Although more than 100 massive wind wind turbines now turn gently along the hills of upstate New York, erecting those towers required some unusual efforts from electricians. Climbing wind turbine towers on blustery winter days is difficult, but to wire those towers and to stand in the rotating heads of the massive nose cones required what General Electric’s (GE) site manager Ron Homenuk described as “true American grit.” Primary electrical contractor, S & L Electric Inc., Colton, N.Y., displayed that grit.
S & L Electric installed power to all but two of the 121 turbines for plant owner Noble Environmental Power, Essex, Conn., to create the Clinton-Ellenburg Windpark, two sections of turbines built to provide New York Power Authority customers with 181 megawatts (MW) of power. Work extended through the winter of 2007–2008.
The project involved two sites, one in Clinton County in upstate New York, with 67 turbines totaling an output of 100.5 MW, and another in neighboring Ellenburg with 54 more towers and 81 MW of capacity.
The wind turbine generators (WTGs) are GE 1.5-MW towers, which accounted for 45 percent of U.S. commercial wind turbine sales in 2007.
As its name implies, the GE 1.5 MW is rated to supply 1.5 MW of electrical power. However, the conditions and wind speed required to generate a constant 1.5 MW of power from each turbine do not exist 100 percent of the time. Wind levels fluctuate according to the weather, so the actual level of supplied power—the capacity—usually amounts to a varying percentage of full power, most commonly in the 30 to 50 percent range, Homenuk said.
“The capacity of a wind turbine is proportional to the relative wind profile of the geographic area at the installation,” he said. That was the reason Clinton County, known for its windswept hillsides, was a good geographic choice. The steady local winds would provide power that was just as constant.
Noble Environmental Power first reached out to local contractors in the Clinton area. At that time, Leo Villeneuve, S & L Electric company president, walked through the turbines as they were lying on the ground, evaluating the potential task ahead. Noble then awarded S & L Electric the project. Ultimately, S & L Electric obtained three separate contracts. The company contracted two projects with Noble: tower wiring and high-voltage termination. Separately, it contracted with Detroit contractor and construction manager Aristeo Construction for base work.
Although S & L Electric had previously installed a hydropower plant, this was its first wind power plant project. To become familiar with wind power work, S & L Electric’s vice presidents Michael Villeneuve and Rich Menke flew to California to complete a one-week training program in assembling the towers with GE.
They received training in safety procedures as well as high-voltage bus bar installations.
To supplement the local crew, provided by IBEW Local 910, S & L also employed traveling electricians.
The project was intended to be completed by late October and would require workers to connect cable through the three portions of the towers—bottom, center and top—including to the nacelle, which contains the gear box, low- and high-speed shafts, generator, speed controller, and brake. For each tower, the three big blades at the front of the WTG catch the wind and turn a gearbox, Homenuk said, which, in turn, rotates a generator. The generator transmits the power to the base of the tower through cables or bus ducts to a converter.
“The converter does just that: converts via advanced rectification methods. Thus, the sine wave power is converted into a useful DC voltage,” he said. That DC voltage is then inverted to a 575V AC, 60-Hz power output, which is sent to a transformer adjacent to the WTG to be increased to high voltage: 34.5 kV. That voltage is then economically transmitted to a local substation. In this way, the WTG can produce useful power over a wide range of generator RPMs.
S & L Electric ran cable down each tower and did the base work to connect those towers to the substation with 34.5-kV cables.
New heights, new hazards
“The intriguing challenge with wind power is working with the heights,” Menke said. For each tower, S & L had to lower cables from the top of the tower, then attach those cables at the flanges, crimping them together on the way down.
S & L assigned one group of about five electricians to climb to the top of the tower and lower cables. Another crew of four then attached those cables as the members worked their way down the length of the tower. Finally, a base crew handled terminations at the bottom of the tower. On windy days, electricians were not allowed to climb the towers, although winds rarely got too high, Menke said. Instead, the climbing crew members got used to a feeling like riding on a big ship as they swayed with the breezes on top of towers.
The nose cones, where three wind blades attach, also created their own hazard. Each required electrical wiring, for which electricians had to climb into the cone with the brake locked. Although their time in the device took only a few hours, heavy winds occasionally made that work too hazardous to continue.
But it wasn’t the heavy winds that caused delays for electricians as much as it was the cold. As the weather dropped to freezing, the extra gear electricians had to wear to stay warm slowed their progress up each tower and reduced their nimbleness as they worked. What would take two hours in good weather began to take four hours.
“The cold caused delays. It slowed production down as tower climbers had to work their way manually up each tower,” Menke said.
But the conditions didn’t keep many from the project.
“Most electricians chose to stay with the project from beginning to end, which made the process easier because they could use their training,” Menke said. By the time the crew members got familiar with the work, they were able to drop cables from two towers a day and connect the cables on the way down.
At the base of the towers, S & L Electric roughed in conduits and grounding for the tower connections, under the contract with general contractor Aristeo Construction.
All construction projects have challenges, Homenuk said, but wind projects can be very unusual. Just the transportation of the large WTG components to each location can be unnerving, he said, since the blades themselves are more than 120 feet in length.
“Then the tower sections, the machine head [which contains the gearbox and generator] and the three blades attached to a common hub must be lifted to dizzying heights of over 260 feet,” Homenuk said.
Homenuk congratulated S & L workers for climbing up and down the long stretch of vertical ladder on the cold and windy winter days while carrying handfuls of cable.
“Of course, the only way to work on these giant green machines is to climb that 260 feet up a vertical ladder. This type of work is not for the faint of heart nor the out of shape. It is not unusual for a WTG worker to climb three to four WTGs per day,” Homenuk said.
The basic construction was completed in early December 2007. By February 2008, construction crews were “anxiously awaiting the final connection to the local electrical grid,” which would allow them to perform final electrical testing, Homenuk said.
“Following that testing, the WTGs will then quietly fulfill their destiny: producing ecologically friendly power for the next 25 years,” he said.
“Consider the conditions: working over 250 feet in the air, the wind howling outside, having hand-pulled all the required tooling and materials up-tower. And this after having climbed the tower,” he said. “I will say that the quality and commitment of the job performed by the electrical trades at the Noble Clinton and Ellenburg Windparks is impressive,” Homenuk said.
SWEDBERG is a freelance writer based in western Washington. She can be reached at email@example.com.