As part of the regular validation and certification process for its turbines in the Delta4000 series, the Nordex Group has replaced the gearboxes first installed in two N149/4.0-4.5 turbines in Wennerstorf, Lower Saxony, Germany. The turbines installed at this site in 2018 are the world’s first Delta4000 turbines of this model.
The turbines have been in operation since August and November 2018 respectively and are subjected to a detailed assessment of their condition after the first 15 and 24 months of operation. To this end, the manufacturer expertly dismantles the gearboxes into all individual parts in order to perform a qualified assessment with the bearing manufacturers and Nordex experts. The aim is to ensure the theoretically determined reliability and to incorporate early findings from the operation of the gearboxes into the series production and the further development of wind turbines with more than 4MW rated power. In addition to this, the Nordex Group obtains relevant information confirming the gearbox design and on optimising maintenance. The drive train is designed in such a way that gearboxes from different manufacturers can be installed. These planned gearbox exchanges give the Nordex Group an opportunity to install gearboxes from different manufacturers and to test and compare their behaviour and efficiency in real operation.
In the Wennerstorf wind farm the first turbine gearbox was exchanged in February 2020 and the second one in an adjacent turbine was now replaced in September as planned.
It was the second time a so-called “self-hoisting crane (SHC)”, which is installed on the turbine’s nacelle, has been used to exchange 4 MW+ gearboxes. This self-hoisting crane climbs up the turbine tower on its own hoist rope and installs itself on the topside of the nacelle. This means that it can be rapidly mobilised, requires little space on the ground and is less expensive to use. This solution has an advantage over conventional cranes, especially in remote regions, for turbines with very high towers or in countries where crane costs are generally high.