Estimating KWh electicity billing using clamp-on amp meter

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On 5/30/2011 6:58 PM, dpb wrote:

As a ghost of 101 - I think you want Blondel's theorem. Probably the only time it will appear in this newsgroup.
--
bud--



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..

Thoroughout this discussion it's been clear that Homeguy has been talking about KWh from his bills. I don't know what kind of bills you get, but every bill I've seen shows the METER readings and then seperates out any rate issues. In other words, they send you a bill for 1000Kwh at rate 15c and 300 at rate 20c. I haven't seen one adjusted for peak usage, but it sure would seem that would be handled on the bill by some obvious multiplier, like 1.3X, etc.
For what you are suggesting to be behind what Homeguy is seeing, the meter would have to be taking all that in to account, instead of giving true Kwh usage, peak demand, time of use, etc and then having the billing folks calculate what to do with it and show it on the bill. And then you would never see the true Kwh used, which has been on every electric bill I've ever seen.
Don;t you think Homeguy can read a bill?

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The accuracy is the same range as any other meter.

There is some confusion here. Power factor then is the ratio of active power to total power. Power factor comes into play, mostly when you have a lot of large motors. Yes, you set the reading during startup with the inefficient motors. You can correct this by using a bank of capacitors properly sized. Or with a capacitor at each of the large users, such as a 150 HP air compressor.
I don't claim to understand it all, but I do know it exists. http://en.wikipedia.org/wiki/Power_factor http://www.myronzucker.com/calmanualpg1.html

Questionable, but done all the time.
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On 5/29/2011 9:23 AM, Ed Pawlowski wrote: ...

What's there to question about it?
As noted, the utility must supply the facilities and generation capacity to satisfy peak demand, not average. That costs and the use of demand-based tariffs provides a strong incentive to the end user to be aggressive in implementing load-leveling techniques to the end benefit of both utility and themselves.
--
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Specifically the ratio of real power to real+imaginary power. ;-)

If the motors are fully loaded the PF will be close to one. A lot of unloaded motors will have a low PF, as will a pile of electronics (specifically ones with switching regulators), but for different reasons. Capacitors will correct the former but will do nothing for the latter.

No, that's real power being used.

Capacitors do nothing for start-up currents.

Not questionable at all. It makes perfect sense for large customers, as does charging for power factor. None of this has anything to do with the OP's problem, if he really has one, though.
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" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote:

In actuality, the larger the motor, the greater will be it's power factor.
Fractional HP motors (1/8, 1/4, 1/3, 1/2, etc) have low power factors (37% to 66%).
Motors above a dozen hp have power factors of 85% or better.
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Those motors are only better because they are usually sized properly and are running near their rating. If you lightly load such a motor, it still can draw a lot of current, but out of phase with the voltage. Little real power is being used, but lots of VAs. Another way of looking at it is a lightly loaded motor is acting like an inductor. The more real mechanical load applied to the motor, the more real electrical power is required. The motor looks more and more like a resistor as the power reaches the design limits of the motor.
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No. As others have said, the peak determines the rate used. For example, if your peak is below 5 KW, then you might be billed at 12 cents per KWH. If your peak goes above 5 KW, you might be billed at 15 cents per KWH. Those are just made up numbers. Your rates at various peaks will be different. In summary, your peak is based on just a few seconds, but you bill is still based on actual usage.
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wrote:

** The point being, if you are totally ignorant as to how the dollar amount on the electric bill is determined, the first place to ask questions is the company supplying the electricity and providing the bill. Once you get all those nasty details figured out, you'll have a better idea of how to go about verifying the numbers
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Home Guy wrote:

Because the cost to generate the electricity is small compared to the cost to deliver the energy. The cost to deliver the energy, in turn, is determined by the infrastructure needed (poles, transformers, generation capability, etc.). A commercial customer with even a short peak demand may require more infrastructure to support that demand than dozens of residential customers.
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HeyBub wrote:

So what would you consider or where would you place the threshold for which demand metering should be used by a customer?
What monthly kwh usage would you consider "worthy" or significant enough for an electricity supplier to use a demand meter to cover this so-called significant cost of delivering this huge amount of brief peak energy?
Would you consider, say, 2000 kwh? Would a single month's total usage of 2000 kwh qualify a customer for a demand meter? Would 4 consecutive months of 2000 kwh be the line-in-the-sand for putting a customer on a demand meter?
http://www.nationalgridus.com/niagaramohawk/non_html/eff_elec-demand.pdf
Demand meters for such small users are total bullshit.
Anyone with a 100 amp, single-phase service that is using their service at 50% for an entire month would tip the scale at a 4300 kwh bill. Hardly what I'd call justified for utilizing 50% of the smallest installable utility service.
How would you justify the infrastructure costs needed to supply such a paltry service such that demand metering is needed?
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On 5/29/2011 8:04 PM, Home Guy wrote: ...

