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Effect of field utilization factor on air breakdown level under lightning impulse

Yusoff, Noor Ain (2015) Effect of field utilization factor on air breakdown level under lightning impulse. Masters thesis, Universiti Tun Hussein Onn Malaysia.

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Abstract

The goal of this project is to develop a relationship between field utilization factor (ɳ) and air breakdown level under lightning test. Standard lightning impulse of 1.2/50 is used in this study, along with three difference electrode configurations (rod-rod electrode, rod-sphere electrode and sphere-sphere electrode) with variable gap lengths. In addition, the lightning impulse breakdown level considering utilization factors are studied for the establishment of insulation design criteria of high voltage power equipment. The utilization factors are represented as the ratio of minimum electric field (Emin) to maximum electric filed (Emax). COMSOL software is used to develop electrode model in order to analyses the electric field. It was found that higher gap lengths provide higher U50 for a given electrode configuration, although the rise in U50 is more clearly in sphere-sphere electrode configuration. Where, sphere-sphere electrode configuration require higher U50 to breakdown it is 40% than rod-sphere electrode configuration (30%) and rod-rod electrode configuration (28%), respectively. A difference in Emax values where the higher gap length provide lower Emax for sphere-sphere electrode configuration, while the higher gap length provide higher Emax for rod-rod and rod-sphere electrode configurations. Considering the effects of field utilization factor, which was based on difference electrode configurations, it was found that sphere-sphere electrode more uniformity at gap length 0.5 cm (0.9968) than rod-rod electrode at gap length 1 cm (0.2057) and rod-sphere electrode at gap length 1 cm (0.1546). Where the values of each field utilization factor (ɳ) is 1 in the uniform field and 0<ɳ<1 is in the non-uniform. Furthermore, it can be concluded that electrode configuration, which includes electrode geometry and gap length, plays a big role in determining U50 values for air breakdown level in order affected to uniformity in field utilization factor (ɳ) values.

Item Type: Thesis (Masters)
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK2000-2891 Dynamoelectric machinery and auxiliaries
Depositing User: Mrs Hasliza Hamdan
Date Deposited: 04 May 2016 09:54
Last Modified: 04 May 2016 09:54
URI: http://eprints.uthm.edu.my/id/eprint/7794
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