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#43094 - 10/05/04 05:53 AM Power Factor Monitoring by Utility
GamecockEE Offline
Member

Registered: 07/28/04
Posts: 49
Loc: Georgetown, SC 29440
Doing some research on energy saving for commercial and small industrial clients. Is power factor an issue for these size of power users? How do power companies monitor power factor for billing purposes for mid-size and large commercial users? Interested in how the information is collected and gathered. Or is this largely confined to big industrial users where the cost of a SCADA link is justified. Thanks

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#43095 - 10/05/04 09:26 AM Re: Power Factor Monitoring by Utility
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
There are thousands of electric utilities in North America, so there will never be a pat answer. Get a copy of the subject utility’s rate or tariff and study that. Many are available at their sites.

Often they are based on monthly kWh and kVARh consumption, but some use coincident kW and kVAR demands read from meter registers. There are surely other methods.

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#43096 - 10/05/04 12:50 PM Re: Power Factor Monitoring by Utility
GamecockEE Offline
Member

Registered: 07/28/04
Posts: 49
Loc: Georgetown, SC 29440
Bjarney, do the power companies typically monitor commercial facilities for KvarH and demand Kw and Kvar? I was hoping that some of our utility forum participants could shed some light on what would trigger the need for that level of metering from a utility point of view.

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#43097 - 10/05/04 04:30 PM Re: Power Factor Monitoring by Utility
CharlieE Offline
Member

Registered: 04/23/04
Posts: 204
Loc: Indianapolis
You have already gotten the correct answer.

We have two commercial general rates that we use most of the time (SS & SL or secondary small and secondary large). The cutoff is a 50 kW of demand to get the demand rate. If you are on the demand rate, you will be charged for the energy used, the maximum or peak demand in the last year, and for your worst power factor during the billing cycle. Under 50 kW of demand and you are charged for energy usage only, the demand and power factor is not measured.

Other electric utilities do it differently.

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Charlie Eldridge, Indianapolis, Utility Power Guy
_________________________
Charlie Eldridge, Indianapolis Utility Power Guy

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#43098 - 10/05/04 05:47 PM Re: Power Factor Monitoring by Utility
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
 
It is probably a mistake to base the feasibility or payback interval by assumption of a utility’s tarriffs, or that they are the same as a neighboring utility. Power-factor clauses in tarriffs can be complicated.

¬†¬†¬†[An example] ‚ÄúFor calculating the power factor, the District will determine the ratio between kilowatt and reactive kilovolt-ampere (kVAr) by means of installed instruments. In any billing period when a customer‚Äôs maximum 15-minute reactive kVAr demand is in excess of 62% of maximum kilowatt demand in the current or previous 11 months, an additional charge for each reactive kVAr of such excess will be made. At the District‚Äôs option, the power factor may be determined by means of periodic tests. If determined by tests, the resulting power factor will remain in effect until a new determination is made.‚ÄĚ

Sixty-two percent in the example equates to a PF of 0.85, which is a fairly ‚Äėgenerous‚Äô condition. Others have penalties outside of 0.97 lagging to 0.97 leading PF‚ÄĒNow that‚Äôs stiff ‚Äúretribution.‚ÄĚ




[This message has been edited by Bjarney (edited 10-05-2004).]

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#43099 - 10/05/04 07:14 PM Re: Power Factor Monitoring by Utility
CharlieE Offline
Member

Registered: 04/23/04
Posts: 204
Loc: Indianapolis
 Quote:
Sixty-two percent in the example equates to a PF of 0.85, which is a fairly ‚Äėgenerous‚Äô condition. Others have penalties outside of 0.97 lagging to 0.97 leading PF - Now that‚Äôs stiff ‚Äúretribution.‚ÄĚ
Actually, most electric utilities end up doing the same thing but it looks differently. We have a line at 85% power factor. In other words we bill for a power factor that is worse than 85%. However, we will give a credit for power factor that is better than 85%. The bottom line is the same as your example but it sounds better. I have seen another electric utility that sets up the billing to charge for the kVA instead of %PF. Of course you can cut the kVA by correcting the PF.

(edited to add the signature line)
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Charlie Eldridge, Indianapolis, Utility Power Guy

[This message has been edited by CharlieE (edited 10-05-2004).]
_________________________
Charlie Eldridge, Indianapolis Utility Power Guy

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#43100 - 10/06/04 05:25 AM Re: Power Factor Monitoring by Utility
GamecockEE Offline
Member

Registered: 07/28/04
Posts: 49
Loc: Georgetown, SC 29440
Thanks for the info. you helped clear up some of the questions that I had. I knew that the utilities varied in their charges. In your opinions, are the customers out there aware of the penalties that they may be paying for being out of the power factor window, or is power factor a non-issue due to better technology ( such as HPF ballasts in lighting)?

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#43101 - 10/06/04 02:39 PM Re: Power Factor Monitoring by Utility
CharlieE Offline
Member

Registered: 04/23/04
Posts: 204
Loc: Indianapolis
"I believe" our customers know they are being billed for the poor power factor because it is only the larger customers that are put on the better rate. These customers have "generally" had contact with one of our marketing types and had the billing explained to them (doesn't mean that they listened).

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Charlie Eldridge, Indianapolis, Utility Power Guy
_________________________
Charlie Eldridge, Indianapolis Utility Power Guy

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