Colleen, I wanted to answer you question a little further:
Lets say you have a 3 phase generator{120-208volt} For this example we will use LitePower's configuration with a Basler or Marathon voltage regulator.
As the engine spins the generator around, it passes each "leg" The leg's are spaced equally in a circle, as it passes the leg that is loaded heavy, the engine has to work hard to produce enough power to satisfy the demand{engine slows down a little}, then it passes a leg that is loaded light it doesn't have to work as much so it passes quickly. This will cause engine speed to vary wildly{Hz or Frequency}. Also , most of our 60,120,and 140kw generators use 2 legs to control voltage. The voltage regulators function is to maintain a constant voltage between phase 1 and phase 2 to our pre-set point of 208 volts. As the leg loaded heavy goes by, the regulator looks at it and says"increase" but when it see's the leg loaded light it say's "decrease". Phase 1 could be as much as 20 volts too high, and phase 2 could be 20 volts low, however measured between them you still get 208 volts, measure line to neutral and it wont be 120 volts. This is a bad thing,however some generators use a three phase voltage regulator{this is the case with our 220KW Generators} with a PMG generator{Perm. magnet generator}. This type of generator is much more forgiving in regard to balancing as each leg is adjusted separately.
Also, use the ballast, not the generator's circuit breaker, and ground properly, especially when using dimmer racks.