The increasingly onerous demands on drivetrain reliability are spearheading rapid advances in wind turbine transmission technology, with permanent-magnet generators (PMGs) coming of age in the next generation of machines, promising higher output and efficiency, and lower maintenance costs. PMGs' offer of high performance is brought into sharp relief under "partial load" - the most common operational state, due to the inconsistent nature of the wind - where they have demonstrated efficiencies of up to 98% in blustery conditions, and energy production yields as much as 8.5%