Generator Vibration

[eha]

I did a vibration measurement in a Generator. I fix the active power (60 MW) and change the reactive power, varying the excitation current(reactive power). The amplitude (in velocity) at 1x decrease when I decrease the reactive power.

There are a explanation for this?
There are a mathematical model for explain it?
what are the relationship in the reactive power and mechanical vibrations?

 

[zig]

In very simple terms, you have a mechanical unbalance vector and an electrical unbalance vector by varying the reactive power you are changing one of the vectors and phase relationships. When these vectors are in phase they are adding out of phase subtracting, hence lower vibration at one x.