteration. (4 pages)
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Development of national standard class reference divider for impulse voltage measurements
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v1:13
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This paper describes the details of the recently constructed Japan's 500 kV National Standard Class Divider whose unit response parameters are measured to be better than the already developed 700 kV Reference Divider's, which fulfils IEC-60060 requirements. The 500 kV divider has a specially tuned compensating circuit in the low voltage arm, making its unit step response quite close to an ideal. Also in the paper, the tuning technique, which makes the experimental response time almost zero, is discussed. (4 pages)
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Measurement of harmonics with optical sensor systems and investigation of harmonic sources in industrial distribution systems
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v1:132
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In this paper, using optical harmonic measuring instruments for high voltage and the harmonic analyzers, the patterns of the harmonics in the distribution systems in an industrial area were simultaneously measured at the field test location distribution line in the neighborhood of a factory and at the same distributing substation. Carrying out the measurements of harmonics in a communication factory and the method of phase discrimination, the authors have found the harmonic sources in an industrial distribution line. The power factor in an industrial distribution line was measured and evaluated by the distortion factor. (4 pages)
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Design of a novel oil tester calibrator based on capacitive dividing mechanisms
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v1:136
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This paper introduces a novel high voltage (HV) measuring instrument designed to calibrate oil insulation testers. Two parts were included: the calibrator block; and the data processing and display unit. It overcomes the difficulties of measuring high voltage in a small enclosure. The designed instrument can be used for any other HV measurements, especially within small enclosures. (4 pages)
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Application of P and MP algorithms to high voltage digital measurements
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v1:140
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This paper applies the Prony and matrix pencil (P & MP) algorithms to high voltage digital measurements for the first time. In these algorithms, the measured data are fitted by a linear combination of complex exponentials. Therefore they are quite applicable to signal processing in digital measurements of high voltage and other electrical engineering. (4 pages)
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Measurement of very fast transient overvoltages (VFTO) in a GIS module
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v1:144
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Gas insulated substations (GIS) have found a wide range of acceptance in power system for their compactness, high reliability and freedom from periodic maintenance (large mean time between failures). This paper deals with the design and development of a capacitive voltage divider for measuring VFTO, as encountered in GIS. The short response time for the divider is achieved by forming the high voltage arm of the divider in the gas insulated bus-duct itself. Further, the simulation of VFTO has been carried out using Electromagnetic Transient Program (EMTP). The comparison of measured and the simulated VFTO validates, satisfactorily, the performance of the new divider. (4 pages)
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Long-term charging test for 500 kV GIS
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v1:148
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This paper describes the long-term charging test performed before a 500 kV gas-insulated substation (GIS) runs in an electrical system, and some results are presented. It contains the results of measuring tests for partial discharge, very fast transient overvoltage (VFTO) when a disconnector operates and the leakage current of metal oxide arresters. (4 pages)
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A new, high voltage, arbitrary waveform generator for lightning protection research and other applications
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v1:152
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In this paper, the authors describe the main features of a new prototype high-voltage arbitrary waveform generator (HVAWG). This generator was designed to produce a variable, programmable wavefront up to a 200 kV peak voltage. Hence, it is capable of precisely simulating the rapidly escalating electric field due to an approaching lightning downward leader, including the well-known steps or pauses as the leader progresses toward its point of attachment near the ground. It utilises a computer-controlled interface that drives a set of series-stacked flyback transformers. The resulting output is any desired, monotonically increasing waveform, downloaded from the computer. (4 pages)
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Capacitive sensor for the measurement of VFTO in GIS
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v1:156
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A capacitive sensor based on the theory of electric field measurements using floating electrodes has been developed for the measurement of VFTO and the same has been fitted to the metallic enclosure of a 145 kV gas insulated substation (GIS) experimental test setup available in the laboratory. The sensor has been calibrated in situ with sinusoidal, impulse and step voltage excitations of the HV bus of the 145 kV GIS and the results are presented. The sensor was then used to measure the 50 Hz restrike pattern as well as the VFTO waveforms during a simulated disconnector switching operation in the 145 kV GIS test setup. It has been demonstrated that the same sensor is able to faithfully measure both the 50 Hz restrike pattern as well as the ns duration VFTO waveforms successfully. (4 pages)
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A new current measurements system using an azimuth angle modulation method
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v1:160
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With advancing opto-electronic techniques, current sensors which consist of a Faraday crystal have attracted much interest in measuring currents which flow at high potentials, such as UHV (ultra-high-voltage) transmission lines, because the Faraday crystal is a kind of insulator having an optical transparency for laser beams. When the current sensor is connected to a long fiber cable, it is very hard to accurately hold current information due to birefringence in the optical fiber, even if the polarized plane is preserved in the cable. From this point of view, the authors have developed a new current measuring system using an azimuth angle modulation method. From a series of experiments, it is found that the present current measuring system is useful for precisely and accurately measuring not only AC, but also DC current flowing at high potentials. (4 pages)
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A new wirewound resistive divider for steep front impulse tests: design criteria and calibration procedure
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v1:164
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This paper summarizes the work done on the design of a new voltage divider used for steep front and/or puncture tests on insulator units. Moreover, the paper reports the tests performed for its qualification, the results obtained and a proposal of calculation of scale factor uncertainty. (4 pages)
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Frequency characteristics method development
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v1:168
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The work containing the application investigation results of the Fourier integral transformation for high voltage impulse measuring systems parameters determination was presented. The amplitude frequency spectrum of the inverse Fourier transformation was submitted, low frequency and high borders of the spectrum were investigated. The parameters calculation method of the standard nonperiodic switching voltage impulse was worked out. The development of basic positions and certification methods of the high voltage switching impulses measuring system have been formulated. (4 pages)
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Analysis of errors in the measurement of chopped impulses
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v1:17
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IEC 60-2 with its new approach to the qualification of industrial measuring systems covers also the case of chopped LI (lightning impulses), with time to chopping down to 500 ns. The paper discusses the procedure for the possible qualification of a reference measuring system in terms of the parameters of the USR, the sources of error and their dependence on the actual waveform: the influence of the shape of the voltage collapse depending upon the way in which the chopping action is obtained is also discussed. (4 pages)
