Faulty high-voltage breaker periodically sidelines Willmar, Minn., turbine
WILLMAR — A faulty high-voltage breaker the size of a small washing machine periodically sidelined one of Willmar Municipal Utilities’ two wind turbines this summer.
The problem surfaced in early June and continued intermittently in July. The City Council asked about the problem during the Aug. 19 meeting.
Utilities General Manager Wesley Hompe described it as a periodic problem. When the breaker didn't work, the turbine didn't work.
“It worked sometimes; it didn't work sometimes,” Hompe told the Utilities Commission on Monday. “It has been kind of frustrating for us as well as the technician (from turbine manufacturer DeWind), especially when you have an intermittent problem as we had, just finding the problem.”
Hompe said he had mentioned in June and July that the utility was having problems finding the specific failure.
When the problem began, the breaker would function normally when the technician was present, but would fail when the technician was one or two hours away and he would have to return to Willmar, explained Hompe. DeWind made multiple visits to Willmar.
DeWind technicians also service other turbines in southwest Minnesota, said Hompe.
It took most of the summer just to force the breaker to fail so at least the technician knew for sure where the problem was, said Hompe.
DeWind ordered a new breaker. Unfortunately, it arrived damaged. The old breaker was re-installed and another replacement was ordered. The second breaker was installed in early August but needed to be certified and tested.
Hompe said the breaker was tested Aug. 23 when an attempt was made to return it to service. The attempt did not go as expected. The technician returned Monday and has been working on integrating the breaker with the entire system.
“The unit will be out of service until he can,” said Hompe.
He said DeWind did a pretty good job of troubleshooting. “But it just was not obvious until later in the summer when they finally determined in fact it was the breaker and they replaced it,” he said.
The turbines were constructed in northeast Willmar just north of the high school and went into service in September 2009. The faulty breaker was in the turbine closest to the high school.
Because of the breaker problem, the turbine's availability to produce energy was reduced from 85 percent in May to 33 percent in June to 22 percent in July, according to the utility's website. Figures for August are not available.
“Availability” measures a generator's potential to produce.
The availability of the north turbine remained high at 99.8 percent in May, 65 percent in June and 84 percent in July.
Commission President Steve Salzer said for the benefit of new commissioners that the warranty with DeWind guarantees reimbursement if availability falls below 95 percent.
Hompe said the commission extended the original two-year purchase warranty by three years. The breaker was covered by the warranty, said Hompe.
Commissioner Joe Gimse asked if extending the warranty again was an option. Hompe said he would have to find out if DeWind was open to another extension.
Commissioner Jeff Nagel asked if there is a government mandate for renewable energy.
Hompe said the Minnesota Legislature passed the rule that requires 25 percent of energy to be provided by renewable resources by 2025.
“The turbines are a piece of that,” said Hompe.