Real vs Apparent vs Reactive Power & why things dont add up in the app

[natbesh]

Do some reading & learn about Real vs Apparent vs Reactive AC power – it’ll do your head in, but just make sure you get the basic gist of it.

The key thing is that reactive power isnt really doing anything, it comes into the load & then goes back out – so you dont pay for it (check your local rules etc etc), however its flowing & it gets measured.

Now – the Vue2 measures Apparent power on each of the 16 sensors – which includes that fake Reactive power. Things like an air conditioner have HUGE amounts of reactive power when in standby. My A/C unit shows 300W of power!!! but its all reactive.

The Vue2 measures Real power on the 3 main CT’s – so it removes the reactive power from its calculations and shows what you’re actually using & being charged for.

So…. Your main power readings from your incoming supply will be very accurate, however all the other circuits may be somewhat inaccurate depending on what is running on them. Thats why the things dont add up & there’s magical “free” feed-in power from somewhere. There’s likely a load with high reactive power somewhere on the smaller CT’s.

So if something looks like its consuming heaps of power – yet there’s nothing on the main power CT’s, trust the main power CT’s.
Culprits are switchmode power supplies, induction motors… anything that has a low “power factor”.

Hope that helps others!

[scrambler]

Do you know for a fact that the load CTS do not account for the power factor? If so from where/ whom?

Because I was told initially that they did measure power factor to measure real power.

[natbesh]

yes i’m 100% positive – i went & purchased the instrumentation to test it.

The test equipment is a few hundred $, it taps the voltage on each of the 3 phases and clamps each phase as required, and shows active/reactive power on each phase.
The circuits I was testing had 300W of pure reactive power. The emporia was measuring “300W” on the sub circuits, but “20W” on the mains side with a balance of “-280W”, this corresponded to the test equipment and also the meter on the grid.

Thinking of the internal hardware, it would be hard to detect & setup 16 ports and check the phase angles & check them all.

 

[scrambler]

That is disappointing to hear then

[djwakelee]

My experience is different.  I have all circuits monitored, and zero balance (or so).  At times there are plenty of inductive loads (AC compressor, pool pumps, forced air blower), which greatly exceed any 1.0 power factor devices.  The math always adds up with the individual circuits, balance, and mains – within that 2% tolerance.  If the circuits were only measuring apparent power (VA), things would be way off.

The original Vue 1 only measured VA (apparent power), and was horribly inaccurate for non-resistive loads.  The Vue2 is spec’d to measure true power, and I have no reason to believe this is only on the mains.  My observations do not support that conclusion at all.

Would like to hear from Emporia regarding this.

[scrambler]

Confused …

[djwakelee]

From Emporia chat…

“we measure apparent and real power, and use real power on all circuits”

The poster who theorized VA measurement on the 16 circuits did mention 3 phase – so maybe there is some bug there.  But with 120V/240V split phase in the US, I see accurate W (real power) for the 16 circuits and mains with mixed power factor loads – as confirmed by Emporia.

[scrambler]

@natbesh, may be time to dig deeper on this …

[natbesh]

yep – 3 phase power in my readings & results.

Not much more i can dig into or do – I look at the App & it says 300W (100W x 3), i check the equipment it says next to nothing.. the mains say next to nothing… My grid cancelling inverters that use CT’s (2 different models) both say next to nothing.

So thats test equipment, the equipment manufacturer (300W load), 2 different inverters, the view mains CT all giving the same results… then the Vue load CTs giving different results…

[djwakelee]

For 3 phase, understand the Vue2 is only compatible with Y (Wye) type configuration with neutral.  If your 3 phase is Delta type or without neutral, it wouldn’t work properly.  The majority of people use the Vue2 with residential split phase 240V/120V in the US (and 240V single phase in other countries), in which case it correctly measures real power on all circuits.  3 phase commercial setups are not as popular, but are supposed to be supported if up to 415Y/240VAC Y type with nuetral.  Perhaps some other folks with that setup can chime in and report if they see in discrepancies in operation with 3 phase setups (as well as what country).

You may want to verify your 3 phase hookup, and/or contact Emporia chat.  They don’t seem to monitor this forum as much as they used to.

• This reply was modified 2 years, 6 months ago by djwakelee.

[Scott9]

I can’t get a CT on my incoming mains but I measure the six 240v split phase circuits from the service entrance using two Vue2s. So far, I have three data points with daily power running from 41 KWH to 107 KWH and the total Vue2 power was always within 1 KWH of the Duke Power daily numbers. Plenty good enough IMO.

But I did wonder how the Vue2 correctly associated the A and B phase voltages with the phase/branch currents? I suppose the voltages should be close (except for sign) so maybe it doesn’t matter.

