Patent ID: 8212583

Claim:
A method for ground testing a yaw system for driving a nacelle of a wind turbine prior to mounting the nacelle on a tower, the ground testing to determine whether the yaw system is operational, the ground testing comprising the following steps: (a) connecting a portable transformer device to a generator for supplying voltage on the ground, the generator having a first output voltage provided by a first output voltage connection, wherein an input voltage connection of the portable transformer device is connected to the first output voltage connection of the generator, and wherein the portable transformer device provides a second output voltage by a second output voltage connection equal to the first output voltage of the generator and a third stepped down output voltage by a third stepped down output voltage connection; (b) connecting the second output voltage connection of the portable transformer device and the third stepped down output voltage connection to the nacelle of the wind turbine; (c) connecting a controller to the nacelle for controlling a yaw system of the nacelle; (d) powering on the generator to provide the first output voltage from the generator; (e) receiving by the portable transformer device the first output voltage from the generator, providing the first output voltage of the generator to the second output voltage connection and stepping down the first output voltage from the generator to provide the third stepped down output voltage connection to the nacelle of the wind turbine; (f) energizing the yaw system, such that the yaw system receives the second output voltage and the third stepped down output voltage from the portable transformer device; and (g) outputting an indication to status lights of the yaw system to indicate that the yaw system is operational in view of movement thereof, the testing performed prior to mounting the nacelle on the tower.