Viscoelastic analysis of cavity propagation in gel with electrical discharge

Quantitative information on the charge and stress profile during partial discharges (PDs) is required in order to discuss and clarify the process of electrical degradation in solids. Such PDs cause cavities to grow. Therefore, we have proposed a procedure for analysing discharges within cavities, ba...

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Bibliographic Details
Published in:Journal of physics. D, Applied physics Applied physics, 2014-04, Vol.47 (15), p.1-8
Main Authors: Sato, Masahiro, Kumada, Akiko, Hidaka, Kunihiko, Yamashiro, Keisuke, Hayase, Yuji, Takano, Tetsumi
Format: Article
Language:English
Subjects:
cavity
Charge
Charge (electric)
Electric charge
Electrodes
gel
Holes
Mathematical analysis
partial discharge
power module
Stresses
Temporal logic
void
Voids
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Summary:Quantitative information on the charge and stress profile during partial discharges (PDs) is required in order to discuss and clarify the process of electrical degradation in solids. Such PDs cause cavities to grow. Therefore, we have proposed a procedure for analysing discharges within cavities, based on motion observation in viscoelastic material. The proposed procedure was applied to surface discharges in silicone gel. Spherical sub-cavities (voids) which form along the cavities were analysed. The temporal response of calculated stress exerted on the void surface depends on the location of the void: whether it is at the tip of the cavity or at the root of the cavity. The results indicated that streamers propagate through the tree structure of the cavity and accumulate electrical charges at the void surface at the tip of the cavity. The temporal response of surface charges had a strong asymmetry according to the polarity of the applied field in contrast to the symmetry of the apparent charge. The amount of charge accumulated in a void was calculated to be approximately 0.1-1%. For voids near the electrode an increase in surface conductivity was observed, whereas voids at the tip of the cavity were non-conductive.
ISSN:0022-3727
1361-6463
DOI:10.1088/0022-3727/47/15/155201