Motion Of Metallic Particles Research Articles

Metallic particle motion and breakdown characteristics in GIS with 0.1‐Hz VLF (very low frequency) high voltage applied

AbstractVLF (Very Low Frequency) high voltage with frequency of 0.1 Hz will be utilized for an on‐site test of XLPE underground cables, instead of conventional dc high voltage test. Since XLPE cables are connected to GIS (Gas Insulated Switchgears) in substations, the influence of VLF voltage application to GIS insulation should be investigated. One of the most important characteristics for GIS insulation lies in the metallic particle contamination and its behavior, which may induce breakdown in GIS.From the above viewpoint, this paper discusses the metallic particle behavior and breakdown characteristics under VLF voltage application in GIS. Experimental results revealed that (1) Particle motion under VLF condition was similar to that under dc condition, while specific in the transient behavior at the polarity reversal. (2) Breakdown was induced by particles located in the vicinity of high voltage conductor at the instance of crossing the gap or in the firefly conditions. (3) Breakdown voltage in positive half cycle was higher than that in negative half cycle at the lower gas pressure, while lower at the higher gas pressure, which was attributed to the particle behavior and the breakdown mechanism of SF6 gas.Consequently, metallic particles in GIS under VLF voltage application exhibited the specific behavior associated with the slow change of instantaneous voltage and polarity, and resulted in the complex pressure dependence of breakdown characteristics. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(4): 33–40, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.1166

Dynamic analysis of motion of spherical metallic particles in non-uniform electric field

This paper presents a theoretical analysis of the dynamics of motion of spherical metallic particles under non-uniform fields for direct-current gas-insulated switchgear (dc GIS) and for electrostatic separators/sizers (ESS). The particle equations of motion between a pair of diverging conducting plates are numerically solved in three dimensions using a computational algorithm. The upper plate is energized by HV dc or HV ac of variable frequency, while the lower one is grounded. In the case of ESS, the lower electrode is also mounted horizontally on a vibratory conveyor. The results reveal that the particle exhibits several phenomena during motion depending on its initial position, radius and density, angle between the diverging plates, tilt angle of the electrode system, and frequency and amplitude of the applied voltage. The influence of vibratory-conveyor variables on the separation/sizing process is studied in the light of the particle trajectory in the third dimension. Moreover, the results are interpreted using dimensional analysis. The use of HV ac causes the separation/sizing process to be imprecise; the higher the applied-voltage frequency and the larger the particle radius, the higher is the risk of breakdown. Depending on the tilt angle and orientation of the earthed electrode relative to the divergent angle between the electrodes, particle trapping can be helped or hindered. Therefore, several factors should be taken into consideration in the design and installation of the particle drivers and traps in GIS. Finally, the effects of dielectric coating on the electrode and of gas pressure on the particle trajectory are also studied.

0.1Hz超低周波(VLF)交流高電圧印加時におけるGIS内金属異物挙動と絶縁破壊特性

0.1Hz超低周波(VLF)交流高電圧印加時におけるGIS内金属異物挙動と絶縁破壊特性

Motion of metallic particles in gas insulated systems

The presence of metallic contamination can seriously reduce the insulation performance of a gas insulated system (GIS). This presentation is focused on the motion of elongated particles, since these particles are considered the ones most frequently found in GIS. The aim of the work has been to learn more about the motion and thereby to suggest improvements to the models that traditionally have been used. With a good model, a more accurate calculation of the motion of a particle and, in turn, a better estimation about its severity in a system can be made.

