Engine rotating a generator at its rated speed, but engine power exceeds power required? What would occur if a gasoline engine would be driving a generator (specifically, a permanent-magnet synchronous AC 3-phase sinusoidal generator) as its only load at the output shaft and if that engine is rated at i.e. 35kW @ 8000 RPM but at the same speed the generator is rated to produce 30 kW of electricity, at 120V / 250A?
Is a “rated power” of an internal gasoline engine a rating for its maximum possible power output at a certain RPM? Meaning that if a load (in this case, the generator) requires less power input from the engine then the engine throttle would be positioned as such to allow the required fuel amount to be consumed, but not the maximum safe possible (because it is unnecessary)?
If the load at that speed would be larger (i.e. 35kW, and not 30) then the throttle would need to be opened more to increase the fuel flow to produce the required power?
Or does the engine produce 35kW at 8000 RPM regardless of generator load and the 5kW is unused i.e. dissipated through heat?
Excuse me if this is too simple but I would like to find clarification regarding this.
Thanks
 A: For a real application, the engine would have some type of feedback control that attempted to hold the engine at a constant rpm.  If the load increased, the rpm would decrease, and more fuel would be sent to the engine to get back to the rpm setpoint.  The opposite would happen if the load decreased.  For the "extreme" case where the load exceeded the engine's capability, the engine would go to full throttle, but it wouldn't be able to meet the rpm setpoint, and it wouldn't be able to produce the required electrical power output.
A: Most gasoline engine powered small AC electric generators have a governor on the throttle to keep them running at a fairly consistant rate of revolutions per minute. This keeps the AC phase steady. When the generator has a load increase or decrease the governor will open or close the engine throttle accordingly to keep the revolutions per minute constant under different loads. When there is a heavy load the throttle will be open more, burning more fuel than when there is less load on the generator.
