Generator sizing

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Is there an industry standard when it comes to sizing a generator for an application be it rsidential or commercial? I have spoken to several distributors and they suggested 805. I have seen several installation where the generator output breaker does not fall into this percentage.


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Re: Generator sizing

There is no industry standard. There is practical electrical engineering fundamentals for sizing the generator for the load.

What is 805?

[ May 06, 2003, 07:42 PM: Message edited by: bennie ]


Re: Generator sizing

A generator is sized based on the load it has to support. NEC lists the mandatory emergency load,
that must be supported by the generator. Beyond that - it is the facility owner's preference and design/operations engineers' opinion on what has to have the back up power. Once you know the load
it depends on the type of load: for a non-motor load the safe way is to have generator's KW equal to the total load KVA - because you would not be able to calculate the load's power factor exactly. If you have motor load, than you have to use one of the available software
(and there are plenty of them) to account for the voltage drop due to in-rush current. Some generator manufacturers have a program on they internet site (Genarac for example) where you can do it for free right off Internet.
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