Generator noise / sound analysis

[sngpl]

We have two hydroelectric generators, 80 MW each. It has been noted that the generator noise changes when the generator feeds its own station service transformer. This could be due to harmonics. The only sources of harmonics I can think of are due to the bridges in the excitation system and the battery charger.

How can we analyze the effect of harmonics on the generator noise?
Any good links to Fourier Transforms?

 

[samuelliu]

See IEEE Std 85-1973.