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Volume 114, Issue 1
Displaying 1-20 of 20 articles from this issue
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Masaru Ishii1994 Volume 114 Issue 1 Pages 1
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
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Tatsuo Kawamura1994 Volume 114 Issue 1 Pages 2-5
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
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Tatsuya Harada1994 Volume 114 Issue 1 Pages 6-10
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
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Masashi Yoshimi, Hiroshi Koizumi, Yoshiya Ogihara, Hiroshi Kumekawa1994 Volume 114 Issue 1 Pages 11-18
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
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Masafumi Yashima, Hideo Fujinami, Tadasu Takuma1994 Volume 114 Issue 1 Pages 19-25
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSA reliable technique is needed for accurate measurement of very fast transient overvoltages such as disconnector-induced surges occurring in GIS which have very steep front and high frequency oscillation. Recently, capacitive voltage sensors with very short response times have been proposed for this purpose. How-ever, few studies have been made on the dielectric properties of materials used for a low-voltage-side capacitor, as well as frequency bandwidth of the measuring system.
In the present work, we propose a thin mica plate for a low-voltage-side capacitor which has a surface coated with silver on both sides. This material has been shown to have stable and high static capacitance up to a high frequency range. We also give a quantitative estimate for the frequency bandwidth of the measuring system. Furthermore, we have developed a practical-scale sensor of this type which can successfully measure simulated disconnector-induced surges of several hundred kV under similar conditions in GIS.View full abstractDownload PDF (5139K) -
Tsuguhiro Takahashi, Kunihiko Hidaka, Teruya Kouno1994 Volume 114 Issue 1 Pages 26-32
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSAn optical electric field sensor using Pockels device has the advantages of directly measuring the electric field in space and of hardly disturbing the field distribution by inserting the sensor, and an optical waveguide technique has been introduced to miniaturize the sensor.
The sensor based on Mach-Zehnder interferometer, which was developed first, utilizes an interference between two light beams which propagate in two waveguides. Its configuration is simple, but the sensitivity to an applied electric field is not necessarily high. The second sensor using a single waveguide on a z-cut LiNbO3 crystal utilizes an interference between TE and TM mode which propagate in the waveguide. Its sensitivity to an applied electric field is high, but it has an instability owing to a thermal disturbance.
In the new sensor, a light beam travels along a single z-direction waveguide on a y-cut LiNbO3 crystal. The width of the waveguide is 7 μm and its length is 4.39mm. Its configuration comes to be more simple than previous ones. The sensor has a good linearity of its output to applied electric fields, a good response for AC and impulse electric fields and a robustness to thermal disturbances.View full abstractDownload PDF (1035K) -
Naoyuki Shimomura, Masayoshi Nagata, Hidenori Akiyama1994 Volume 114 Issue 1 Pages 33-37
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSRogowski coils have been used to measure the pulsed or impulse current without cutting off the circuit. Rogowski coils are usually classified into the differentiating and self-integrating types, which are available in comparatively low and high frequency ranges, respectively.
Here, the resonance characteristics of self-integrating Rogowski coils were experimentally observed, and numerically analyzed. A distributed constant circuit was considered to analyze numerically the Rogowski coil. The numerical analyses gave results which agreed with experimental results. It was confirmed that the resonance phenomena, caused the distortion of the waveforms measured by the self-integrating Rogowski coil, occurred in a range of high frequency. The configuration of Rogowski coil influenced its resonance characteris-tics. The resonance frequency increased with decreasing the number of turns and the cross section of the coil and increasing the distance between the coil and the shield. The cut-off frequency of Rogowski coils in the low frequency range was also verified.View full abstractDownload PDF (1269K) -
Hiroji Yokote, Masami Uno1994 Volume 114 Issue 1 Pages 38-44
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSAlready reported method named feedback pulse-lengthener circuit, capable of measuring peak value of narrow impulse is introduced. Negative feedback pulse-lengthener circuit can detect an impulse as narrow as 14 nsec, with linear relationship between voltmeter reading and the peak value of the applied impulse for the limitted range of peak value.
Positive feedback pulse-lengthener circuit can detect an impulse as narrow as 1 nsec. Linear relationship between voltmeter reading and peak value of an impulse holds in this case.
To measure higher peak value of an impulse, a voltage divider will be needed, preattached to the feedback pulse-lengthener circuit.
