I recently read about synchronous generator and some things really confuse me.. How does the excitation affect reactive power? I don't understand their relation.. For constant load and variable excitation, how does the power factor change? Icosø remains the same but both I and cosø change with excitation. I understood this behavior for synchronous motor but not for generator. Please connect the dots for me..Also, why is synchronous impedance obtained from OCC and SCC taken as constant for any pf at full load? Doesn't synchronous reactance vary with pf?