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Title: Effect of some of climatic conditions in the performance of outdoor HV silicone rubber insulators
Author: Nekeb, Abdelbaset
ISNI:       0000 0004 5346 6859
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2014
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Silicone rubber (SiR) insulators are increasingly being used mainly because of their superior performance under wet polluted conditions compared to conventional porcelain and glass. However, in polluted environments with high moisture levels, electrical discharges will develop on the insulator surfaces. In the long term, electrical discharges cause degradation of SiR insulator in the form of tracking and erosion due to dry-band arcing that takes place when leakage current (LC) develops, and both are detrimental to the life of the insulation. This thesis presents an experimental study on the electric performance of aged high voltage outdoor silicone rubber insulators. In addition to the literature reviewed of the performance of silicone rubber insulators subjected to different climatic conditions, which is resulting in loss of their unique property named ‘hydrophobicity’, the research is concentrated in three areas: (i) Study of the effect of ultraviolet (UV) irradiation on the performance of silicone rubber insulation systems: 11kV non-textured and 4mm Textured Shank insulators (TS4) (TS4 is a new insulator design using intersection of 4mm square texture pattern on the shank regions of the insulator) were prepared in vacuum casting machine. Irradiated insulators were tested under different conditions. Dry-band formation and electrical discharges on their surfaces are dependent on the UV doses. Degradation of SiR insulators in a form of tracking and erosion is result in loss the surface hydrophobicity by UV irradiation, and decrease of the expected life of the insulators. Silicone rubber insulator electric performance was found to be affected by the experimental conditions. LC on relatively hydrophobic surfaces was found to exist and increase on overall insulators with increasing the exposure doses of UV irradiation, by increase the number of applied UV cycles. (ii) Development a new test set-up to determine the effectiveness of orientation angle on the performance of silicone rubber insulators subjected to different wet and pollution conditions: LC of silicone rubber insulators were increased with changes in the orientation angle from vertical to horizontal, where the TS4 showed its superior performance under fog conditions in the vertical orientation. (iii) A new test procedure, based on the high voltage ramp test method and standard wet test method, named ‘high voltage rain ramp test’, is proposed to evaluate the flashover performance of the TS4 silicone rubber insulators under simulated rain conditions at different orientations. Its flashover performance was compared with non-textured insulators. TS4 silicone rubber insulators are less suitable for wet weather conditions in any orientation, due to the following reasons: (a) in vertical orientation a very low flashover voltage was observed due to the development of high magnitude electric fields in the insulator shank region, and (b) for the inclined and horizontal orientations, non-textured insulators exhibit a better flashover performance than their textured equivalents. Hence, less improvement is achieved, due to use an expensive and intricate insulator design.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TA Engineering (General). Civil engineering (General) ; TK Electrical engineering. Electronics Nuclear engineering