Propagation of electrical tree structures in solid polymeric insulation

Dissado, L.A.; Dodd, S.J.; Champion, J.V.; Williams, P.I.; Alison, J.

doi:10.1109/94.598282

Cited by 129 publications

(78 citation statements)

References 39 publications

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“…However, the average PD magnitudes decrease at high values of temperature and/or humidity, while the corresponding number of PDs per second increases significantly. At the same conditions, the corresponding tree growth times are very short and indicate a runaway process [4]. Hence, the PD rates can be used to differentiate between the two modes, electrical treeing and runaway.…”

Section: Resultsmentioning

confidence: 99%

Pulse sequence analysis on PD data from electrical trees in flexible epoxy resins

Chalashkanov

Dodd

Dissado

et al. 2011

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent University of Leicester Department of EngineeringAbstract-The Pulse Sequence Analysis (PSA) was carried on PD data from electrical trees grown in flexible epoxy resins. The samples used for the electrical tree experiments were conditioned in environments with different relative humidity in the range 15-100% prior to the electrical tests and the corresponding moisture content in the samples was between 0.1 and 6.9%. The electrical treeing experiments were carried out at different temperatures in the range 20-70°C. The details of PD dynamics during the electrical tree growth have been found to change significantly with temperature and absorbed moisture. In this paper, it is shown that PSA could be successfully used to discriminate between PD data from electrical trees and runaway breakdown.

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Section: Resultsmentioning

confidence: 99%

Pulse sequence analysis on PD data from electrical trees in flexible epoxy resins

Chalashkanov

Dodd

Dissado

et al. 2011

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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“…Trees initiated in the bulk material [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] are orientated along the lines of the applied electrical field. Electrical trees have been found to grow at a decelerating rate [Dissado, et aL, 1997] until a certain point is reached when an acceleration of the growth rate occurs (resembling an avalanche effect) leading to electrical breakdown.…”

Section: Electrical Treesmentioning

confidence: 99%

“…[Dissado, et aL, 1992]. Dissado, (1997) however postulates that the "... electrical trees in solids which demonstrate a fractal structure and decelerating growth rate are a consequence of a deterministic breakdown mechanism operating in a regime of deterministic chaos, rather than runaway".…”

Section: Electrical Treesmentioning

confidence: 99%

Investigation of the structural changes in LDPE and XLPE induced by high electrical stress

Sayers¹

2000

Eighth International Conference on Dielectric Materials, Measurements and Applications

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SummaryHigh voltage electrical cables play an immensely important, although largely unseen, part in the lives of everybody in the world today. They are mostly buried underground and provide trouble free operation for the majority of their operational lives. However, the polymer based insulation that is used for a large number of high voltage cables is subject to long term ageing which can eventually lead to electrical breakdown. This ageing manifests itself as the appearance of tree like structures in the bulk polymer insulator. The growth of a tree frequently starts on the boundary of the polymer at the so-called "polymer-semicon" interface.This thesis is concerned, however, with the changes that must take place in the polymer before the tree is formed.Previous investigations of field induced changes occurring within polymer insulation have involved cutting the polymer to expose the region of interest: this is not a satisfactory as the cutting process can produce changes in the polymer. To avoid this a novel technique was developed whereby the polymer-semicon interface can be exposed without cutting the polymer.The interface region of the polymer in contact with the plane electrode was examined and even though the field in this region is less than at the point, it can be sufficiently large to induce structural change in the polymer, readily detectable by Raman spectroscopy.In studies of both LDPE and XLPE, we find evidence of structural change within the polymer and most significantly of considerable Raman fluorescence which is indicative of defect states in the polymer. The latter becomes modified as the polymer structure approaches electrical failure.The observations reported are set in context by the examination of the work of relevant authors and some conclusions deduced. The evidence supports a model in which the forces induced by the electrical field lead to failure by the mechanisms of local yield, microvoid craze and crack formation commonly invoked for the mechanical fracture of polymeric solids. Acknowledgments I would like to thank the School of Informatics, University of Wales, Bangor for all the help and assistance provided not only through the period of this PhD but also during my degree course. I would like to thank the people who worked at BICC Cables Limited before it became BICC General and then was sold to Pirelli Cables who closed BICC down. I would also like to thank the EPSRC for funding this work through a Co-operative Award in Science and Engineering (CASE) studentship.As a result of these connections I have had the pleasure and honour of working with Professor T. J. Lewis and Doctor J. P. Llewellyn both of whom continue to astound me with their ability to absorb new ideas, generate original ideas and furthermore to critically review those ideas and theories. Doctor Carl. Griffiths, previously of BICCGeneral provided invaluable critical appraisal of the work, results and interpretations presented here. I would also like to thank Dr Steven Befteridge, also previously of BICCGeneral, for h...

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“…It has a current of a few μA, as well as polarity effects [8]. Likewise, if a corona discharge continues in electrical equipment, it decreases the dielectric strength and causes insulation breakdown.…”

Section: Local Dischargementioning

confidence: 99%

Frequency Spectrum Analysis of Electromagnetic Waves Radiated by Electric Discharges

Park¹,

Kil²,

Cheon³

et al. 2012

Journal of Electrical Engineering and Technology

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-In this paper, we analyzed the frequency spectrum of the electromagnetic waves radiated by an electric discharge as a basic study to develop an on-line diagnostic technique for power equipment installed inside closed-switchboards. In order to simulate local and series arc discharges caused by an electric field concentration and poor connections, three types of electrode systems were fabricated, consisting of needle and plane electrodes and an arc generator meeting the specifications of UL 1699. The experiment was carried out in an electromagnetic anechoic chamber, and the measurement system consisted of a PD free transformer, a loop antenna with a frequency bandwidth of 150 kHz-30 MHz, an ultra log periodic antenna with a frequency bandwidth of 30 MHz-2 GHz, and an EMI test receiver with a frequency bandwidth of 3 Hz-3 GHz. According to the experimental results, the frequency spectra of the electrical discharges were widely distributed across a range of 150 kHz-400 MHz, depending on the defects, while commonly found between 150 kHz and 10 MHz. Therefore, considering the ambient noise and antenna characteristics, the best frequency bandwidth for a measurement system to monitor abnormal conditions by detecting electromagnetic waves in closedswitchboards is 150 kHz-10 MHz.

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Propagation of electrical tree structures in solid polymeric insulation

Cited by 129 publications

References 39 publications

Pulse sequence analysis on PD data from electrical trees in flexible epoxy resins

Pulse sequence analysis on PD data from electrical trees in flexible epoxy resins

Investigation of the structural changes in LDPE and XLPE induced by high electrical stress

Frequency Spectrum Analysis of Electromagnetic Waves Radiated by Electric Discharges

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