On the basis that it the assertion that it's not generation but transmission only that matters--it's both.
Given the restrictions on new generation facilities and tightening regulation on existing, if there's any growth in demand there's getting to be nowhere from which to get it.
Applying demand metering shifts (or at least increases) the interest of the user that previously hasn't ever cared by the only really effective behavior-changing device--the pocketbook.
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It's not the monthly kWh usage that determines whether demand metering is used or useful. It's the *peak* usage and when that peak occurs. The infrastructure has to be built for the largest demand, not average. Where the threshold is placed is a different matter for each power company.

I don't believe any residential customers have demand metering, but I could be wrong.

Define "such small".

You wouldn't have demand metering with a 100A service. ...at least not a residential service.

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On May 29, 10:11pm, " snipped-for-privacy@att.bizzzzzzzzzzzz"

yes you might. APS in Arizona offers demand metering to residential customers, (at least they did when I lived there)
The so called PEAK demand was based on the highest power used during any 60 minute period over the billing period. With demand metering, they lower the kWh rate but they charge you also for the peak. For example, with standard billing you might pay $0.12 per kWh. With demand billing you would pay $0.06 per kHW plus $5.00 per peak kWh. So for example if I used 100kWh during and a peak of 5 kWh during the month the charge would be $60 plus $25. If you are just a little careful you can save a lot of money. If you are just a little careless it can cost you a lot of money.
Also following this thread some of you seem to be mixing up power factor and demand billing, they are two different things. Some industrial billing plans bill by kWh, peak kWh AND power factor.
Mark
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Isn't it a TIME metering (usage in peak times is metered differently than off-peak times)? Peak metering on such small loads would be dumb.

Yes, we've already discussed all that. Ad-nauseam.

You're not following this thread, then. People are trying to figure out what is causing the moron OP to run around with his hair on fire.
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" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote:

http://www.nationalgridus.com/niagaramohawk/non_html/eff_elec-demand.pdf

2000 kwh per month is "such small".

And 4300 is more than 2 x 2000.

Did you read the link?
A 100 amp service is 4 times what you need to draw 2000 kwh in a month.
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OK.
Say it ain't so! That would be *highly* unusual and would not be an issue with demand metering, now would it? <shakes head>

Yes, did you? It talks about residential customers not having demand metering.

Good grief, you're stupid!
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" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote:

So you agree that 2000 kwh is a pittance.

So what?
Why should any utility put a demand meter on anyone pulling only 2000 kwh per month?

If that statement is incorrect, then you tell us how many kwh a 100 amp single phase service can provide in a month (730 hours in a month, btw).
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I agree that you're a moron, but I'm certainly not alone here.

They certainly didn't. Why do you insist they did?

It's not, but that doesn't change the fact that you're stupid as a stump.

It might be correct, but completely irrelevant. Unless your power company (or PUC) is totally whacked, you wouldn't have demand metering with such a puny service.
Now, why don't you listen to the people you're asking question of? Or put another way, why did you ask if you don't want the answer?
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" snipped-for-privacy@att.bizzzzzzzzzzzz" wrote:

This electricity provider (National Grid) serves close to 4 million customers across 29,000 square miles of Massachesetts, New Hampshire, New York and Rhode Island.
This is the link:
http://www.nationalgridus.com/niagaramohawk/non_html/eff_elec-demand.pdf
And this is what it says:
==========National Grid installs a demand meter whenever a customer's energy consumption has exceeded 2000 kilo-watt hours (kWh) per month for four consecutive months. Once demand billing begins, it does not end until after the monthly energy consumption has been less than 2,000 kwh for 12 consecutive months. This requirement may not be avoided by temporarily terminating service. New or existing customers whose connected load indicates that the energy consumption will exceed 2,000 kwh per month will have a demand meter installed. The demand charge will be the hightest average kW measured in a 15 minute interval during the billing period, but not less than one kw and not less than the demand contracted for. ============ Now take your foot out of your mouth and explain why such an agressive policy is needed for a demand meter for such a paltry energy usage.
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