The Moog Pitch Servo Drive, a component of Moog’s Pitch System responsible for guaranteeing the safe operation of wind turbines, obtained TÜV certification for compliance with the guideline issued by Germanischer Lloyd. This validates that Moog designs achieve Performance Level D for the wind turbine feathering safety function. Moog is one of the first companies to obtain this certification for AC Electric Pitch Systems.
 
The safety of wind turbines is governed by a number of competing standards and requirements including the ISO 13849-1 standard, which is referenced as a suitable functional safety standard in the GL2010 guideline. This guideline recommends Performance Level D as an appropriate safety level for the feathering of a turbine. The feathering safety function alters the blade pitch at the rotor hub to minimize the torque applied by the wind, avoiding excessive speed of the turbine. As a result, the pitch servo drive is classified as a safety-critical component. The mechanical sizing and load calculations of three-bladed wind turbines are such that it is sufficient for two of the three blades to move to the feathering position.
 
The TÜV Rheinland certificate qualifies that the Moog Pitch Servo Drives (i.e., Pitchmaster II and Pitchmaster II+ models) provide the necessary hardware and software for Performance Level D for the feathering safety function in a two out of three redundancy configuration.
 
Until now, no safety functions conforming to ISO 13849-1 have been implemented in wind turbines for AC pitch systems. This is partly because conformance may require significant changes to turbine components and systems.
 
“The lack of clarity on the requirements is a big challenge for component suppliers and turbine manufacturers as well as for the certification bodies in the design and approval process of new wind turbines,” says Matthias Pauli, core components manager for Moog.
 
Moog Inc. 
www.moog.com/wind