Some quick research on generator excitation: * Each of Hoover Dam's generators appear to me, based on this photo [1], to have three stages of excitation, verti

Some quick research on generator excitation: * Each of Hoover Dam's generators appear to me, based on this photo [1], to have three stages of excitation, vertically stacked on the rotor shaft. * A year 2010 upgrade to digital controls at Hoover Dam [2] shows: ___ o A total plant capacity of 2.074 GW from the 17 generators ___ o 20 seconds to go from reactive power control ("condense mode") to generator mode. ___ o Pictures of the original and replacement governor equipment; the red cabinetry shows a beautiful 1930s design style * In "condense mode" [3], the turbine's penstock valve ("wicket gate") is closed off, the turbine volume filled with compressed air to displace the remaining water, then the generator operated as a massive synchronous motor. In this mode, the excitation controls can provide marketable power factor correction, aka "reactive power" for the grid. ------ [1] http://bayimages.net/view-photos/electric-power-generators-hoover-dam-13772.html http://bayimages.net/view-photos/electric-power-generators-h... [2] http://www.hydroworld.com/articles/hr/print/volume-29/issue-2/cover-story/rehabilitation--hoover.html http://www.hydroworld.com/articles/hr/print/volume-29/issue-... [3] http://www.bpa.gov/Finance/RateCases/BP-14RateAdjustmentProceeding/Documents/BP-14-E-BPA-26.pdf http://www.bpa.gov/Finance/RateCases/BP-14RateAdjustmentProc...