the reactive power this information is also time averaged over a period of time which corresponds or substantially corresponds to the preselected time period over which the mechanical data are averaged or have been averaged the power estimator 26 uses both the estimated value t e for the mechanical rotor power and the desired value p s for the electrical power in order to calculate the estimated value p e for the electrical power according to a configuration the power estimator 26 uses a table 53 power table or an equivalent functional tool to produce relationships in order to store estimated values for the electrical power when the wind turbine 1 is operated under different conditions for simplification the stored relations are each established during operation of the wind turbine 1 in the stationary state however the stored relations or some of the stored relations may also be established during operation of the wind turbine 1 in the acceleration state and or in the deceleration state if the additional costs thereby caused are acceptable the estimated values stored in the table 53 for the electrical power that is to say the expected values for the electrical power are functionally dependent on the stationary mechanical rotor power the rotor speed the ambient temperature preferably air temperature and the adjustments preferably desired values for the effective power and reactive power according to another configuration the table 53 is functionally dependent on the following variables the stationary mechanical rotor power the rotor speed the ambient temperature the adjustments for the effective power and reactive power and the rate of change of the variables mentioned according to another configuration the power estimator 26 uses a.