Slip Rings in Off-Shore Wind Turbines
Standard wind turbines have proven to be a harsh and rugged environment for electrical slip rings. However designing slip rings for off-shore wind turbines is an even tougher challenge. Not only are we dealing with gearbox oil, dirt and vibrations, but now we are aslo exposed to salt water and salt air.
The salt environment can cause a few different problems for a slip ring if not properly designed. First of all, the outer housing and hardware must be suited for slat air. Even if a rusty enclosure and screws don't change the performance of the slip ring, no turbine manufacture wants to install a rusty component on a multimillion dollar machine. United Equipment Accessories uses all stainless steel hardware if possible which also makes maintenance much easier. As for the housing, aluminum is generally used among all slip ring suppliers as it is durable and light weight, but it’s not the most corrosion resistant material. Because of this, UEA has standardized to have aluminum components anodized if being used in a salt air environment.
No matter how well a slip ring enclosure is sealed it seems the salt air still finds it way inside. This can cause brass rings to corrode at a much more accelerated rate. The biggest challenge is to keep the rings from starting to corrode before they are put to use. A lot of the slip rings will sit for months before they are actually being used. If they are sitting in a salt environment, some type of protection is needed. UEA uses a type of electrical protection spray that coats the rings and stops them from corroding, but the biggest benefit that UEA offers over most competitors is the self cleaning brushes. We run a very high brush pressure compared to most manufactures, so if some corrosion on the ring does occur, the brushes will clean the rings as they begin to rotate.
These are just a couple of the issues that we take into consideration when designing slip rings for the off-shore environment. As the wind industry progresses I have a feeling we will be seeing a lot more of these applications.
-Jesse Shearer, Design Engineer