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Verifying POCO meter

Posted by bus_driver (My Page) on
Fri, Jan 11, 13 at 16:49

I have one premises where the meter readings for power usage are much higher than similar properties. No electrical problems on the premises that I can find and I know that no unusual usage patterns exist at that premises. No way for outsiders to tap into the power supply. Searched in vain for metering that I can buy that will read watt-hours from the interior panel without having to disturb the service conductors? Is there watt-hour metering equipment that uses clamp-around current transformers similar to the popular amperage testers?
The power company will not cooperate with me on this situation.


Follow-Up Postings:

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RE: Verifying POCO meter

TED (The Energy Detective) just puts a pair of current probes around your main service conductors (you need a special set if you have 400A service). The box is the nicest of the power monitors I've seen and has a great API if you want to write computer software to make use of the data.


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RE: Verifying POCO meter

I have a TED and its pretty useful in more than one area. Feel free to contact me if you need.


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RE: Verifying POCO meter

I appreciate this information. While searching for a supplier of this unit, the user reviews posted on Amazon popped up. The fact that positive and negative reviews are about even has given me pause. Additional suggestions welcome.
I prefer to not have a computer involved. I just want to verify the POCO meter readings over a few days. I do not live at this premises and want the meter to retain it's cumulative readings until it is reset.

This post was edited by bus_driver on Sun, Jan 13, 13 at 8:04


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RE: Verifying POCO meter

Try emon demon meters.


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RE: Verifying POCO meter

You don't need a computer to run TED. It has a pretty nice display of it's own.


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RE: Verifying POCO meter

I suggest a measure of caution with use of energy meters that only measure current. To accurately measure energy use/power, it is necessary to measure current, line voltage and the phase angle between them (power factor).
A meter such as this TED device appears to only measure current. If you put it on the same circuit as a load that has a PF of less then 1 (well pump, air conditioner, refrigerator), you will notice that it never gives the same reading as the POCO meter, it will nearly always read higher.


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RE: Verifying POCO meter

paulusgnome61 makes a good point. I do not know what system is in New Zealand, but if the 120 power supply to the unit is monitored, that could take care of the voltage reading for the KWH reading. Disconnecting the panel supply conductors is not practical for my application. One of the loads is a heat pump, which would have a PF of less than unity.


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RE: Verifying POCO meter

"One of the loads is a heat pump, which would have a PF of less than unity."

Anything but a straight resistive load has a power factor less than one, and the factor varies with the load placed on the motor.

Current is NOT power.

Power is Voltage * Current * Power Factor, all measured at the same instant.


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RE: Verifying POCO meter

The TED I have measures voltage of both 'phases' and current. The module that installs in the main panel has both two current sensors and a connection for each phase. This module communicates wirelessly to another module located elsewhere in the home that stores all the sample readings. This second module can communicate via ethernet to a PC or wirelessly to their display.

There are some units out there that attach to the meter and record the revolutions.

The Aztech meter, available from some west coast power companies, listens to the wireless 'chirp' the meter makes when sending out data to the power company network (not necessarily smart meters). It sees what the meter is sending. www.aztechmeters.com

Another meter reader is from www.bluelineinnovations.com

I know there are others out there that measure power in the panel, but I'm too lazy to search any farther.


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RE: Verifying POCO meter

"The TED I have measures voltage of both 'phases' and current. "

The problem remains how fast they measure and how the measurements are synchronized to each other.

you need at least around 600 measurements per second, with an accuracy between them of 1/6000 of a second to get much of anywhere.

While not very fast in the electronics world, the synchronization of separate sensor samples remains a PITA for practical systems that are distributed.

If you bring the sensor readings into a single unit the timing gets far easier.


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RE: Verifying POCO meter

The POCO meter in this instance is an electronic meter, installed about 6 months ago. Since many meters in the same area are still the ones with the horizontal rotating disc and dials, I assume that smart metering capabilities are not yet fully in place. But even the older meters were retrofitted some years ago to permit short range remote reading-- like from a passing vehicle.


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RE: Verifying POCO meter

I have a 'smart meter' but it doesn't have all capabilities active according to my POCO. I know that my TED is really accurate to my meter at the end of the month. I can adjust how quick and how sensitive the readings are updated on the TED.


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RE: Verifying POCO meter

Here's another one.

BTW: you DO know what unexplained high energy usage can point to, don't you? ;-)

Here is a link that might be useful: panel power meter


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RE: Verifying POCO meter

Here's another one.

BTW: you DO know what unexplained high energy usage can point to, don't you? ;-)

Here is a link that might be useful: panel power meter


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RE: Verifying POCO meter

I don't know why I did not think of this last week. Why inject power factor into this discussion? My understanding is that for residential properties, the POCO does not measure the power factor of a residential customer.


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RE: Verifying POCO meter

I don't know why I did not think of this last week. Why inject power factor into this discussion? My understanding is that for residential properties, the POCO does not measure the power factor of a residential customer.


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RE: Verifying POCO meter

" My understanding is that for residential properties, the POCO does not measure the power factor of a residential customer."

The meter only measure dissipated power.

It takes the power factor into account when measuring the power used.

