(1) Cut-in wind speed - this is the minimum wind speed at which the turbine blades overcome friction and begin to rotate.
(2) Cut-out speed - This is the speed at which the turbine blades are brought to rest to avoid damage from high winds. Not all turbines have a well-defined cut-out speed.
(3) Power curve - this is the steady power delivered by the turbine as a function of steady wind speed between the cut-in and cut-out speeds. For the WindPower program, these values are needed in wind speed steps of 1 metre/second.