Presentation Description: Testing was performed on two typical wind turbine main shaft bearing greases. The tests were used to compare the performance of these greases in conditions that simulate up-tower operation. Previously, Pierman [1], Mistry [2] compared nearly a dozen wind energy greases by examining them with standard lab tests to identify greases that may perform best under various field conditions. Two of these greases, which are well known in the industry, were then selected as the subject of this paper for a more detailed investigation. Three new tests were performed to evaluate: film thickness, bearing life, and torque and temperature. The torque and temperature were measured using a full-size, preloaded 2MW direct drive wind main shaft bearing operated at typical operating speeds. The results of these tests summarized in this report were surprising as viscosity alone did not dictate the expected results.
Learning Objectives:
better understand two grease performance options currently available used in wind main shaft bearings.
gain knowledge related to grease parameters which influence the bearing life and temperature.
understand that theoretical predicted bearing life calculations and actual bearing lives may be different. For some greases, the actual bearing life will be significantly better than predicted by analytical calculations. Improvements in grease models are needed to include the impacts of the grease additives and thickeners on the predicted bearing lives.
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