Effect of Lightning on Electricity

When Lightning Strikes a Transmission Line

Normal lightning

The lightning current flows from the overhead ground wire to the steel tower and then the earth, and no abnormality occurs.

Very strong lightning

The large lightning current greatly increases the steel tower potential, causing the voltage applied to the insulator to exceed the withstand voltage, possibly resulting in a failure.

When a lightning strike (or similar) has occurred, Kansai Transmission and Distribution shuts down the transmission line to prevent a spread of the adverse effects of the high-voltage current. As we instantly switch to another route, the power will not be interrupted, but over an extended power system area centered around the strike location, the power voltage will be subject to a momentary drop (0.07 to 2 seconds). (A short-time voltage reduction is referred to as a momentary voltage drop.)

Lightning Countermeasures

In order to enhance the reliability of our power supply, Kansai Transmission and Distribution is implementing a range of measures within technical and financial feasibility. However, natural phenomena such as lightning, snowfall, heavy winds and rains, as well as unforeseen power system failure caused by flying objects or the like may lead to power outages or momentary voltage drops, which cannot be completely prevented.

Therefore, customers who use electrical equipment that may be damaged by a power outage or momentary power drop are urged to provide suitable means on their premises to guard against such occurrences.

For information on measures that can be taken at home, please refer to “Lightning Strike Countermeasures.”