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Proceedings ArticleDOI

Understanding Hydrophobicity Recovery of Silicone Rubber Material Post Corona Ageing

01 Dec 2018-pp 407-411

TL;DR: Results indicate that surface potential and its decay time constant reduces drastically after the corona ageing, as compared to the virgin specimen, however, the test specimens regain their hydrophobicity, though at a different rate, with time.
Abstract: Surface hydrophobicity recovery of silicone rubber insulating material post corona ageing is reported in the present work. Recovery rate of hydrophobicity of uncleaned (S1) and cleaned sample (S2) after the corona ageing are compared. Results indicate that surface potential and its decay time constant reduces drastically after the corona ageing, as compared to the virgin specimen. However, the test specimens regain their hydrophobicity, though at a different rate, with time. Trap distribution characteristic shows that the characteristic time and charge trap depth reduces with the corona aged specimens and regain with rest period. A similar trend is observed with contact angle and corona inception voltage (CIV) of the test specimens. Pattern classification of Ultra High Frequency (UHF) discharge signal is done using modified Chaotic Analysis (CA).
Topics: Peek's law (52%), Silicone rubber (51%)
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Journal ArticleDOI
Faiza1, Abraiz Khattak1, Safi Ullah Butt1, Kashif Imran1  +7 moreInstitutions (3)
25 Jun 2021-Materials
TL;DR: In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites, which showed the best resistance against the applied stresses.
Abstract: Silicone rubber is a promising insulating material that has been performing well for different insulating and dielectric applications. However, in outdoor applications, environmental stresses cause structural and surface degradations that diminish its insulating properties. This effect of degradation can be reduced with the addition of a suitable filler to the polymer chains. For the investigation of structural changes and hydrophobicity four different systems were fabricated, including neat silicone rubber, a micro composite (with 15% micro-silica filler), and nanocomposites (with 2.5% and 5% nanosilica filler) by subjecting them to various hydrothermal conditions. In general, remarkable results were obtained by the addition of fillers. However, nanocomposites showed the best resistance against the applied stresses. In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites. The inclusion of 5% nanosilica showed the best results before and after applying aging conditions.

1 citations


Cites background from "Understanding Hydrophobicity Recove..."

  • ...It shows both degradation and recovery during environmental aging [3,4]....

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Proceedings ArticleDOI
Palash Mishra1Institutions (1)
26 Feb 2021-
Abstract: Composite insulators with polymeric housing are been increasingly used over porcelain and glass insulators in outdoor high voltage insulation structures due to some specific advantages such as light weight, high mechanical strength and better contamination resistance. Among several other used housing material silicone rubber (SIR) is highly preferred for electric power transmission networks operating at an extra-high voltage (EHV) and ultra-high voltage (UHV) levels because of its high hydrophobicity and hydrophobicity transfer capability. However, being organic in nature, polymeric housings degrade gradually with time and accessing their long-term service performance is a big issue. In general, twelve parameters are being identified by CIGRE WG D1-14 to access the health of polymeric insulating material and standardized test methods for accessing eight properties have already been specified. Therefore, this work comprehensively reports the state of the art with regard to the condition monitoring techniques/test methods being adopted for evaluating remaining four parameters viz. hydrophobicity, the resistance against corona discharge, flammability and UV weathering.

References
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Journal Article

28,684 citations


"Understanding Hydrophobicity Recove..." refers background in this paper

  • ...The charges deposited over the surface due to the corona discharges may distort the electric field distribution over the surface thereby affecting the flashover characteristic the insulator [4-6]....

    [...]


Journal ArticleDOI
G. C. Montanari1Institutions (1)
TL;DR: The goal is to show how much space charge can contribute directly or indirectly, through local electric field magnification or alteration, to increase ageing rate or even trigger more energetic, thus faster, degradation processes in insulation design and electrical apparatus long-term performance/reliability.
Abstract: Considering the title of this paper, one might think that everything has been said, shown, proven and discussed already on ageing and failure of electrical insulating materials, based on at least half century of research work and field feedbacks. However, perhaps there is still room to collect ideas and speculate on apparently proven or brand new concepts, such as the interrelation between ageing mechanisms and physically measurable quantities such as space charge, partial discharges and conduction current. The latter is, indeed, the scope of this paper, which is taken from the Whitehead Memorial Lecture given at the 2010 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP). On one hand we will revisit the concepts of space charge accumulation in insulating (polymeric) materials, considering also the latest achievements which deal with ultra-fast charge pulses (solitons), on the other hand we will discuss how space charge can contribute to ageing rate under dc, ac or impulsive voltage, directly through electric field alteration, or indirectly modifying a fundamental ageing factor such as partial discharges.The goal is, at the very end, to show how much such basic investigations can have a fundamental impact on insulation design and electrical apparatus long-term performance/ reliability.

205 citations


"Understanding Hydrophobicity Recove..." refers background in this paper

  • ...The charges deposited over the surface due to the corona discharges may distort the electric field distribution over the surface thereby affecting the flashover characteristic the insulator [4-6]....

    [...]


Journal ArticleDOI
A.J. Phillips1, D.J. Childs2, H.M. Schneider2Institutions (2)
Abstract: The fundamental principles of water drop corona as an aging mechanism for nonceramic insulators are presented. It is demonstrated that water drops in the sheath regions enhance the electric field and may cause corona which can play an important role in long-term performance. Electric field enhancement caused by water drops in different locations on the shed and sheath are demonstrated by means of electric field calculations and small scale experiments. The threshold magnitude of the surface electric field for corona from water drops is presented for two silicone rubber surfaces having different hydrophobic properties. The effect of water drop corona activity on the properties of the surface material is shown using small scale aging experiments.

175 citations


"Understanding Hydrophobicity Recove..." refers background in this paper

  • ...The very reason is their properties like low surface energy, high vandalism resistance, less weight, better contamination performance, high hydrophobicity and the most importantly their self-heating nature or temporary loss of hydrophobicity.[1-3] The study of the surface potential or charge decay is an effective tool in investigating charge carrier transport processes....

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Journal ArticleDOI
Abstract: Space charge formation in polymeric materials can cause some serious concern for design engineers as the electric field may severely be distorted, leading to part of the material being overstressed At the worst, this may result in material degradation and possibly premature failure It is therefore important to understand charge generation, trapping, and detrapping processes in the material In the present paper, the characteristics of charge trapping and detrapping in low density polyethylene under dc electric field have been investigated using the pulsed electroacoustic technique It has been found that the charge decay shows very different characteristics for the sample with different periods of electric field application To explain the results a simple trapping and detrapping model based on two trapping levels has been proposed Qualitative analysis revealed the similar features to those observed experimentally

158 citations


Journal ArticleDOI
Abstract: This paper surveys the properties which give silicone rubber its distinctive and highly desirable performance characteristics for use as outdoor insulation. The methods of assessing these properties arediscussed and this is followed byadetailedsurveyof whatis knownof agingaud recovery mechanisms. Corona is identified as the principle electrical aging agent and evidence is presented for irreversible loss of polymer as a result of aging. However, the surface recov. ery mechanisms are robust and, provided there is an adequate resting period, the hydrophobic properties recover, This supports the view, from service experience, that there is no substantial evidence to show that normal aging, unless it results in the exposure of the glass fiber core, detracts from the performance of insulators.

134 citations