generator load calculation

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dashco

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Hallandale Beach
I have had 4 generators installed for our customers that used a kilowatt averaging on the high and low month for sizing. NEC does not have an article to support this.
Is there a product (such as an undervoltage breaker) that would require a reset when the voltage is lost?
Is load shedding appropriate? What is the easiest way to reduce the
calculated load for emergency generator backup?
I purchased a Fluke 1735 Power Logger and am going to try and submit a
30 day reading under provision 220.87, Exception.
Any suggestions are welcome:confused:
 
dashco said:
I have had 4 generators installed for our customers that used a kilowatt averaging on the high and low month for sizing. NEC does not have an article to support this. ...
An article to support what? - sizing a generator by this method? I wouldn't think the NEC would. It's a design issue.

dashco said:
...Is there a product (such as an undervoltage breaker) that would require a reset when the voltage is lost?...
Yes, as you suggested, a UV relay on or in the CB

dashco said:
..Is load shedding appropriate? ...
Sure. These are design issues between you and the customer.

dashco said:
... What is the easiest way to reduce the
calculated load for emergency generator backup?...
A question:
When you say "emergency", do you mean:
1. Art 700 Emergency Systems?
2. Art 701 Legally Required Standby?
3. Art 702 Optional Standby System?

The answer to this really matters. There are different legal requirements.

dashco said:
...I purchased a Fluke 1735 Power Logger and am going to try and submit a 30 day reading under provision 220.87, Exception. ...
Okay, I'm lost. Submit this to who? 220.87 is generally used in lieu of doing a load calc to see if there is sufficient feeder/service capacity to install additional equipment.

Items 1 or 2 above have legal requirements to meet. Calculate them, meet them.

If you are installing under Art 702, you and the customer decide what to power up. Calculate it, meet it - don't forget to watch for:
1. leading pf on such things as VFD's, UPS's
2. Motor starting loads

If you are trying to power the whole plant, maybe the recording power meter data will help.

Perhaps a more detailed description of what you are trying to do will help.

carl
 
one additional thought:

You may have issues requiring a PE. Paraphrasing:

In some states, buildings for public occupancy, require a PE stamp on product of engineering (drawings, specs, installation details).

If not a public occupancy, the customer's engineer (customer's employee) can do the work, but not you. And the customer can just about call anyone they want an "engineer".

carl
 
I can only speak for Florida. The Generator and ATS must be sized to the connected load. Not a monthy reading from the power company. Yes you can install a Load shedding system. They work very well and solve the problem of having to buy a Large Generator.
 
But of course you can't shed Article 700 or 701 loads. What else is the generator feeding?

Steve
 
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