As far as my genset it is not auto control it can be control manualy.Generators that produce AC at 60 Hz often have gasoline engines that run at 3600 rpm, but 50 Hz generators often run at 3000 rpm. (50 Hz = 50 cycles per second = 3000 cycles per minute, thus 1 engine rpm equals 1 cycle) However, alternators (genheads) can be designed to run at almost any speed desired. For example, many diesel engine powered generators run at 1800 rpm to produce 60 Hz power and 1500 rpm to produce 50 Hz power.
Some generators have a feature called "idle control," which slow the generator down to idle speed when no load is attached. Then, when there is a demand for electricity, the idle control circuitry detects the demand and increases the engine rpm back to standard speed. As someone else said, the answer to your question depends upon the exact design of your generator.
by Aaron Carman
by Jake Hertz