I was recently asked by a client to quote on installing services for a new process. The service capacity needed to be reviewed as the load was substantial. Our code allows us to use peak demand over the previous 12 month period, as a demand loading for the installation. On request, the utility provided me with an hour by hour reading of the plants draw. Because the exsisting plant has several sections that can be run at different times, I requested representative production records for the same period, to compare draws with activities. Based on the current demand, anticipated additional demand, and production activities, I was able to recommend to the client several options for thier consideration.

During this process, at no time did I think, uhm, I wonder if the utility is ripping off this company. Nor did I consider balancing, as it was irrelevant at this point.

I'm going to say that this thread is going nowhere. The accusers are as vague as the accused. Either put on the beef, or close the BBQ.

 

I'm going to say that this thread is going nowhere. The accusers are as vague as the accused. Either put on the beef, or close the BBQ.

Sorry, but I disagree. Some useful and informative information was posted, especially by PB.

Chris

 

maybe the question eluded me then.

The traditional mechanical meters measured the billed component. Reactive draws incurred aren't measured. This traditionally wasn't a problem for the utility. They did measure VA at distribution nodes, and if something was amiss, they'd have to 'walk the block' to track down the source. These days, 'residential' has a broader usage, and it's to the utility's advantage to better resolve who's using what. Add to that the expense of data collection. If, within the 'residential' usage, I add a reactive component above the reasonable design, it would fit logic that I may be billed for that. The digital meters do measure this, but most utilities don't bill for it. They will however drop by if your 'out of bounds' on the draw.

The first thing these guys need to be asked, is does the utility bill on VA or Watts. The second question is there a penalty for exceeding some VA.

Then comes the accusation that the meter fails to measure accurate Kw with a high reactive current. Due to it's construction, the meter only produces mechanical torque when the voltage is in phase with the current. It does not turn (accumulate) with out of phase current.

So again, maybe I've missed the question. Is it that the meter fails or that the utility is ripping them off. One is conspiritorial, the other mechanics. At this point, I don't know which route your walking.

 

This link was also present in the KVAR Power factor correction link that I found recently.

http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903669

 

This pdf has a lot of info about kwh meters.

http://www.usbr.gov/power/data/fist/fist3_10/vol3-10.pdf

The typical accuracy is better than 1%.

The meters shouldn't have errors greater than that regardless of the mode--120V or 240V.

 

This link was also present in the KVAR Power factor correction link that I found recently.

http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903669

Ha! When I opened it and read "Carbon Footprint" I damn near clicked the close button do to knee jerk reaction! Glad I didn't though. It was an enjoyable read.

Thank you!!

Chris

 

This pdf has a lot of info about kwh meters.

http://www.usbr.gov/power/data/fist/fist3_10/vol3-10.pdf

The typical accuracy is better than 1%.

The meters shouldn't have errors greater than that regardless of the mode--120V or 240V.

This is an outstanding contribution to this thread. There's quite a bit of data to read through but the initial scan of the material appears to be exceptionally informative.

Thank you,
Chris

 

maybe the question eluded me then.

<snip>
The first thing these guys need to be asked, is does the utility bill on VA or Watts. The second question is there a penalty for exceeding some VA.

Then comes the accusation that the meter fails to measure accurate Kw with a high reactive current. Due to it's construction, the meter only produces mechanical torque when the voltage is in phase with the current. It does not turn (accumulate) with out of phase current.

So again, maybe I've missed the question. Is it that the meter fails or that the utility is ripping them off. One is conspiritorial, the other mechanics. At this point, I don't know which route your walking.

GDI, thanks for the input. The primary goal of this thread is not related to reactive (VA) power or whether or not the KWHM reads it accurately, inaccurately, or at all. I never thought it did. My belief has always been that it's a 'true' wattmeter that will factor in reactive loads correctly.

The purpose of this thread is to disprove or prove that KWH meters are less accurate when measuring a 120V load (single leg measurement) vs a 240V (balanced measurement) load. I do believe it's been satisfactorily answered and the verdict is a resounding no.

I think the reason that this myth was born in the first place may be related to the known benefits of 240V loads. I have only two 240V machines in my shop but I would be happy if they were all 240V. Any power that's not being burned up as heat in the conductors will translate into KWH savings on my monthly bill, even if it's small.

Thanks for the input,
Chris

 

Gentlemen, some have asked what specifically have the claims been, so I thought I'd include a few here.

I was replacing a 120V 1/2Hp motor on my stationary belt sander. When I mentioned (to my group) that I was going to replace it with a 240V model. These are some of the replies that I received. I removed my members names to protect the Innocent. ... Except for me.

If commenting please be kind because they will be reading this thread.

Running the 240v, the meter does not run as fast. Less KW usage.

Who told you that myth? 240V service is preferred to reduce voltage drop on the conductors. A dual voltage motor (120V/240V) will draw 1/2 the current when configured for 240V. The wattage remains the same.

Chris

This is true...... And will be getting much worse in the near future as the power companies now have thee ability to measure power factor on residential meters. The loss in efficiency really does not matter to the power company as they are only feeding your home from a single phase of high voltage, but the meter will read the imbalance and spin faster on a heavenly loaded phase.

BTW, I attached a spice image, primarily for my members, that might explain how the myth got started. There isn't any revelations in there for you guys though.

 

A few months ago they replaced my old meter (had it 36 years) with the new digital/microwave link model. I don't have any complaints except for the third eye I'm growing.

My take is that anytime an electromechanical or mechanical part can be eliminated and or replaced by a solid state device it's generally a good thing. The big question is how it will stand up to the daily light shows that we have here during the summer months?

Can you tell me who made your new meter? I have some friends over at Sensus, Itron, and Elster and might be able to squeeze some info out of them.

 

Can you tell me who made your new meter? I have some friends over at Sensus, Itron, and Elster and might be able to squeeze some info out of them.

It's made by GE.... 'Government Electric'.

Chris

 

This is an old thread I know, but I found a relevant article which I found interesting. But I guess it applies more to company bills.

http://downloads.eatoncanada.ca/dow...trical Bill Without Reducing Energy Usage.pdf