Precisely this type of Fuhrländer turbine, where the rotor is connected directly to the gearbox via the main bearing, requires the high degree of specialist knowledge that Alpiq Wind Services has gained with the support of Enertrag Service GmbH. Besides servicing and maintenance works, the portfolio also includes inspections such as gearbox endoscopies, rotor blade inspections and repairs. “The first indication of the problems with the two main bearings came from the Condition Monitoring System – CMS for short. It uses special sensors to monitor conditional changes in the gearbox, generator and main bearing. Subsequently, regular inspections within a period of one year repeatedly found metal particles in the main bearing siphons, which made exchanges unavoidable. An exchange like this is no small project: stop the facility, dismantle the rotor, exchange the bearings, reassemble the rotor, carry out test runs, and so on... In all, it takes somewhere between 9 to 15 days to exchange a main bearing”, says Torsten Reusch; and this is only for the implementation.
A serious balancing act
Planning begins long before the main bearing is exchanged. A 600 t crawler crane must be arranged, employees must be organised and the replacement parts must be sourced. When the crane is dangling the 63-ton rotor in the air, it becomes clear that the right weather conditions are also required. Because of the risk of tilting, work like this can only be carried out in wind speeds of maximum 6-7m/s. “So far, we are confident that we can stay on track. Our extensive experience will help us with that. In the last seven years, we have exchanged no less than 16 bearings just like this one”, says Torsten Reusch, and he reflects on previous successfully completed installation works.