A blade detached from a turbine at the site before falling into a field on 11 February, MidAmerican confirmed.
MidAmerican Energy, which owns the 250MW project, added that nobody was hurt during the incident and that it had paused "fewer than two dozen" turbines at Lundgren and "other sites" to gather more information. It has since placed most of these turbines back online after carrying out safety checks.
It plans to return the four remaining turbines to service "soon", pending safety inspections, MidAmerican added. It is unclear whether these four turbines are at Lundgren, or at other wind farms.
The company stated: "MidAmerican is working with the manufacturer, Siemens Gamesa Renewable Energy, to conduct a full investigation to determine the root cause of this incident. While incidents like this are very rare, they are nonetheless something that we take very seriously.”
The 250MW Lundgren (Wind VIII) Lundgren (Wind VIII) (250MW) OnshoreWebster County, Iowa, USA, North America Click to see full details wind farm is located in Webster County, Iowa. It was developed by EDF Renewables and came online in 2014.
The project uses 108 of Siemens Gamesa's SWT 2.3MW-108 turbines according to Windpower Intelligence, the research and data division of Windpower Monthly. Siemens Gamesa has been approached for comment.
The apparent malfunction at the wind farm follows a turbine collapse at the 54MW Butler Ridge Butler Ridge (54MW) OnshoreMayville, Wisconsin, USA, North America Click to see full details wind farm in Dodge County, Wisconsin last month.