Measurement of Lightning-Induced Voltage on Test Distribution Line Near Tall Structure

Abstract

Lightning-induced voltages on a test distribution line had been observed near the Fukui steam power plant since 1980. From 1993 the observation was resumed on a new test line at 370m from the 200m stack of the plant. Measured induced voltage waveforms showed the characteristics of those influenced by finite ground conductivity, estimated to be higher than 10mS/m. Measured horizontal electric field waveforms were composed of narrow pulses having the duration of less than 5μs and of slowly varying components having the duration of more than 50μs. The narrow pulses were generated due to the finite ground conductivity after the onset of a large current pulse. The slow component, observed during the leader process as well as after the onset of a large current pulse, little contributed to generation of induced voltages. Some of the measured horizontal electric field waveforms associated with lightning strokes to the stack were bipolar in the submicrosecond range. This type of a field change can be attributed to the reflection and the refraction of lightning current waves at the top and the bottom of the stack.