WILLMAR -- A crew from Electrical Maintenance Service of Gary, S.D., was in Willmar on Monday to investigate a problem that cropped up Friday in the power unit atop one of the Municipal Utilities' two wind turbines, the Municipal Utilities Commission was informed Monday.
Commission members asked why the turbine was not operating.
Wes Hompe, utilities' staff electrical engineer, said a sensor in the nacelle (the power unit on top of the tower) indicated the north turbine had a low-oil problem in the gear boxes and the hydraulic system.
The two turbines were built this year in a nearly $10 million project and will provide enough power to supply about 3 percent of Willmar annual electricity needs.
Hompe said the oil problem may be related to a faulty sensor or a sensor that is incorrectly plugged in.
"If you have a low oil indication, odds are you don't have an oil leak. You're not burning oil. You probably have a bad sensor and that's what happens when things are running for a while. It all gets warmed up and then you find out how things are going to work,'' he said.
Hompe said the turbines are complicated machines and problems cannot be predicted.
He said EMS is under contract from DeWind, which made the nacelles in Round Rock, Texas. Hompe said EMS works on turbines made by DeWind and other turbine brands located throughout southwest Minnesota. Hompe said EMS will remain on site until the problem is repaired or order new parts and replace those later.
Commissioner Gary Myhre asked when the warranty period begins.
Hompe said the 24-month warranty period will begin when Willmar accepts the turbines as totally and finally complete, but he said the repair is essentially being performed before the warranty period begins.
Hompe said utility power plant workers will be trained to perform maintenance after the warranty period expires. He said they're receiving on-the-job training while the warranty work is being performed, and they'll attend formalized training from Electrical Maintenance Service.
The two turbines sit just north of Willmar High School and were built on land leased from the Willmar School District.
The south turbine is also slated for some repair work. A couple of "dings'' were detected on two of the three Fiberglas blades. The 131-foot blades were made in Germany and shipped by truck from Houston, Texas, to Willmar.
The blades received a temporary repair this summer and permanent repairs are anticipated next week. The damaged blades will be locked in the down position and a crew will be suspended by a crane in a man basket. The repair will take a couple of days to complete.
Otherwise, the turbines have been running just fine, Hompe said.
"We've been getting some good power out of them. This last weekend was a very good wind-producing weekend,'' he said. "Too windy is 55 mph over 10 minutes. We haven't approached too windy yet -- not a gust of 66 mph like we had. That is survivable. They're designed for that.''
In other business, Bruce Gomm, general manager, said the No. 2 power plant turbine is operating again after it received extensive repairs this year. He said the 7.5-megawatt turbine was given a performance test two weeks ago and plant workers found efficiency had increased at least 10 percent.
Gomm also reported discussion is underway on a couple of items in the contract with Monson Excavating of Willmar, which was the wind turbine general contractor. Gomm declined to discuss specifics during the open meeting, but said he is working with City Attorney Rich Ronning on the items.
Monson built the roads to the turbine site, poured the foundations and erected the units through a variety of subcontractors.