Health & Safety

While the incident rate of arc flash may be low in the wind sector, the results can prove costly for operators and possibly fatal for technicians. What is the best preventative strategy for wind farm operators to adopt?

By Bob Moser, Americas correspondent

In April, a Minnesota-based wind-power firm was hit with US$378,000 in OSHA penalties when a worker suffered third-degree burns from an arc flash. With OSHA likely to tighten safety enforcement in the wind sector in coming years, turbine operators are advised to keep a step ahead on preventative safety measures.

Health and safety requirements already in place are being enforced more stringently this year by the Occupational Safety & Health Administration, or OSHA. Wind farm operators must comply with OSHA’s §1926 safety standards during construction, and afterward §1910 standards when the turbines are operational.

There are also national consensus standards for the industry specifically focused on arc flash issues – NFPA70E – which all AWEA members follow. Turbine owner-operators must have detailed emergency response programs prepared in case of an accident, and relationships should be built with local emergency response units.

Robust data needed

As the US wind energy sector continues to grow, and with regulators upping their oversight of this nascent industry, turbine operators and maintenance firms are now, more than ever, buying in to the value of good training, progressive safety equipment and niche accident data.

However, despite the US Bureau of Labor Statistics collecting a wealth of data each year on workplace accidents, it has yet to create a category specific to the wind energy industry. Currently it bundles wind sector statistics into a category for “energy generation” with statistics from a broad range of industries. Consequently, operators do not yet have access to robust data on the frequency of arc flash incidents in the wind industry.

Last year, in an effort to refine data on health and safety within the sector, the American Wind Energy Association created an anonymous survey in which wind energy companies could participate. The survey's first round closed in June. Michele Myers Mihelic, AWEA's health and safety manager, says that so far AWEA has received between 40 and 50 detailed responses from companies.

Preventative strategy
For their part, operators themselves are taking a proactive stance. WindIngen, a Colorado-based maintenance contractor, puts its technicians through OSHA-mandated safety training, and endorses the use of protective helmets and full-body clothing for technicians to protect against arc flash.

“We've had the extensive training and seen the photos shown for arc flash. Those will definitely get your attention,” said Anthony McNeill, general manager. “All our clothes are FR-rated (flame resistant), which I'd recommend, meaning they offer some protection from arc flash. A face shield and gloves are important to use as well.”

Many engineering firms now provide arc flash hazard analysis, helping turbine owners foresee weak spots in their network. Analysts map how many feet of cable lie between each tower, how much power passes at any given time, and create scenarios that would force short circuits on the farm.

They want to forecast how much incident energy will be generated when an arc flash occurs, so owners can limit the burst to acceptable levels. Analysts will also generate labels to apply on turbine equipment throughout the farm, showing technicians how much incident energy may occur at each point. This helps determine what level of flame-resistant clothing is needed to safely work on that piece of equipment.

Safety gear and supplementary equipment are readily available to turbine operators to help reduce the risk of power overloads and arc flash. Switchgear that is arc flash-resistant is available that has a “weak wall” built in, blowing out at the moment of an overload to deflect the arc flash away from the person working on the turbine.

Arc flash electric sensors are available for switchgear that have special relays in place to sense an arc flash, and disable the power unit instantly before the burst of energy arrives. Remote control devices are also available for technicians to operate switchgear anywhere from 20 to 60 feet away.

No substitute for experience

Regardless of any new clothing or smarter sensors the market develops, inexperienced technicians will always be the biggest risk for arc flash and other power-related accidents, says John Kolak, president of Praxis Corporation, an electrical safety consulting firm.

If a technician is poorly trained and tested, they can often make the mistake of resetting circuit breakers on a turbine before testing it first, which can result in explosions, Kolak said. Another dangerous error he has seen in past field visits is the misuse of volt meters by workers examining a turbine's electrical system, which can directly result in an arc flash.

“The typical mistake made by inexperienced technicians is to inserts the leads from the meter into the wrong terminals on the face of the meter,” Kolak said. “This results in a short-circuit through the meter when the technician attempts to take a voltage reading.”

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