Preliminary Study of Impulse Grounding Impedance Detection for Towers of Transmission Line

Abstract

Lots of operation and maintenance results show that detection of the power frequency grounding resistance of transmission towers is not enough to ensure its lightning protection performance for transmission lines, which means the characteristic of grounding device under the lightning stoke should be discovered. To obtain impulse grounding impedance (IGI) characteristics for the grounding device of transmission tower, a portable miniaturized instrument was designed and developed. It can output the 8/20 µs standard lightning currents with simultaneous measurement of the response transient voltage wave shapes, then the corresponding IGI can be calculated with the wave shapes of current and voltage. Tests were made to 10kV transmission towers in the field, while the analyze results show that the instrument is convenient and practical for use, the testing method is simple to application and the test results can accurately reflect the basic physical properties of the grounding device of 10kV transmission towers.