Quote:
Originally Posted by chrismorse
Stepping back a bit, you might want to size the generator for the maximum probable intended usage.
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Another thing that should be reviewed is startup current vs. operating current. I chart all of the devices we plan to use, max current, operating current and expected minutes of use per hour. This way we can plan/design the system.
One thing, Generators generally do not have much for "surge". a 6KW unit can surge to 7.5KW for a few seconds. If you have an a 2 ton A/C (220V with LRA of 60 Amps), during startup you are drawing 13kW. You can reduce this with a start capacitor, by maybe 1/2.
The nice thing about using batteries and inverters, is that they generally can double the nameplate kW for about 2-3 seconds. If you have an 8kW inverter, it can supply 16 kW for a few seconds to help startup motors. It also allows us to operate with a smaller generator, run at full load (most efficient point) and let the batteries and inverter take the swing. If you buy an over sized generator for surge, you will be operating at a less efficient part load position.
Most of our designs use a 5kW generator (up to 2000 sq feet).