Air-Gap Discharge Characteristics in Foggy Conditions Relevant to Lightning Shielding of Transmission Lines

• Published in: IEEE transactions on power delivery Vol. 23; no. 4; pp. 2409 - 2416
• Main Authors: Taniguchi, S., Okabe, S., Takahashi, T., Shindo, T.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Air gaps; Applied sciences; Conductors; Connection and protection apparatus; Discharge; Discharge characteristics; Drying; Electrical engineering. Electrical power engineering; Electrogeometric models; Exact sciences and technology; Fault location; Fog; foggy conditions; Lightning; lightning shielding; Mountains; Power transmission lines; Shielding; Testing; Transmission line theory; Transmission lines; ultra-high voltage (UHV)-designed transmission lines; Voltage; Wires; Performance evaluation; Ultrahigh voltage; Discharge characteristics; ultra-high voltage (UHV)-designed transmission lines; Lightning protection; Protective device; Shielding; Electromagnetic shielding; lightning shielding; Scale model; Damage prevention; Geometrical model; foggy conditions; Lightning discharge; Transmission line; High voltage; Lightning; Air gap
• ISSN: 0885-8977; 1937-4208
• DOI: 10.1109/TPWRD.2008.2002870

The features of lightning shielding of transmission lines have been calculated using the electrogeometric model (EGM) proposed by Armstrong and Whitehead. Discrepancies, however, have been found in the case of ultra-high voltage (UHV)-designed transmission lines. UHV-designed transmission lines often pass through high-altitude mountain areas, where foggy or rainy conditions are common when there is lightning. While the electrogeometric model determines the striking distance based on the lightning stroke current, environmental conditions, and how they might affect lightning discharge paths, they are not considered. It is possible, therefore, that foggy conditions may cause differences in the performance of transmission-line lightning shielding. This study used scale models of transmission lines for discharge tests with a 1-m air gap and analyzed differences in discharge paths and locations in dry and foggy conditions. The results showed that the polarity of the discharge had a significant influence, but differences in dry and foggy tests were negligible.