But three phase is a whole different deal; if voltages are not correctly associated with leg currents there could be really odd results for power at the mains.

[ArubaUser]

I experience the exact same thing as topic owner! I live on Aruba, we have 127/220V 3 phase here. All my AC’s show huge consumption in the app when in standby: I have several split units, varying from 80 to 300 watt according to the app, in standby. When I add up the shown usage of all my AC’s the total is much higher than what the main is showing (which indeed DOES seem to show real power). So that’s the first indication that topic starter is right.

Then I ran a test, I have a simple ‘killawatt’ wattmeter, which has a Watt/VA switch (real vs apparent). So I connected my dryer, it showed 600 in the app but 400 watt in my killawatt meter in ‘watt’ mode. Then I switched the meter to “VA mode” (= apparent power) and it showed 600!

So in conclusion, yes, topic starter seems right. The app (at least in my country) seems to measure apparent power on the 16 sensors and real power on the mains.

Hopefully somebody from Emporia can jump in and explain this

• This reply was modified 2 years, 3 months ago by ArubaUser.
• This reply was modified 2 years, 3 months ago by ArubaUser.
• This reply was modified 2 years, 3 months ago by ArubaUser.
• This reply was modified 2 years, 3 months ago by ArubaUser.

[ArubaUser]

I was wondering what 3 phase power you exactly have? Are there 3 phase users who do not have this problem? So to describe the problem again, on (some?) 3 phase installations the emporia seems to measure the apparent power. This makes a difference on devices that have huge reactive power flows, like airconditioners, tumble dryers, in general devices with a motor. For example my water heater (for tea) only has a heating element, no motor. It shows about 1600 watt, my killowatt meter shows VA=Watt and indeed, the emporia shows the same. But for devices where my killawatt shows a substantial difference between VA and Watt (mostly devices with a motor), the Emporia correlates wih the VA, not with the Watts…

As this is a problem on all locations that we’ve tested in my country (Aruba) I’m pretty sure this must be a bigger problem. For example big parts of Mexico and Brazil use the exact same 127/220 3 phase so I’m expecting people in these countries to have the same problems. But I was wondering if it happens on other 3 phase configurations  too?

• This reply was modified 2 years, 1 month ago by ArubaUser.

[ArubaUser]

I was wondering what 3 phase power you exactly have? Are there 3 phase users who do not have this problem? So to describe the problem again, on (some?) 3 phase installations the emporia seems to measure the apparent power. This makes a difference on devices that have huge reactive power flows, like airconditioners, tumble dryers, in general devices with a motor. For example my water heater (for tea) consumers about 1600 watt, my killowatt meter shows VA=Watt and indeed, the emporia shows the same. But for devices where my killawatt shows a substantial difference between VA and Watt, the Emporia correlates wih the VA, not with the Watts…

As this is a problem on all locations that we’ve tested in my country (Aruba) I’m pretty sure this must be a bigger problem. For example big parts of Mexico and Brazil use the exact same 127/220 3 phase so I’m expecting people in these countries to have the same problems. But I was wondering if it happens on other 3 phase configurations  too?

[John Polasek]

I am making some assumptions here, but it sounds like the confusion comes in when considering 3 phase equipment that uses 3 individual CTs for a large load.  The VUE does not recognize that they are part of a single device and simply adds the three individual current times voltage values together… which if the equipment is “Y” connected (all 3 phases tied to a common return wire) delivers the correct result.  However, because in 2 phase circuits, the phases are displaced 120 degrees from each other, in a “delta” wired motor with no tie to the neutral, a lot of current simply runs around in circles without actually being used for power, but the CTs don’t know that and so give inaccurate readings.  And the only way to “fix” it would be for Emporia to enable “grouping” the individual CTs in the app in order for them to employ the same calculations they do on the mains (which they DO know are out of phase with one another)… all of the single phase loads (plugs, lights and the like) that come off one phase and go back to a neutral will be completely accurate.

[ArubaUser]

Still no update on this? It’s so annoying, this is a wonderful device, we’d love to start selling it in our country but as long as it doesn’t work correctly we just can’t sell this  …

• This reply was modified 2 years ago by ArubaUser.

[ArubaUser]

So I bought this cheap unit from Amazon https://www.amazon.com/gp/aw/d/B0919LV66F and it actually works. It tells me 4 watt for my AC in standby vs 95 watt according Emporia. At max it tells me 1.77kwp vs 1.91 according to the Emporia.

 

Of course this unit has way less functionality than the Emporia it’s not what I’m looking for, I need wifi. But if they can do it then Emporia should fix their unit, damn

[scrambler]

Can this Amazon unit record overtime, and if so at what interval, for how long, and how do you download the data?

