Abstract
To evaluate the V-t characteristics of uniform-field air spark gap, which are important in designing insulation of distribution lines against steep-front surge voltage, a method of calculating the formative time lag has been established for arrester series gaps and protective gaps in the case of short gaps ranging from 0.1 to 0.7 cm. Results of the calculation are compared with experimental ones with a close agreement between the two for the formative time lag ranging from 0.06 to 1 μs. In the case of 0.1cm gap length, however, there is some difference between the two. By discussing relations between p.d and Δ, where p, d and Δ are the barometric pressure, gap length and percentage overvoltage, another method is developed for calculating the formative time lag in the range of gap length of 0.1cm or less. In addition, with regard to longer gap ranges in the case of air insulation, the compatibility of the established method has been examined to confirm a close agreement of the calculated values with the experimental ones in the case of 6cm gap length.
