Being Prepared in the Event of a Lightening Storm 

In our industry, a wind farm is rated by the reliability and consistency at which it generates and provides power to the grid. In order to have the most efficient placement and correct height for optimum wind conditions, wind towers become highly susceptible to weather conditions. With the freedom from ice and cold that summer brings, it is not without its' own challenging weather, such as electrical storms for example. Lightening, whether direct or indirect, can strike the towers causing damage and down time. Some consider wind towers to be large lightning rods and  more susceptible to lightning strikes than other structures of the same height.

That may be true. The science behind lightening hitting a wind turbine helps explain why experts say each wind tower gets struck by lightning once every 12 months at a minimum. When lightning strikes, a negative downward leader moves from the negatively charged storm cloud to the positively charged wind turbine. When contact occurs, current is formed and the bright flash we see is actually the shock wave called the return stroke. Wind turbine blades actually have positive upward leaders that can attract subsequent strikes. The return stroke is the most damaging.

While lightning strikes pose a threat to the equipment, they can also harm the technicians working up tower. Notification timeline is crucial to ensure the safe tower evacuation by all technicians prior to the storm arriving on site. Below are some guidelines to follow in the event weather takes a turn for the worst on site.

• Verify no personnel are permitted in or around a turbine during a lightning storm. During an electric storm, there is a risk of serious injury or death as a result of lightning striking a turbine.

• Sites with lightning advisory system installed at site shall issue a lightning advisory for any lightning strikes within a 30 mile radius. Site manager will alert all technicians/subcontractors of the strike and evacuate the turbines. The advisory shall remain in effect until 30 minutes after the last known strike is reported within the 30 mile radius.

• Sites without a lightning advisory system installed at site shall issue a lightning advisory for any lightning strikes within a 60 mile radius. Site manager will alert all technicians/subcontractors of the strike and evacuate the turbines. The advisory shall remain in effect until 30 minutes after the last known strike is reported.

• All personnel in the field and at the towers need to be prepared to seek cover on short notice. While lightening can still strike a vehicle, it is safer to be in your truck than outside during an electrical storm.

• If lightning activity has stopped but there is still severe weather in the area, the site manager has authority to keep the lightning stand down in effect until he/she feels it is safe to resume normal operation.

The tips above are not all inclusive. Each client has their own lightning protection systems as well as electrical storm procedures specific to their site. It is important to know the operation of the systems as well as any differences in safety procedures at each location. Our technicians are our most important asset, so stay informed and stay safe!