Flashover along cylindrical insulating surfaces in a nonuniform field under positive switching impulse voltages

Lazaridis, L.A.; Mikropoulos, Pantelis N.

doi:10.1109/tdei.2008.4543106

Cited by 18 publications

(10 citation statements)

References 14 publications

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“…Generally, at a particular pressure, the flashover strength of the system either stayed consistent, or increased slightly, from <10% RH to ~50% RH. With no spacer ('Air'), increasing humidity did not have a significant effect on the breakdown strength; this applied for all tested pressures, and was also observed in [13]. When a solid spacer was included, increasing relative permittivity did not result in the general trends seen during the negative polarity tests.…”

Section: Figssupporting

confidence: 51%

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Impulsive Flashover Characteristics and Weibull Statistical Analysis of Gas-Solid Interfaces With Varying Relative Humidity

et al. 2020

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This paper informs on the flashover strength of three materials: Delrin (polyoxymethylene), HDPE (high-density polyethylene) and Ultem (polyetherimide) with smooth surface finishes, in zero-grade air at −0.5, 0 and 0.5 bar gauge, and at <10%, ~50% and >90% relative humidity (RH). Both negative and positive polarity impulse voltages were applied to investigate the potentially asymmetrical electrical performance of the geometrically-symmetrical electrode arrangement. In all tests, high voltage (HV) impulses with a nominal 100/700 ns wave-shape were applied. Each test conformed with the ASTM D3426-97 standard of 'step up' testing, to find the average flashover voltage for each set of conditions. For negative polarity, each solid dielectric material demonstrated a decrease in flashover voltage as the RH was increased. For positive polarity, however, the flashover voltages were similar for all levels of RH, with the exemption of HDPE. A decrease in flashover voltage was found as the permittivity of the material increased for negative polarity, irrespective of humidity and pressure. Overall, the highest flashover voltage recorded for negative polarity was ~200 kV with an HDPE spacer, at 0.5 bar gauge and <10% RH. The poorest performance was for a Delrin spacer in negative polarity, at −0.5 bar gauge and >90% RH, at a value of ~53 kV. For positive polarity, the highest flashover voltage was for a Delrin spacer at ~50% RH and 0.5 bar gauge, with a voltage of ~180 kV; the lowest flashover voltage of ~60 kV was recorded with an HDPE spacer, at −0.5 bar gauge and >90% RH.

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Section: Figssupporting

confidence: 51%

“…Under positive polarity, however, the same effect was not observed. This is due to different breakdown processes affecting the initiation and propagation of the discharge, including higher probability of bulk air breakdown, away from the surface of the spacer [3], [13], [19].…”

Section: A Materialsmentioning

confidence: 99%

Impulsive Flashover Characteristics and Weibull Statistical Analysis of Gas-Solid Interfaces With Varying Relative Humidity

et al. 2020

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“…As a matter of fact, the experimental investigations in this paper [25] also confirm that rainfall could considerably lower the breakdown voltage of a large gap under switching impulses, for both positive and negative polarities. Apparently, as the air permittivity/conductivity increases, the breakdown voltage decreases under lightning impulses [25][26][27][28]. • For the same feeder length, the covered conductor feeder attenuates surges more than the underground cable feeder.…”

Section: Discussionmentioning

confidence: 99%

Modelling and evaluation of the lightning arc between a power line and a nearby tree

Omidiora

Elkalashy

Lehtonen

et al. 2011

Int Trans Elec Energy Syst

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SUMMARY This paper addresses the modification of the existing dynamic arc model for lightning arc simulation application. The modified dynamic arc model combines the static and the dynamic arc equations that are already established in the literature to reproduce an arc fault involving a lightning‐struck tree and a nearby power distribution line during rainfall. The results of experimental studies regarding arc creation between a tree and a nearby power line with artificial rainfall were obtained. A complete model of this phenomenon is reproduced using the electromagnetic transient program (ATP/EMTP) and the existing static and dynamic arc equations. The essential reason for modifying this model is graphically shown with a comparison of the dynamic arc and the modified dynamic arc models. The performance of the arc phenomenon was examined using a typical Finnish distribution network design. By means of simulation using the modified dynamic arc, developed within the ATP/EMTP software with its Transient Analysis Control System features, the lightning arc performance of the MV/LV network under the influence of nearby trees and the network characteristics is analyzed. It is expected that such a model can be included in the existing ATP/EMTP software packages for simulating power system transients. Copyright © 2011 John Wiley & Sons, Ltd.

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“…Charge deposition by surface corona streamers on insulating surfaces has been shown to occur under lightning impulses [6][7], [13][14]. Surface charge accumulation due to coronas might also affect the discharge path at breakdown [14][15][16][17]; in the present dielectric covered rod/plane gaps there were cases where breakdown occurred solely in free air. More work is needed to further elucidate the observed effects of the dielectric cover on breakdown by employing also a surface charge measuring technique.…”

Section: Discussionmentioning

confidence: 99%

Impulse breakdown of short rod-plane air gaps with a dielectric covered rod

Mavroidis

Mikropoulos

Stassinopoulos

et al. 2008

2008 43rd International Universities Power Engineering Conference

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Results are presented concerning breakdown of short rod-plane air gaps with a dielectric-covered rod under positive standard lightning and switching impulse voltages. Breakdown probability distributions were obtained through multiple level tests and the time and voltage to breakdown were measured with the gap length as a parameter. The simple air gaps with a bare rod were considered as reference cases. There is an increase in the dielectric strength of the gap due to the insulating cover, especially under switching impulse voltages. In the presence of the dielectric cover the effect of the impulse waveform on the dielectric strength of the gap is minimal.

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Flashover along cylindrical insulating surfaces in a nonuniform field under positive switching impulse voltages

Cited by 18 publications

References 14 publications

Impulsive Flashover Characteristics and Weibull Statistical Analysis of Gas-Solid Interfaces With Varying Relative Humidity

Impulsive Flashover Characteristics and Weibull Statistical Analysis of Gas-Solid Interfaces With Varying Relative Humidity

Modelling and evaluation of the lightning arc between a power line and a nearby tree

Impulse breakdown of short rod-plane air gaps with a dielectric covered rod

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