The facility in west Yorkshire, northern England, will allow full-load testing to be carried out in the UK for the first time.
Moventas' facility upgrade is expected to be completed by July.
It means gearboxes no longer need to be shipped to Europe for testing after servicing, Moventas said.
The firm said it is able to service 60 models of turbines across 20 brands, including Vestas, Nordex, Senvion and Siemens.
The site of the test rig in Huddersfield was acquired by Moventas when it bought the wind business from David Brown Engineering in September 2013.