Generator Sized for Connected or Demand load?

[Gshell82]

That's basically my question, is an E/G sized for the connected or for the demand load?

Thanks

 

[electrofelon]

That's basically my question, is an E/G sized for the connected or for the demand load?

Thanks

It is sized for the NEC calculated load.

 

[kingpb]

It is sized for the loads that it will serve; also accounting for the ability to handle the initial start-up inrush of those loads.

 

[drktmplr12]

That's basically my question, is an E/G sized for the connected or for the demand load?

Thanks

Cummins, probably others, has software that you can enter the loads, in terms of kW and the order in which they turn on, if any. The program spits out the size gen they recommend. Generally, you need the E/G to be able to momentarily supply starting kVA to the largest motor while all conceivable loads are running. If the engine can't provide the energy needed to start the electric motor, the generator field will break down and both the electric motor and engine will stall.

There's more to it than that including (not limited to) considerations for harmonics, load diversity, and what type of mechanical load is being driven by a given electric motor.

Additional reading
ECM Article
Kohler white paper

 

[kwired]

with manual transfer equipment kind of doesn't matter, user is able to select what loads are used.

With automatic transfer equipment - NEC doesn't want an unsupervised system to transfer automatically to an overload condition, but does allow for automatic means to control what loads can run when the generator is in use - commonly called "load shedding".