Lightning strike is a very short event. The current pulse takes several hundred microseconds. This order of duration is not enough for a fly to swing its wings even once. The lightning protection grounding arrangement should dissipate the lightning energy very rapidly. In such conditions, the grounding electrode capabilities strongly differ compared to "slow" 50 Hz industrial currents.
In order to evaluate the pulse parameters of the grounding arrangement, its current spreading resistance with a wave characteristic of a similar lightning is measured. Here, the difficulties occur which provide for the measurement error of several dozens per cent.
Read a special article by Prof. Eduard M. Bazelyan to learn how the return line of the pulse generator and the electromagnetic interference affect measurements as well as the results of experimental field testing.
E.M. Bazelyan, Dr. Sc. (Eng.), Professor;
Krzhizhanovsky Energy Institute, Moscow;
renowned Russian Expert in Grounding and Lightning Protection