Introduction to Wind Turbine Technology - Small Wind Turbines: Analysis, Design, and Application - page 28

24. As noted in the text, the Skystream 2.4 kW turbine has all its electronics in the
nacelle, rather than mounted in the tower at its base or a nearby special
container. What are the advantages and disadvantages of these possible
locations for the electronics?
25. Starting with the web sites listed in Table 1.9 , find the typical efficiencies of
PMG in the range up to 10 kW to see whether they are more efficient than the
IGs in Table 1.4 .
26. The ''theoretical'' n for the R n -dependence of blade mass is 3, which is greater
than the actual value seen in Fig. 1.13 . Why would you expect this behaviour,
rather than the actual value being greater than 3?
27. The blades on the V80 turbine weigh 6,500 kg each. Compare this to the data
correlation of blade mass in Fig. 1.13 .
28. If the blade mass scaled as the cube of the radius, what would be the mass of a
2.5 m blade given that the 40 m blade weighs 6,500 kg. Answer: 1.59 kg
29. A standard induction motor has a synchronous speed given by n s = 120f/N P
where f is the frequency (in Hz) and N P is the number of poles. If the max-
imum f is limited to 50 Hz, and ignoring generator slip, determine whether it
is possible to design a small wind turbine for each of the generators listed in
Table 1.5 without the use of a gearbox.
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