It has been a common experience that several phrases concerning the lifetime of wind turbines are used in the context of lifetime extension which can lead to diverse interpretations.
Consolidated definitions that clearly explain the terminologies concerning lifetime extension has been put forward by the consortium, as found here:
- Design lifetime: The time period used in the strength verification of the turbine during its design process as per IEC 61400-1.
- Lifetime extension: Additional period beyond the original design lifetime that the turbine is operational.
- Remaining Useful Life: Additional period from the present for which the turbine may be operated within an acceptable reliability.
- Operating life: Lifetime from commissioning to decommissioning of the wind turbine or wind farm.
- Safety: Prevention of failure which can result in risk of human injury or social or economic consequences or is in violation of local regulations.