ECN Forum Forums Technical Discussion Electrical Theory and Applications Sizing Power factor caps?

A few answers that I got so far from the utility company:

1. PF is 70.3
2. Billing demand is 255KW

Penalty is not so straight forward though, they factor in a couple formulas and then which ever is highest, that is the cost.

The POCO don't make understanding charges very easy, is that for a reason?

The guy was using words like "ratchet minumum", whatever that is...

Dnk..

[This message has been edited by Dnkldorf (edited 02-27-2006).]

Utility demand charges and power factor penalitites are not normally directly related.

A demand charge is a fee the utlity charges for having to provide equipment that will meet your peak KVA loading (even if they bill you per KW). A ratchet clause says they get to charge you at your highest demand rate for the next 12 months even if you never hit that level again. When calculating pay back remember it may take many months before your billed rate "ratchets down". I have at least 1 customer that will stop production in order to not exceed a specific demand level.

Power factor penalties are very utility dependent. Some will even have a larger penalty for exceeding "unity" then they do for being below it. I target my calculations at .95, this allows me to usually fall between .92 and .98 by the time I am done.

In my immediate area there is no major utility that imposes a PF penalty. They used to have incentives to correct PF but those ended almost 10yrs ago. now almost all PF is done to improve the customer's system performance only.

If the customer is being billed 255kw then there will be no reduction in the bill by improving the PF. The demand is probably not large enough to cause a PF penalty.

Dnk - I'm presuming you mean the numerical value for PF is 0.703?? Check out these numbers to see if I'm on tract here.

KW = 255
PF = .703, which means the phase angle is 45.33°.
KVA = 363
KVAR = 258 (which is more than the KW)
I tend to disagree. Although the utility may not charge for low PF, if they do, I'd say this one qualifies.

Radar

Radar
You make a good point. Most utilities that have a power factor penalty apply it at about 1000 kva. Loads smaller just do not cause a problem. There may be some utilities that may have a lower demand requirement.

Makes sense Bob. Even though the system Dnk is dealing with stinks (PF wise), it may be too small to incur a PF surcharge. But what if the customer is being billed for KVA demand instead? Seems like a good candidate for corrective measures in that case. Otherwise, not really worth fooling with?

Radar

Guys, I'm not quite sure how they bill yet, but, the guy at the POCO did a quick calculation. He stated if I corrected to .9, this would shave 35KW of the billing demand.

All charges, distribution, generation,transmission, and transition are based on billing demand...

This would appear to be a 13% reduction in costs..however small though..

This formula they use appears to be the most difficult part to understand so far..

This is a good beginner exercise for me..start small, and go bigger...

One other note, the past month has been slow here. They are in the midst of a product redesign again. I think I need a whole year of data to really be effective. So the PF could actually be lower, and the demand could actually be higher.

(anyone understand Exolon/Peco rate formulas?)

Dnk..

I gotta go catch a train, but I have time to throw a few numbers in here. at .9 PF:

PF = .9
Phase Angel = 25.84°
KW = 255 (as Dnk said)
KVA = 283
KVAR = 123

Some improvement indeed.

Radar

Quote:
"(anyone understand Exolon/Peco rate formulas?)"

No, but I work for a Utility and it gripes me to no end when one of our employees can't take the time to make an explanation understandable.

You have every right in the world to get a decent explanation of your billing. If you get a some nimrod who's only looking for quiting time, request to speak to someone else. Every Utility is just like any other company, you get good employees and bad ones. From reading these forums, I get the distinct impression that most customers get the bad ones.

DON'T TAKE IT! You are entitled to an adequate and CLEAR explanation.

(....deep breath....calm blue ocean..... ........ohmmmmmmmmmmmmmmmmmm...........)

OK. Rant over.

As for the remark that PF correction would lower your Kw demand, I think everyone here is in agreement that PF correction does not change your Kw. So I can only assume that;

1. You are billed on Kva rather than Kw, or

2. Your total bill incorporates a PF penalty that is addressed as a percentage of the Kw and added to it.

IN either case (warming up for another rant here), there is no excuse what-so-ever that the Utility cannot give you an adequate explanation of the way you are billed.

WFO, from what I got from him, it is #2...

The thing that erks me the most is how on their web site they publish their tariffs rates. They call one charge one thing, but call it something else on the bill. I guess they leave it up to you to figure out what is what..

And there is no mention of "ratcheting minumums" any where that I can find on the site under the HT tariff. Why can't they make it cut and dry?

Anyway back to the original topic..

I'll be down tommorrow, and take some quick measurements, let you know what I find..

Radar, you catch that train?

Dnk...