What effect will high or low excitation have on the power factor in a generator assuming there is no automatic voltage regulator?
If the power factor is .9 and the excitation on the rotor increases or decreases what would the effect be to the power factor. a generalization of the effect is what im after or an idea of what calculations are needed to demonstrate the effect. Many thanks
It generally will have no effect, as the load determines phase relationship. Excitation on the generator affects your Eg.
if ur system is connected to an infinite bus then the effect is negligible. practically the change excitation leads to change in the generated terminal voltage.If the amount of excitation being applied is exactly equal to the amount required to make the generator terminal voltage exactly equal to the grid voltage (at the generator terminals), the power factor will be 1.0 (or, unity). If the excitation is less than required, the power factor will be less than 1.0, and usually is considered negative, and the power factor will be leading. If the excitation is more than required, the power factor will be less than 1.0, and usually considered positive, and the power factor will be lagging. PS: This is from a generator perspective.
what if your load is purely resistive, you will not have any phase shift, regardless of the excitation. If you have paralled alternators and one becomes excited so that it's Et is greater than the other, than the other will begin to motor, and lag the line current. It's not the higher Et alternator that causes the lead or lag, but the lesser Et alternator that becomes a load.