[ArubaUser]

No, it’s an extremely basic device. I merely pointed it out to show that this thing actually works. I’ve been comparing data so far for 3 AC units:

Unit 1: Emporia shows 70 watt in standby (no way that that’s possible), the ‘amazon unit’ shows 1 watt in standby (which must be correct). On max power the difference also is about 70-100 watt higher for the emporia.

Unit 2: Emporia shows about 70 watt in standby (cant be correct), amazon unit shows 4 watt (makes sense). Again, also on max power the difference is about 70-150 watt higher for the emporia.

Unit 3: Emporia shows only 19 watt in standby, amazon unit shows 4 watt. On max power the result is about 10-50 watt

Haven’t checked out if this difference is just the ‘reactive’ power …

• This reply was modified 1 year, 8 months ago by ArubaUser.

[ArubaUser]

Going to do more measurements the coming days, hopefully they’ll give Emporia a hint on what the problem is. I just wish they’d fix their unit. I mean 70 watt difference in standby, that’s 1.7 kwh a day, it pretty much renders the device useless. Which is a shame because it’s really a wonderful device otherwise.

[Peter]

So, with the 127Y220 3 phase power, are these all 220 appliances? Or single phase units running on 127 volts?

If they are 220Volt units, then you should only be using 1 CT with a multiplier. You cannot use two CTs and add.

[ArubaUser]

Hi, well I think most (or all?) of the devices i have that have high reactive power, like my airconditioners, are 220V devices. So yes, these are on 2 fase lines. I’ve tried both with 1 CT and multiplier and two multipliers, it’s always the same.

So my conclusion after doing some more measurements with that cheap amazon device that actually DOES correctly measure only REAL power, is that a workaround could be, for most of my problems, if we could just subtract a value per CT. I mean the difference seems to be roughly the same between the airconditioner being off, and being under load. For example I have a few airconditioners where that difference is always about 140 watt: it shows about 140 watt in standby and on load it’s about 140 watt too high. So if Emporia can’t fix this problem, at least an offset to subtract per CT would be a great workaround and would make this device much more usable on 3 phase situations.

• This reply was modified 1 year, 6 months ago by ArubaUser.
• This reply was modified 1 year, 6 months ago by ArubaUser.

[Thorgard]

I have 4 emporia vue 2.  I am in Europe with 3x400V+neutral.  All my single phase device are then phase to neutral … but unfortunatly, Emporia is measuring apparent power and not active power.

[ArubaUser]

Hey Thorgard, thank you so much for this post!! So now we have confirmed the problem on 3 phase 127/220V and 230/400V.

I’m really hoping Emporia can do something about it. Or at least add that simple ‘subtract feature’ that I just mentioned in my previous post, that would be a great workaround for a lot of situations.

[Jean-Luc]

Same issue here.

The issue is very well described in the first post: the apparent power seems to be measured/calculated/displayed, not the active power.

It’s not just a question of subtraction: the Rogowski coil measure the current, but has no clue about the voltage.  What the Vue seems to do is to output the apparent power (i.e. the product of current RMS and voltage RMS, which is basically constant). What the Vue should do is multiply the current with voltage (including phase) before averaging. The problem is that there are 3 phases, so it become a bit more tricky to choose which phase to multiply.

So what should be done is to be able to associate each coil with a phase in the configuration pannel, so that the computation would become correct (computing the active power). We could argue that this is slightly more complex to configure and to explain in the user manual, but that’s the only way to monitor something valuable. For devices having a small cosphi, the readout is otherwise totally wrong and the Vue becomes pretty useless. This is really a pitty because the hardware is really nice !

[djwakelee]

This is also being covered in another thread, but it may be by design.  3-phase (in the US) is typically for commercial customers, and that is billed by the utility as VA (apparent power).   Residential power is billed in W (real power), and the Vue 2 does this properly for split phase 120/240V.

I’m not sure why Emporia does not respond to this forum often, but you may get better results by chatting with them.  It may be by design, and not actually a bug.  The product seems very US centric – they may not have considered that other countries have 3-phase residential power and real power billing.

[AC_DC]

Hi,

Emporia writes the following on their FAQ page:

“… The Gen 2 samples voltage and measurement channels at approximately 24,000 samples per second. Twice per second, the Gen 2 uses these measurements to calculate root mean square averages for each of the voltage channels, and then intelligently pairs current channels with the correct voltage channel to calculate and report REAL power for each of the 19 CT’s in the app….”
see: https://help.emporiaenergy.com/hc/en-us/articles/4408877035415-How-does-it-work-

At another place one can read:

“… Through the wire harness, we’ll be able to detect voltage as well as other detailed power related information like phase, frequency and offset. We use those values to provide the most accurate measurements possible although not all are shown in the app at the moment…”
see: https://help.emporiaenergy.com/hc/en-us/articles/4408885421463-How-the-wire-harness-works

I therefore assume that the assignment of current sensors and corresponding phase is made automatically by the internal software. For small amounts of apparent power, the algorithm works quite reliably (Current and voltage have only a small phase shift) , but for large amounts of apparent power and thus very large phase shifts between current and voltage, it obviously no longer works. In this case, an option for manual assignment of current sensor and phase in the software would be desirable.

