Sufficient Amperage

[adavey]

I'm installing new AC equipment and had to determine if the current service is of adequate amperage size for the new AC equipment.

MY QUESTION:
When I get the peak load from the utility company (given in KW)do I include power factor into my calculation to get amps ???????

 

[ron]

Re: Sufficient Amperage

KW/PF=kVA
You will use kVA to determine A.

 

[adavey]

Re: Sufficient Amperage

Thank You. I guess a PF of 0.9 is a good assumption????

 

[adavey]

Re: Sufficient Amperage

The utility company gave a spreadsheet for power consumption. However, they gave me power consumption in KW HOUR units for each month. How do I calculate peak demand (amps) from this info ????????????????????

 

[charlie b]

Re: Sufficient Amperage

Originally posted by adavey: How do I calculate peak demand (amps) from this info?

Regrettably, you don't. The best you can get is an average over the month. But that is not good enough to serve in a load calculation. They have to give you the peak value for each month, in terms of either amps or KW or KVA. That would be a set of 12 numbers, and you use the highest of the twelve. Are you certain that that information does not appear somewhere in their documents?

Often you can get the peak power number from the monthly bills. You might check with the owner/tenant, to see if they have the last year's worth of bills.

 

[charlie b]

Re: Sufficient Amperage

Originally posted by adavey: I guess a PF of 0.9 is a good assumption????

Depends on the type of facility. For an office building, I would probably use 0.9. For an industrial complex, I would probably use 0.85 or 0.80.

 

[adavey]

Re: Sufficient Amperage

The utility company gave me a spreadsheet (not a detailed bill)in microsoft excell format via e-mail . I will try to get the "peak demand" from the utility company. I appreciate the help.

 

[adavey]

The utility company is now telling me they don't have " peak demand " on record because it's a watt-hour meter (not digital). Are they telling me the truth ???????????? If so, how many different types of meters are there??????

 

[charlie b]

I can't comment on whether they are telling you the truth. But I can say that some utilities charge some customers (notably the large industrial types) not only for the energy consumed (kilo-watt-hours), but also for the peak power drawn (kilo-watts). If your customer is not being charged for their peak usage, then it would be reasonable for the utility not to have a meter that measures peak usage.

You have two alternatives that I can see. One is to count every single load in the facility, apply any demand factors that apply, and see how heavily loaded the facility is now. The other is to install your own meters at key locations, and measure the peak power draw over a 30 day period.

 

[steve66]

The utility company is now telling me they don't have " peak demand " on record because it's a watt-hour meter (not digital). Are they telling me the truth ???????????? If so, how many different types of meters are there??????

That is the case with a lot of meters out there. I would assume they are telling the truth since they don't have any reason to lie.

Steve

 

[adavey]

We have a measuring device called "dranet" (manufacturer name) that meaures current and voltage over period of time. However, its not very user friendly and I have yet to field test it. I guess nows a good time.

If that don't work I'lll go w/ Charlie B's Alt. 2. Thanks