Nordex Group has replaced the gearboxes at two N149 Delta 4000 series turbines at Wennerstorf in Lower Saxony, Germany.
The company said the operation on the 4.0-4.5 machines was part of the regular validation and certification process for the hardware.
The turbines have been in operation since August and November 2018 and are the first Delta 4000 units of this model, the company said.
It added that the machines 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 company said.
The aim is to ensure the “theoretically determined reliability” and to incorporate early findings from the operation of the gearboxes into the series production.
In addition, Nordex has obtained information confirming the gearbox design and on optimising maintenance.
It said that 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,” the company said.
The first gearbox was exchanged in February 2020 and the second one in an adjacent turbine was replaced this month as planned.
Nordex said the work was the second time a so-called ‘self-hoisting crane’, which is installed on the turbine’s nacelle, has been used to exchange 4MW-plus gearboxes.