Patent ID: 8154141

Claim:
Wind power installation comprising: a rotor comprising at least one rotor blade ( 12 ) connected to a hub ( 11 ); a generator ( 13 ), said generator being arranged to be driven by the rotor so as to produce electric power, said generator being connectable to a grid ( 4 ) for distributing electric power generated by the generator; a pitch control system for controlling the pitch of the rotor blades, said pitch control system comprising, for each rotor blade ( 12 ), a pitch drive (A, B, C) comprising at least one AC motor ( 100 ) arranged to interact with the corresponding rotor blade ( 12 ) for producing movement of said rotor blade around a longitudinal axis of said rotor blade; wherein each one of said at least one AC motor ( 100 ) is arranged to be fed by a converter ( 101 ) of the pitch control system; characterised in that the pitch control system further comprises means ( 102 ) for bypassing said converter ( 101 ) so as to connect the corresponding AC motor ( 100 ) to receive power from an emergency AC power supply source.