Moog has received a safety certification from TÜV Rheinland for the new Moog Pitch Servo Drive 3. The feathering safety function supplied by the Moog Pitch System 3 Servo Drive alters a wind turbine’s 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 component.
Along with certifying the safety of its new servo drive, Moog improved the architecture of Pitch System 3 to meet IEC 61508 and ISO 13849, standards governing wind turbine safety. First, Moog’s engineers provide a safety function referred to as Safe Feathering Run (SFR), which automatically moves and stops a turbine’s blades in the feathering position. Second, Moog included a Safe Stop function called (STOP1) to arrest the motion of an individual blade during manual movement of the blades. The Safe Stop function meets the ISO 13849 standard that addresses the requirements that blades must not perform an unintended move when people are working inside the wind turbine’s hub. Moog also asked lightning protection company DEHN to test Pitch System 3 (including its servo drive and interface module) inside a high voltage lab subjecting the system to multiple lightning strikes reaching more than 260,000 amps. Afterward, the system was still fully operational and performed a Safe Feathering Run.