Lightning protection measures for the Mogami transmission test line

The Mogami transmission test line is intended to study oscillation (mainly galloping) prevention measures for overhead transmission lines. It is located near the Sea of Japan, in an area well known for its frequent winter lightning strikes. Two 35 m high steel towers were constructed in 1979, and a further three 47 m high towers were added in 1994. However, the observation equipment experienced damage in the years following construction. Finally, the facility was badly damaged by lightning during the spring and summer of 1997. The damage was caused mainly by electrical shortages in equipment, resulting in huge restoration costs for work that took two months to complete. However, the lightning prevention measures that were added to the facility after the damage in 1997 have served to greatly lessen the chance of further damage by lightning. This paper presents the measures taken to prevent further damage from lightning strikes after the damage of 1997 and the more advanced lightning protection measures for UHV steel towers.