Current instability and chopping with arcs in series

Static modelling of AC flashover on contaminated insulators covered with ice using intelligent identificat ion methods =

“…The results of these methods (referred to as analytical arc models) have provided the theoretical basis for the investigations carried out on designing power system apparatuses such as high voltage breakers [3,68], as well as the dynamic modeling of insulators' flashover under various atmospheric conditions [16,101,60,4,35].…”

“…The equation (2)(3) implies that the arc voltage gradient is constant across arc length so that the arc voltage is calculated by multiplying the E arc with the arc length x. The arc constants A and n were determined by several researchers in the ranges of and [0.…”

“…In this model, arc channel is assumed to be cylindrical with a constant diameter where the arc channel loses its energy by radial heat transfer, which can be expressed as an approximation of Saha's solution for the general arc equation given by (2)(3)(4). By considering this assumption accompanied with the substitution of a constant power loss of the arc per unit length channel into its general equation (2)(3)(4), the following equation for analyzing the arc conductance was attained:…”

“…the formulas for calculating the resistance R p of the polluted layer were derived as given by equations (2)(3)(4)(5)(6)(7)(8) and (2-9) for narrow and wide strips, respectively, and the factor which takes into account the change in resistance due to heat is presented as well.…”

“…The maximum velocities reach about 100 m/s and 50 m/s for outer and inner arcs respectively, just before flashover [28]. The radius of both inner and outer arc is proportional to the square root of the leakage currents as given by equations (3-12) through (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Under AC conditions and for rectangular ice samples, the partial arc on ice surfaces extinguishes and reignites with the cyclical variation of the applied…”