The cause of Tana Substation fire accident in July 2001 and its countermeasures

• The cause of Tana Substation fire accident and countermeasures (in Japanese), Hot Hot Tokyu 12/2001, Tokyu Corp..
  (http://www.tokyu-group.co.jp/hot/pdf/2001-12_2.pdf)

In July 2001, a fire broke out at Tana Substation serving Tokyu Railway's Den'en-toshi Line, after it was damaged by a lightning. This document is a technically interesting record of what has happened, and the countermeasures they will take to prevent similar incidents in the future. The root cause is that, since the equipment was individually earthed, the difference of earth potential became too high when the lightning impulse came in, which damaged some of the equipment. Subsequent reclosure at the other substations caused the electric arc over the damaged part, which resulted in the break-out of fire. This will be an example of the fact that protecting the electric railway system, which uses relatively low voltage, against lightning impulse is not an easy task.