Effects of Surge Protective Devices on Overhead Power Line Induced Voltage From Natural Lightning

Voltages induced on a 1300-m overhead power line by 51 return strokes in a thunderstorm process in Guangzhou Field Experiment Site during the summer of 2008 have been measured. As to a group of surge protective devices (SPDs) were installed at the end of the overhead power line, the peak values of induced voltages were all below 1 kV, and most of induced voltage waveforms show typical residual voltages. The interval time of adjacent return strokes ranged from 14.0 to 185.6 ms. The peak values of induced voltages at the SPD site were obviously under attenuation compared to that at the household site. The lightning location data indicate that the induced voltage might be of either positive or of negative polarity depending on the location of the lightning strike points. The peak value of induced voltage tends to saturate when the ratio of peak value of return stroke current to distance from the stroke location to the measuring point exceeds 4 kA/km.