Mass Transfer and Particle Motion in a Barrel Plater

This paper describes a study of mass‐transfer process and particle motion in a plating barrel. The mass‐transfer coefficient was measured with a diffusion‐controlled metal‐dissolution reaction, and the motion of metal particles was examined with a video recording system. Three kinds of particle motion were observed in a horizontal barrel: (i) slumping motion at a low barrel rotational speed of 3 rpm; (ii) falling motion at the barrel rotational speeds of 6 to 13 rpm; and (iii) cascading motion at 15 to 17 rpm. When the barrel was tilted at an angle of 30 to 60° from the horizontal position, the particles in the lower portion of the barrel rotated like a rigid body. There was no relative particle movement in this regime. The falling motion of particles occurred only near the top surface of the particle load. At a barrel tilt angle of 90° (i.e., a vertical barrel), all the particles rotated like a rigid body, and no falling layer was observed. The mass‐transfer rate to the particles increased with increasing barrel rotational speed, and decreased with increasing tilt angle from the horizontal position. When the barrel tilt angle was less than 60°, the mass‐transfer rate decreased with increasing barrel loading. The effect of barrel loading on mass transfer decreased with increasing tilt angle; at a barrel tilt angle of 90° the barrel loading had a negligible effect on the mass‐transfer rate in the barrel. A set of empirical equations was obtained to correlate the Sherwood number to the Reynolds number, Schmidt number, Grashof number, barrel tilt angle, barrel loading, and barrel immersion.

The motion of charged metal particles within parallel and tilted electrodes

In a gas insulated switchgear, metal particles which might exist unexpectedly lower the breakdown voltage extensively. This study is concentrated on the motion of charged metal particles within parallel and slightly tilted electrodes to which high voltage DC or AC voltage is applied. The motion of various sizes of metal sphere particles was observed by using a normal and also by a high speed video camera. At first, the motion of a sphere is theoretically predicted. It was shown that there exist two different critical voltages at which the motion of a particle starts and stops. The experimental results were compared with theoretical prediction and showed good agreement with them. One of the interesting results with a slightly tilted electrodes is that the motion of particle is confined within a certain region.

A theoretical study of metallic particle motion and particle‐initiated breakdown in GIS

Electrical Engineering in JapanVolume 109, Issue 1 p. 22-30 Article A theoretical study of metallic particle motion and particle-initiated breakdown in GIS Satoshi Matsumoto, Satoshi Matsumoto Toshiba CorporationSearch for more papers by this authorHirokuni Aoyagi, Hirokuni Aoyagi Toshiba CorporationSearch for more papers by this authorHitoshi Okubo, Hitoshi Okubo Toshiba CorporationSearch for more papers by this authorNobumitsu Kobayashi, Nobumitsu Kobayashi Toshiba CorporationSearch for more papers by this authorSatoru Yanabu, Satoru Yanabu Toshiba CorporationSearch for more papers by this author Satoshi Matsumoto, Satoshi Matsumoto Toshiba CorporationSearch for more papers by this authorHirokuni Aoyagi, Hirokuni Aoyagi Toshiba CorporationSearch for more papers by this authorHitoshi Okubo, Hitoshi Okubo Toshiba CorporationSearch for more papers by this authorNobumitsu Kobayashi, Nobumitsu Kobayashi Toshiba CorporationSearch for more papers by this authorSatoru Yanabu, Satoru Yanabu Toshiba CorporationSearch for more papers by this author First published: January/February 1989 https://doi.org/10.1002/eej.4391090103Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume109, Issue1January/February 1989Pages 22-30 RelatedInformation

Far-infrared absorption by small metallic particles in a spherical oscillator well

We examine, from the quantum-mechanical point of view, the vibrational motion of small metallic particles contained in amorphous materials and its contribution to the far-infrared absorption by these composite media. Temperature effects are considered. The results are discussed and compared with experimental data.

Metallic Particle Motion in 3-Phase SF6 Gas Insulated Bus

Metallic Particle Motion in 3-Phase SF₆ Gas Insulated Bus

Metallic Particle Motion in 3-Phase SF6 Gas Insulated Bus

To investigate the behavior of metallic particles in 3-phase gas insulated buses (3-phase GIB), we conducted a test by using a 3-phase 275kV, ac, 60Hz full-scale model. The test results revealed that in a 3-phase electric field, unlike in a single-phase field, metallic particles were trapped on and around the high-voltage conductors and revolved circumferentially. Computer analysis shows that it was closely related to locational and periodic changes in the electric field provided by the 3-phase GIB, and that there were points on the high-voltage conductors in which metallic particles were readily trapped. It also was proved that phenomena peculiar to the 3-phase GIB could be reproduced very well by computer simulation.