A testing research on the effect of conductive backfill on reducing grounding resistance under lightning

An outdoor field testing is carried out to research on the effect of conductive backfill on reducing the impulse grounding resistance. The question whether and why the effect under lightning condition is different from that under power frequency condition is concerned. Based on the testing results, the effect of conductive backfill under lightning condition is compared with that under power frequency condition. It is concluded that ionization is also an important factor besides resistivity that affect the effect of reducing grounding resistance under lightning condition. But the effect of the conductive backfill on reducing the grounding resistance under lightning condition is hard to compare with that under power frequency condition quantitatively.