To detect more narrow impulse, an amplifier or a buffer of higher speed will be needed. An amplifier or a buffer consisting of ultra high frequency discrete elements is preferable to rather than high speed operational amplifier.View full abstractDownload PDF (1188K) -
Toshiaki Ueda, Masao Morita, Tokio Yamagiwa, Masahiro Kan, Takanobu Og ...1994 Volume 114 Issue 1 Pages 45-52
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSIn recent years, improvements in the reliability and quality of the power supply are more desired than ever before. However, the fault caused by lightning ranks still first in the power system below 154 kV, therefore effective prevention of the lightning faults is needed. The governing factor for insulation strength of substation apparatus is lightning impulse voltage, and it is necessary to know the voltage level and distribution in a substation caused by lightning surge, in order to investigate the rational insulation coordination. For this purpose, authors have been measuring lightning surges at two 77 kV conventional type substations since 1990. In this paper, the automatic measuring systems for lightning surges invading into substations are reported, and measuring results are analized statistically.View full abstractDownload PDF (1863K) -
Yoshio Ohashi, Nobuhiro Hirata, Tatsuya Nagata, Junichi Shinagawa, Yas ...1994 Volume 114 Issue 1 Pages 53-59
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSIn order to investigate the transient phenomenon induced by lightning strokes or switching operations, unattended long-term transient current measurements were obtained in a several mannar. One is the transient current flowing through the Cable Covering Protection Units of the EHV cable line measurement to study sheath over voltage protection. The other is the transient current measurement flowing through the overhead line and the cable conductor connected each other. In case of the EHV cable line, switching surge currents were measured. Beside the case of the overhead line, lightning surge currents were measured. There are good agreement between measured data and the results of EMTP simulation.View full abstractDownload PDF (1021K) -
Kenji Morita, Takashi Imakoma, Morio Nishikawa, Hiroshi Nozaki1994 Volume 114 Issue 1 Pages 60-66
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSTransmission and distribution lines are sometimes hit by lightning strokes and there is some risk of electrical puncture of suspension insulators due to high and steep lightning surge voltage. When the insulators suffer from steep lightning surge voltages, solid insulating body of the insulators is sometimes punctured before external flashover in the air occurs. These characteristics were investigated on the insulators at the laboratory by using different steep impulse voltages.
From the investigation results, both V-t characteristics of external flashover and internal puncture were obtained on the insulators. And it was found out that the puncture of the insulators is a matter of probability, depending on the dimensions of the insulators, steep impulse voltages and number of impulse voltage applica-tion. Especially, effect of number of voltage application on puncture probability was clarified and partial damage by a small number of voltage application was verified before complete puncture occurred. Based on the study results empirical equation relating to probability of puncture (P), impulse voltage (V) and number of voltage application (N) was established.View full abstractDownload PDF (3522K) -
Masayuki Yoda, Kou Suzuki, Iwao Miyachi1994 Volume 114 Issue 1 Pages 67-71
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSTaking part in the triggered lightning experiments at Okushishiku mountain top, Ishikawa, Japan since 1986, the authors have developed portable digital systems for measurment of fullsize lightning current on site with attainable highest accuracy. The principal difficulties under the strong effects of electromagnetic disturbances by close range lightning discharge, such as shielding of electronic circuits and noise clearing, have been successfully overcome from the viewpoints of both hard- and softwares. A coaxial shunt resistance of 1 mΩ, for which, later on, replaced 0.4 mΩ of minimum residual inductance and an A/D converter with sampling rate of 10MS/s are coupled with a host computer through the optical fiber connection. A series of experimentally obtained waveforms of positive lightning currents are considered to reveal obviously the characteristics of original discharge mechanism. To cover up the inherent weakness of digital measurement for unknown quantities, the extended application of those systems has been realized by introducing an optical LAN system of two range current measurement of different sensitivities or three range with an additional voltage element.View full abstractDownload PDF (1429K) -
Takayuki Wakimoto, Tatsuya Harada, Yasuhide Kashiwagi1994 Volume 114 Issue 1 Pages 72-78
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSDigital recorders have been used for impulse high voltage measurements in place of oscilloscopes and the accuracy requirements are specified in detail by the IEC Standard 1083-1: “Digital recorders for measurements in high voltage impulse tests”. Many factors such as sampling rate, non-linearities of amplitude and time base, internal noise level, interference and so on influence the accuracy . If the digital recorder is used in a reference measuring system proposed by the draft of IEC60-2, more accuracy is needed than the requirements specified by IEC1083. In this paper, authors dealt especially with the influence of the internal noise level of the digital recorder on the accuracy and clarified the relation between the accuracy and the internal noise level of the digital recorder for rrreasurements of standard lightning and switching impulse voltages. Furthermore, in order to eliminate the influence of the internal noise, the authors proposed the correction methods and showed that the methods remarkably increased the measuring accuracy for lightning and switching impulse voltage waveforms.View full abstractDownload PDF (1421K) -
Toshiyasu Masakawa, Takahiko Kasamatsu, Naoto Nagaoka1994 Volume 114 Issue 1 Pages 79-84
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSThis paper clarifies a source for estimate error of an input voltage waveform of a capacitive voltage divider, when a frequency transform method is applied. From experimental and numerical analyses, an offset voltage of a digital waveform recorder causes significant error to an estimated voltage waveform. Because the offset voltage acts as DC. error, the effect of the offset is quite significant for an input wave which has more DC. component such as a switching surge waveform compared with a lightning surge.
