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Volume 116, Issue 10
Displaying 1-13 of 13 articles from this issue
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Yoshifuru Saito1996 Volume 116 Issue 10 Pages 833-839
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSDownload PDF (5787K) -
Hideo Hirose1996 Volume 116 Issue 10 Pages 840-848
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSThe relationship between the V-t characteristic and the 2 parameter Weibull distribution for the dielectric breakdown voltage has long been discussed by engineers and statistical scientists. In this paper, it is revealed from a probabilistic view-point that the slope n in the power-law model, the Weibull shape parameter a in lifetime distribution, and the Weibull shape parameter b in dielectric breakdown voltage distribution have a possible relation, n=b/a, if time is Weibull's random variable with fixed voltage stress in lifetime distribution and voltage stress is also Weibull's random variable with flxed time in the breakdown distribution. However, it has found that this relation does not hold in some experimental tests. The results of statistical analysis for polyethylene insulated cables show such a case; n≠b/a is demonstrated under dry condition of the cables, while n=b/a holds under wet condition. The paper also claims that the adoption of well-known formula, F(t, v)=1-exp{-(t/t0)a(v/v0)b}, is inappropriate in a sense of indefiniteness of t0 and v0.View full abstractDownload PDF (1295K) -
Yoshitaka Nakao, Masashi Naruse, Hidenori Itoh, Yoshio Suzuki, Yosuke ...1996 Volume 116 Issue 10 Pages 849-854
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSThe propagation process of a creepage discharge under a positive impulse voltage application in transformer oil is investigated in detail by means of high speed Schlieren photography and a current measurewent system using LED. In the present work, different sorts of insulating barriers with various thick-ness were placed between a point electrode and a plane electrode. The used voltage is an impulse voltage (1.1/225μs) of magnitude Vm=+30kV.
The main results obtained can be summarized as follows:
(1) When a simple barrier was inserted between a point electrode and a plane electrode, the discharge figure revealed a barrier type dependence.
(2) When barriers were piled up,
(i) the current duration, the charge quantity, and the streamer propagation length decreased with the increase of the number of barriers.
(ii) most attention should be paid to the barrier facing the point electrode.View full abstractDownload PDF (2358K) -
Kiminobu Imasaka, Shinya Hara, Hideyuki Tokudomi, Junya Suehiro, Masan ...1996 Volume 116 Issue 10 Pages 855-860
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSAn exploding fuse is widely used as an opening switch of an inductive pulsed power generator. Characteristics of output voltage of the generator depend mainly on changing rate of the fuse resistance during exploding. In this case, water is generally employed as a surrounding medium of the fuse opening switch in order to cool the fuse vapor during exploding and to prevent the opened switch from restrike arcing.
In this paper, we study effect of the cooling water resistance on the output voltage of the inductive pulsed power generator which has copper wire fuses as an opening switch and proposed improvement method of the output voltage. Effective resistance of the switch is considerably influenced by the water resistance. As a result, output voltage decreases if the water resistance is low. It is shown that the apparent water resistance and the output voltage can be increased by using an insulator in the water vessel.View full abstractDownload PDF (1293K) -
Shigeru Kato, Masanori Kobayashi1996 Volume 116 Issue 10 Pages 861-867
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSFor the circular cone placed in a uniform axial magnetic field, the surface magnetic charge densities are numerically calculated by the surface magnetic charge simulation method. From the results the surface magnetic charge density distributions and demagnetizing factors ( ballistic, magnetometric and partial demagnetizing factors) are obtained and illustrated for various cases of different aspect ratios (tip angles of cone) and relative permeabilities. Especially, those characteristics around the tips of cones are shown in detail and the behavior at the tips is discussed.View full abstractDownload PDF (793K) -
Manabu Higashi, Kan-ichi Fujii1996 Volume 116 Issue 10 Pages 868-872
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSThe exhaust gas from diesel engine is one of the major cause of air pollution. As one method, for pollution control, the authors have been developed plasma reactors. The authors' reactor is concentric cylinder type which has a glass tube barrier between electrodes. Connecting two of these reactors in series, the NOx(NO+NO2) component from diesel engine exhaust gas is decomposed up to 93%.
