The electricity is generated at voltages around 400 V and up to 2,300 As and at variable frequency proportional to the variable speed of the rotor. All produced energy is converted into direct current DC by a rectifier inside the nacelle and conducted to the inverters located in the bottom of the turbine tower. The inverters modulate the DC into alternating current (AC) with 50 Hz grid compliant frequency. Each turbine has a transformer inside the tower which transforms the voltage to the 20 kV internal grid voltage of the wind farm. At the tail station a wind farm transformer is increasing the voltage to 110,000 V and fed into the ESB network through 21 km underground cables.