Performing Load Assessments

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primepower

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Hello everyone
I'm looking for all the information I can regarding performing proper load assessments to include what size generator would be needed to provide backup power say during a power outage. For example such things as lift stations that pump sewage and also small office buildings.
 
Some helpful resources:

1) As-Built Drawings.
2) Have an electrician hook a recorder up to the main gear to get a "real world" view of demand.
3) Nameplate ratings.
 
I use Peak Demand x 125% (consider starting current). Also, If you have large VFD(s) for your "sewage" equipment you may have a low PF for your pump, which brings further design issues.
 
adavey said:
I use Peak Demand x 125% (consider starting current). Also, If you have large VFD(s) for your "sewage" equipment you may have a low PF for your pump, which brings further design issues.
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That method might not work if you are using utility peak demand readings from the electric bill. In our area, that is a 30 minute average of demand. If you draw 200 kw for 15 minutes and 0 kw for the next 15 minutes, you could establish a 100 kw reading over that 30 minute period. Different utilities do it differently, but use their readings cautiously.

Jim T
 
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