Influence of Switching Impulse Wave Shape on Flashover Voltages of Air Gaps

Harada, Tatsuya; Aihara, Yoshinori; Aoshima, Yoshihide

doi:10.1109/tpas.1973.293675

Cited by 27 publications

(5 citation statements)

References 9 publications

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“…In those studies, the flashover tests were performed by using three kinds of positive polarity (S.I): exponential, damped oscillatory and linearly rising impulses. They demonstrated that the time to crest related to the minimum 50% flashover voltage for exponential impulse is shortest, and is longer for damped oscillatory and linearly rising impulses [10]. According to the literature, the long air gap discharge provided positive polarity in a three-meter rod-plane configuration, which was confirmed using double exponential switching impulses of different front times.…”

Section: Introductionmentioning

confidence: 86%

Continuous and Discontinuous Streamer Leader Propagation Phenomena under Slow Front Impulse Voltages in a 10-meter Rod-Plane Air Gap

Shah

et al. 2018

Energies

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Investigation of positive streamer-leader propagation under slow front impulse voltages can play an important role in the quantitative research of positive upward lightning. In this work, we performed a large-scale investigation into leader development in a 10-m rod–plane gap under a long front positive impulse. To describe the leader propagation under slow front impulse voltages, we recorded the leader propagation with a high-speed charge coupled device (CCD) camera. It is important to figure out this phenomenon to deepen our understanding of leader discharge. The observation results showed that the leader mechanism is a very complex physical phenomenon; it could be categorized into two types of leader process, namely, continuous and the discontinuous leader streamer-leader propagation. Furthermore, we studied the continuous leader development parameters, including two-dimensional (2-D) leader length, injected charge, and final jump stage, as well as leader velocity for rod–plane configuration. We observed that the discontinuous leader makes an important contribution to the appearance of channel re-illuminations of the positive leader. To clarify the above doubts under long front cases, we carried out extensive experiments in this study. The comparative study shows better results in terms of standard switch impulse and long front positive impulse. Finally, the results are presented with a view toward improving our understanding of propagation mechanisms related to restrike phenomena, which are rarely reported.

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Section: Introductionmentioning

confidence: 86%

Continuous and Discontinuous Streamer Leader Propagation Phenomena under Slow Front Impulse Voltages in a 10-meter Rod-Plane Air Gap

Shah

et al. 2018

Energies

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“…The development of equipment operative at higher voltages is continuous, where testing and simulating have become a great tool for the designers. Most of the tests involve high voltage lightning-or switching-like impulses applied to different electrode configurations, representing most of the constructive possibilities, aiming to find the 50% probability breakdown voltage (U 50% ) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Experimental study of leader tortuosity and velocity in long rod-plane air discharges

Díaz

Hettiarachchi

Rahman

et al. 2016

IEEE Trans. Dielect. Electr. Insul.

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Long air gap electrical discharges are of particular interest among scientists and engineers working on high voltage techniques and lightning research. In the present work we report experimental results obtained while testing a long rod-plane air gap with positive switching-like voltage impulses to study the velocity and tortuous progression of the leader discharge. Voltage and current waveforms were recorded. Two still digital cameras were used to track the leader tortuous path. By using a fast digital camera, the leader temporal evolution was recorded and its propagation velocity was estimated. Three angles were used to describe the leader tortuous progression.

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“…• the lower part of the impulse has no significant effect on leader inception or breakdown [27]; this follows from comparative tests with double exponential impulses obtained from an impulse generator and a 1-cosine form generated by switching an HV test transformer [28]; • the longer the air gap is, the less sensitive the critical breakdown characteristics are to the impulse front [28] so that the value of used to fit the upper part of the field curve is not critical; • based on similar arguments, it has been previously shown [29] that for shorter lightning rods, double exponential impulses with front times in the range 200 s-1 ms are suitable to simulate upward leader inception; subsequently, double exponential impulses of 250 s and 580 s fronts were used for lightning simulation tests on 0.5 m and 1.0 m lightning rods [29]. Consider a lightning rod of radius r and height h over flat ground in an ambient relative air density .…”

Section: Leader Inceptionmentioning

confidence: 99%

Modeling of Lightning Exposure of Sharp and Blunt Rods

Rizk

2010

IEEE Trans. Power Delivery

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Corona characteristics of lightning rods exposed to ambient fields due to cloud charges prior to negative leader descent are analyzed, taking into account rod slenderness and relative air density. A new formula is introduced to account for the effect such corona on upward connecting leader initiation. This quantifies the tendency of a sharp lightning rod towards self-shielding, which can be detrimental to the protection of a nearby object, particularly if this object is less susceptible to corona formation. The effect of corona due to cloud charge fields on the attractive radius of a solitary rod is also investigated. Based on discharge physics, the characteristics of a non-self shielding air terminal are then defined. Since large electrodes are susceptible to deteriorating corona performance due to protrusions and water drops, preference is given to a corona-free rod with the smallest diameter, under cloud charge fields. For tall rods or rods exposed to high ambient fields, however, the required diameter of a hemispherically capped rod may be impractical. The physical approach described in this paper satisfactorily accounts for the lightning performance of competing sharp and blunt rods in a previous field investigation.

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Influence of Switching Impulse Wave Shape on Flashover Voltages of Air Gaps

Cited by 27 publications

References 9 publications

Continuous and Discontinuous Streamer Leader Propagation Phenomena under Slow Front Impulse Voltages in a 10-meter Rod-Plane Air Gap

Continuous and Discontinuous Streamer Leader Propagation Phenomena under Slow Front Impulse Voltages in a 10-meter Rod-Plane Air Gap

Experimental study of leader tortuosity and velocity in long rod-plane air discharges

Modeling of Lightning Exposure of Sharp and Blunt Rods

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