That is why measuring just the current and assuming a constant voltage does NOT tell you what the dissipated power is.

Residential is not billed by power factor (usually large users pay MORE per kW-hr dissipated if they have a bad power factor).

The meter on your house is a kW-hr meter, not a VAR meter.
They are purposely designed to be insensitive to reactive power.

Only the in phase voltage and current (the power factor) cause dissipated power.

This post was edited by brickeyee on Fri, Jan 25, 13 at 9:56


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RE: Verifying POCO meter

"Only the in phase voltage and current (the power factor) cause dissipated power. "

In a purely resistive circuit, there is no power factor because the voltage and current are in phase (unity).

True power(watts)= Applied voltage X resistive current

VAR= Applied voltage X reactive current

VA= Applied voltage X the vector sum[I(total)] of the resistive and reactive current, where

I(total)= Square root of [I(resistive)squared] + [I(reactive)squared]

This post was edited by mm11 on Fri, Jan 25, 13 at 13:49


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RE: Verifying POCO meter

Thanks, that was my understanding. The fact is that we all pay for the crappy power factor CFl lamps, linear fluorescent ballasts, and other junk that is being foisted upon residential customers.


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RE: Verifying POCO meter

" The fact is that we all pay for the crappy power factor CFl lamps, linear fluorescent ballasts, and other junk that is being foisted upon residential customers."

WRONG.

We pay only for real dissipated power.

Watt-hours.

Incandescent lighting and electric heating (air and water) are about the only purely resistive loads in a residential setting.

Every motor in your house has a crappy power factor and you DO NOT PAY anything for it.

You only pay for amps * volts * power factor (REAL dissipated power) since that is the only thing the meter registers.

That is why the various power factor correctors that appear to reduce current in a residential system do NOT WORK.
They are a SCAM.

Watt-hour meters measure real, in phase, dissipated power.
They do not respond to VARs or reactive power.

The only impact power power factor has on a residential bill is the tiny amount dissipated in the conductors by the higher current flowing back and forth each cycle as reactive power.

This post was edited by brickeyee on Fri, Jan 25, 13 at 14:32


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RE: Verifying POCO meter

I understand what you wrote. What I meant in the passage that you quoted is that every time a poor power factor device is installed in a place where power factor is not taken in to account in billing, the POCO is delivering more power than it would have to if a slightly more expensive, quality device were installed. The POCO has to recoup its costs somehow and that will be through higher rates for everyone.

That means that although these wonderful CFLs that are sold to households cut the metered usage for that device by a factor of 4, since the power factor is probably little better than 0.65. That means that the actual power used is only cut by a factor of 2.6. If you compare that to a commercial/industrial CF, the power factor will be 0.9 or greater.

I just can't escape the feeling that the public is being misled to some extent. That is despite the fact that the above analysis is oversimplified.

Is this really an issue for the power companies, or does the capacitance and inductance really balance out in residential areas? Maybe the distortion introduced by cheap CFLs is actually beneficial because it balances other devices. I have not seen an analysis that goes beyond hand-waving.


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RE: Verifying POCO meter

The while grid looks very inductive.

This shows as higher losses in distribution lines, requires larger transformers, larger circuits (the VARs must still be generated and delivered).

Capacitor banks are used for transient supression by the POCOs, or if distribution lines start getting long enough to have problems.

Very large users get a break by controlling their power factor.
PC supplies started getting out of hand a while ago so by law they must have a better PF.
The non-sinusoidal current they require was causing a lot of problems (like overloaded neutrals) since the phases did not balance very well).

Having part of the grid go capacitive is a big problem (luckily it rarely occurs).
All those distribution lines are pretty inductive.

Your understanding of dissipated power as it relates to poor power factor is still not correct.

Even with a lousy power factor and parasitic losses (I^2*R in conductors) the CFL is far more efficient than an incandescent.


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RE: Verifying POCO meter

The elite true power from Efergy looks good at first-- and available at good price on ebay. But the video shows no way to measure the voltage. So it's usefulness for comparing to another meter is limited.

Here is a link that might be useful: Installation


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RE: Verifying meter

The blueline innovations products clamp around the POCO meter. I do not know if this can accomplish what I desire. But the POCO here absolutely does not tolerate any attachments to the meter. And they make random checks.


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RE: Verifying POCO meter

What is not shown in the video for the Efergy unit is that there is a power connection made inside the panel for the 'transmitter'. You can see this in the manual on their website.

BTW: there are two power supplies, one for the transmitter and one for the display.

The clamp-on or otherwise 'mount on' devices are counting the display pulses that the meter produces every 0.1kwh, either when the wheel spins or (with electronic meters) when a light flashes.


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RE: Verifying POCO meter

Further research indicates that Efergy has two products that use displays that appear to be the same. The one that senses voltage is "Elite True Power Meter" and has their model number TPM-NA-1.0. The other one does not measure voltage and apparently assumes 120/240 in the displayed numbers.
I have found no source other than Efergy selling the TPM-NA-1.0. Sometimes other sellers offer better prices or free shipping.


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RE: Verifying POCO meter

If it assumes voltage it is not checking the phase between the voltage and current and is not reading kW-hr but most likely just V-A.


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