This reactor was mounted on 3 Iitters diesel engine and received 6 modes load testing at an authorized public facility (JARI, Tukuba-city) and cleared the legal critical value 350 ppm of NOx. By this success, the effectiveness of discharge plasma treatment of diesel exhaust gas and its practical evalution have been confirmed.View full abstractDownload PDF (1185K) -
Zhen-chao Wang, Hiroyasu Yoshizuka, Koji Takano, Masanori Hara1996 Volume 116 Issue 10 Pages 873-880
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSIn large superconducting magnets, liquid helium is usually used both as coolant and electrical insulator. An abnormal high voltage and thermal bubbles often appear simultaneously during the quenching period. Such an incident is thought serious from a point of view of electrical insulation. In this work, thermal bubble behavior affected by the electrostatic forces in liquid helium and electrical breakdown mechanism of liquid helium are studied under the simulating quench condition of S. C magnet. The results show that (1) the electrostatic forces produced by nonuniform electric field are useful for reducing the effect of thermal bubbles on electrical breakdown in almost all cases, although the bubble aggregation occurs in the region where the gradient force is counterbalancing with the buoyancy and (2) the fins on the surface of superconducting wires are helpful to prevent the bubbles from being released into strong field region if the groove between fins is formed along the field decreasing direction on the wire surface.View full abstractDownload PDF (3438K) -
Keisuke Ishii, Kwang Soo Seol, Yoshimichi Ohki, Hiroyuki Nishikawa1996 Volume 116 Issue 10 Pages 881-885
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSMicroscopic structural randomness in SiO2, a typical electrical insulating material, was evaluated by observing the decay profile of the photoluminescence due to the oxygen vacancy (≡Si-Si≡). As the samples with different degrees of randomness, an ionimplanted thermal SiO2 film, SiO2 films formed by plasma-enhanced chemical vapor deposition of tetraethoxysilane with and without doped fluorine, a buried oxide film prepared with the method of separation by ion-implanted oxygen (SIMOX), and a bulk silica glass prepared by the soot-remelting method were tested. By analyzing the decay profile with a stretched-exponential function, it was found that the deviation of the decay profile from a single exponential function is larger in the sample whose structural randomness is presumed to be larger from the measurements of infrared absorption and the chemical etch rate in HF solution.View full abstractDownload PDF (914K) -
Kenji Ichikawa, Tatsuo Motoyama1996 Volume 116 Issue 10 Pages 886-892
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSRecently, the application of fiber reinforced plastics (FRP) for high-voltage use has rapidly increased. In particular, unidirectionally pultruded FRP rods have become indispensable for composite insulators or handling rods of circuit breakers and so on. Therefore, they are always required of the stable and excellent breakdown properties. As they are comprised of bundles of glass fibers and epoxy resin, and have a lot of internal microscopic interfaces which affect the breakdown properties.
In this paper, two kinds of unidirectionally pultruded FRP rods with voids and no void were prepared, and their electric breakdown characteristics were studied about the differences of the kind of the applied voltage, the interface angles (angle between the direction of glass fibers and that of rod electrode), and about the influence of the moisture ingression to FRP, medium existing around the rod electrode. Furthermore, the photographic observation of breakdown path and other places of FRP by means of Scanning Electron Microscope device and the electric field analysis by means of the computer software were conducted.View full abstractDownload PDF (3820K) -
Tsuginori Inaba, Hiroyuki Oi, Masao Endo1996 Volume 116 Issue 10 Pages 893-894
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
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Shinji Kawada, Motoshigc Yumoto, Takao Sakai1996 Volume 116 Issue 10 Pages 895-896
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSDownload PDF (796K) -
Shuji SATO1996 Volume 116 Issue 10 Pages 897-898
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
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Yasutaka Kishimoto, Kosaku Yoshida, Hiroaki Tagashira1996 Volume 116 Issue 10 Pages 899-900
Published: September 20, 1996
Released on J-STAGE: July 15, 2008
JOURNAL FREE ACCESSDownload PDF (928K)
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