Condition-based maintenance on wind turbines not only involves maintenance, but also encompasses servicing, inspection, measurement and evaluation of the current condition of the unit. As a condition-based maintenance tool, Condition Monitoring is a component of long-term service packages offered by some wind turbine vendors and essential for operating offshore wind farms. Several thousand wind turbines are presently equipped with Condition Monitoring systems (CMSs). CMSs record the running and operating conditions of a wind
Turbine and send the measurement data to a certified monitoring center, e.g. as an eMail. The center monitors changes in the running and operating behaviour of the unit (TeleMonitoring, Level 1), identifies the causes of changes (TeleDiagnosis, Level 2), makes statements on the machine condition (Level 3), and looks for opportunities for improvement.