Study on DC Pollution Flashover Performance of Various Types of Long String Insulators Under Low Atmospheric Pressure Conditions

• Published in: IEEE transactions on power delivery Vol. 25; no. 4; pp. 2132 - 2142
• Main Authors: Zhang, Zhijin, Jiang, Xinliang, Chao, Yafeng, Chen, Ling, Sun, Caixin, Hu, Jianlin
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Air pollution; Applied sciences; Atmospheric modeling; Atmospheric pressure; Connection and protection apparatus; Direct current; Electric potential; Electrical engineering. Electrical power engineering; Electrical power engineering; Exact sciences and technology; external insulation; Flashover; flashover performance; HVDC transmission; insulator string; Insulators; low air pressure; Materials; Miscellaneous; Pollution; Pollution abatement; Power networks and lines; Strings; Surface contamination; Various equipment and components; Voltage; Voltage control; Performance evaluation; Insulator; Atmospheric pressure; Dielectric materials; External insulation; pollution; Electric circuit; Electric discharge; Composite material; flashover performance; Porcelain; Electrical network; low air pressure; Physical model; Low pressure; High speed; Electrical flashover; Air gap; insulator string; Air pollution; Series resistance; Arc length; Electrical characteristic; DC
• ISSN: 0885-8977; 1937-4208
• DOI: 10.1109/TPWRD.2010.2049132

In this paper, the dc pollution flashover performance of various types of porcelain, glass, and composite insulators is investigated. It also presents analysis of the dc flashover process of polluted insulator string at high altitude using insight from high-speed photography. The research results indicate that the relationship between the dc pollution flashover voltage and the string length of insulators is basically linear, the characteristic exponents describing the influence degree of air pressure on pollution flashover voltage vary between 0.35 and 0.77 and are related to the insulator types and pollution degree, etc., the characteristic exponents describing the influence degree of pollution on flashover voltage vary between 0.24 and 0.36 and are related to the insulator types and air pressure, etc. Based on the flashover phenomena using the insight from high-speed photography, a new physical model explaining the flashover mechanism for a polluted insulator string at high altitude is introduced, which can be expressed as an electrical circuit consisting of a surface arc of length x 1 and air-gap arc of length x 2 in series with a resistance representing the wet pollution layer. In addition, the exponent n describing the influence degree of air pressure on flashover voltage for the polluted insulator is discussed.