The field research of voltages and currents in actual distribution lines done by the Tokyo Electric Power Company confirm that the distribution line faults are mainly caused by direct lightning strokes to the line. This necessitates the need for a lightning protection design of distribution lines. Here, the observed voltages and currents are analyzed in terms of the statistical data. a lightning surge analysis model is used for the purpose.
Many lightning protection devices such as shielding wires and surge arresters are used by many electric power companies in order to reduce the distribution line faults. The lightning outages have reduced considerably with the use of the above countermeasures.

OUTLINE OF OBSERVATION SYSTEM.
Observation Sites
The Kanto plain in Japan is used as the observation site for the study.

Camera for Lightning Channel
The external lightning intensity controls the shutter of a camera. Two or more images are taken of the lightning strike. The intersection point of the directions of each camera on the map give the lightning striking location

Equipment for Lightning Surge Waveform
Two devices were used for this purpose:
- a current-measuring sensor with a Rogowskii coil and
- a voltage-measuring sensor consisting of a capacity-type potential divider with a light-sensing device

get the report pdf here:
http://goo.gl/iuVIv