Effect of Predischarge Currents Upon Line Performance

The magnitude of predischarge currents of gaps under impulse conditions have been determined. For gaps formed by two parallel pipes the magnitude is found to be approximately proportional to the length and to the spacing. These currents, which must be drawn through the impedance of the line, produce drops at 2 or 3sμsec (microseconds) that may be equal to or greater than the gap voltage. Adaptation of these properties improves the lightning performance of transmission lines.