Evolution of Modern Wind Turbines Part A: 1940 to 1994 - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 159

drove directly a large-diameter 162-pole alternator at ground level, which was then connected
through an AC-DC-AC link to the Hydro-Quebec grid, to provide variable-speed constant-
frequency operation. The system was generally operated at reduced speed to ensure longevity,
and power was limited to 2.5 MW. Hydraulically-deployed aerobrakes at the rotor equator
were a back-up to the primary dual-disk mechanical brake above the generator.
(a)
(b)
Figure 3-36. The 4-MW Eolé VAWT. (a) General view of the turbine at Cap-Chat,
Quebec ( Courtesy of the Hydro-Quebec Company ) (b) Sketch of major components, inclu-
ding the direct-drive generator [Richards 1987]