Presented by Ben Clark, RESA Power Service

Wind Farms are becoming one of the most prevalent signs of green energy along transmission corridors. With the open pastures of green energy and associated testing, NETA firms and Electrical Contractors are tasked with overcoming unique requirements. With unique requirements, there also unique opportunities to service customers during and after site commissioning. Each feeder line daisy chains from wind turbine to wind turbine, miles apart from each other. So, a failure upstream on that feeder causes significant downtime for the entire string of turbines. Wind farms utilize millions of miles of cables as well as thousands of joints, splices, terminations, and bolted connections. Each one of these are potential failure points and have a specific test criterion for both commissioning and maintenance intervals. This case study revolves around wind turbine transformers and bushing failures. This particularly case occurred when wind turbine (WT) transformers were energized after commissioning at a wind farm and several bushings failed on various sister units in less than a year. As is typical with Wind Farms, the WT transformers were all from the same manufacturer. The case study required owner coordination, testing, root cause analysis and findings.