An offset voltage correction method is proposed in this paper. This method is also applicable to the surge waveform is superposed upon a steady state sinusoidal voltage. Estimated inputs corrected by the proposed method show a good agreement with input voltage wave forms.
The input voltage-waveform estimation-method with the offset correction has quite high generality, and is applicable not only to lightning but also to switching surges.View full abstractDownload PDF (866K) -
Evaluation of Error on Measuring Systems for High Voltage Impulses and their Comparison MeasurementsYasuhide Kashiwagi, Tatsuya Harada, Masamori Saeki, Takayuki Wakimoto, ...1994 Volume 114 Issue 1 Pages 85-90
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSThis paper summarizes the comparison measurements carried out by the authors with the two PTB dividers, A and B, that have been used in International Comparisons at many laboratories in the world, and with a 2m, 10k Ω resistor divider. For full lightning impulse, the difference of peak values measured by the two dividers was less than 0.2% in all cases. The peak value difference increases with a decrease of the time to chopping. In order to evaluate those results, simulations of those comparison measurements were carried out by using a convolution algorithm with measured unit step responses of the measuring systems mentioned above and input impulse waveforms calculated by using EMTP. As a result, the simulated values agree well with the measured ones. Furthermore, similar simulations for several input waveforms were carried out. The simulated results of comparison measurements were influenced by the input waveforms; nevertheless, those waveforms were used to approximate the chopped lightning impulse on previous works.View full abstractDownload PDF (1809K) -
Masaru Ishii, Hiroshi Koyama1994 Volume 114 Issue 1 Pages 91-97
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSIntercomparison tests of dividers for lightning impulse measurement were carried out Japan participated by 12 laboratories. Two resistive dividers, one with 300 kV rating and the other with 1 MV rating, were circulated among the laboratories. The comparison test is one of the methods for checking the uncertainty of a high voltage measuring system, and is proposed in the course of the revision of an IEC standard to incorporate a new idea, that is, the traceability of the uncertainty in high voltage measuring systems.
This paper reports on the determination of the scale factor, evaluation of the unit step response parameters and the comparison tests with lightning impulse voltages at about 100 kV. It is demonstrated that the participating 12 laboratories are all capable of realizing the idea in the revision of the IEC standard, that is, to establish traceability. On the other hand, a few problems to be solved in the testing procedures are found, to reduce the scatter in the measured parameters in these tests.View full abstractDownload PDF (1776K) -
Zhiyong Miao, Keiichiro Yasuda, Ryuichi Yokoyama1994 Volume 114 Issue 1 Pages 98-105
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSIn this paper, we present a new planning technique based on fuzzy set theory in order to solve the dynamic load dispatching problem. In some conventional studies on the dynamic load dispatching, the fuzziness of some parameters which is made by expert's experience and knowledge has been ignored. Furthermore, the fuzziness of the coordination of various objectives, such as economy and the total adjustable capacity of generation, has also been left out of consideration. In this paper, the fuzziness of the load forecast is selected as the fuzziness of parameters, and the fuzziness of the evaluation of economy and the total adjustable capacity of generations are selected as fuzziness of decision making. These fuzziness are treated as fuzzy sets, respectively. Under the fuzzy environment, the fuzzy dynamic load dispatching method is developed on the basis of the Bellman-Zadeh maximizing decision. Arbitrary shape of membership functions can be used in the proposed approach, since the method is based on the dynamic programming technique. The effectiveness and feasibility of the proposed approach are demonstrated on a typical power system model.View full abstractDownload PDF (2078K) -
Yoshihiro Kawase, Tadashi Yamaguchi, Osamu Miyatani, Shokichi Ito1994 Volume 114 Issue 1 Pages 106-111
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSAC electromagnets are widely used for the operating magnets of magnetic contactors, relays and other electromagnetic devices. It is necessary for the optimum design of a new generation of AC electromagnetic devices to obtain the dynamic behavior of the electromagnets. It is very difficult to obtain the dynamic behavior by the 3-D nonlinear analysis, because the displacement of the armature and the applied voltage vary with time. Recently, the 3-D analysis method in which the 3-D electromagnetic field is coupled to the electric circuit and the mechanical system has been developed by the authors. In this paper, the method has been advanced and applied to analyze a clapper type AC electromagnet with a shading coil. The time variations of the exciting current, the attractive force and the displacement of the armature are calculated, and the results calculated are compared with the measurements. Then, it is clarified that the operating characteristics of the AC electromagnet can be accurately calculated.View full abstractDownload PDF (999K) -
Hideomi Takahashi1994 Volume 114 Issue 1 Pages 112-113
Published: January 20, 1994
Released on J-STAGE: December 19, 2008
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1994 Volume 114 Issue 1 Pages e1
Published: 1994
Released on J-STAGE: December 19, 2008
JOURNAL FREE ACCESSDownload PDF (75K)
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