I am in contact with Emporia customer service and will report my results.

 

[djwakelee]

What part about the approach is it that you feel doesn’t work?  They measure voltage, current, and phase angle – which is all used for real power determination.  Believe this has been shown to work well for everyone with split phase 120/240V setups (or 230/240V single phase), but there are some people saying there is an issue with 3 phase.  Is that your scenario, or do you feel something else is amiss?

• This reply was modified 1 year, 3 months ago by djwakelee.

[TonyJr]

Hello,

I have earlier today installed a Vue Gen 2 into a commercial 3 phase distribution board in the UK, with the same kind of result, after only a few hours.

Here is a screenshot of the kWh on day view, for you to see. This is about 7 hours worth of data.

230V/415V 3 Phase with N. This panel has all 3 phase circuits, but a sub-panel contains a mixture of single and 3 phase circuits.

It really would be handy to be able to group the CTs for a 3 phase circuit in to one logical sensor.

Notice D1 and D4 have sensed current flow, however nothing is connected to the socket on the panel and the large lathe has not been operated (fully isolated). D2 and D3 have also not been used, but sense nothing. These are all adjacent circuits.

All circuits are monitored.

Tony

• This reply was modified 1 year, 3 months ago by TonyJr. Reason: State that all circuits are monitored

[marcogtt]

Hello, Italian customer here 3×400 N distributed. Same issue on VFD 3phase load (heatpump compressor ) i hava a solid 3x100w ghost power recorded and balanced back from the app .

 

I’m also having a lot of issues with the Solar/akku circuit that is also displaying weird figures, also in that case i have a frequency converter from DC to AC (3phase) i guess that is the issue as well…

[ArubaUser]

So, did anyone find a solution to this problem? According to the Emporia employee in the “EU 3 phase installation setup” thread there is no bug. It should work normally. However it just doesn’t for me nor for any of my friends here in Aruba, I have several who tried it too, all with their own devices and houses, everytime the same conclusion: the emporia incorrectly registers a 50-150 watt ‘ghost’ usage for Airconditioners, where a simple amp clamp doesn’t register that (and these are high SEER units, so it’s just impossible in the first place).

And it also doesn’t seem to work for the people here in this thread. What am I missing? Going to contact Emporia chat monday again to see what they say about this issue. I would just really LOVE to have my unit work correctly.

BTW, it also registers a ghost result for my solar panels, the device seems to think they’re generating energy at night. I have two 3.6 kwp inverters and both of them are generating 15 watts in the night, so that’s 30 watts of ghost solar energy that the device reports. Not sure if this has anything to do with the ghost airco energy, but still wanted to report it here.

• This reply was modified 6 months ago by ArubaUser.
• This reply was modified 6 months ago by ArubaUser.

[ArubaUser]

So a recap of the last 2 days: I chatted with Emporia chat (Joe). Joe was extremely helpful and willing to guide me through some experiments. He seemed to think that the problem was that some clamps were being locked to the wrong channel (=phase). He made some changes which split the ‘ghost usage’ in 2. But I think his reasoning was at least partly incorrect. What he made me do is made me measure things with an AMP meter. However AMP meters don’t measure real power, so of course it showed up high (0.5 amp) for my airco in standby too, just like the emporia. HOWEVER I now just tested with this device: https://www.amazon.com/Current-Amperage-Voltmeter-Multimeter-Transformer/dp/B07JB9B2QL/ which is a simple clamp meter that also measures the power factor and THIS is where it all goes wrong. In standby this device also sees about 0.5 amp for my airco, HOWEVER it shows a power factor of 0.02 in standby!!! And thus only a real power of just a few watts …

Also when the air conditioner powers on and usage is over 1000 watts, then the amazon device shows a power factor of 0.99 and indeed, emporia measurement is then very close to that amazon device management (since VA is almost the same as watts in this case)

So in short, both AMP meters as the emporia indeed seem to measure apparent power instead of real power. Going to chat to emporia chat again, but to me at least this shows indeed that this is the problem

• This reply was modified 6 months ago by ArubaUser.

[emporiacs]

Hi,

For accuracy issues, please continue to contact Customer Support directly s0 we can thoroughly investigate and help with each individual case.

Thank you for your patience!

[ArubaUser]

So I’ve bought some ‘homewizard’ SD230 meters single phase, which I connected to some airco’s. The great thing is that I FINALLY get to see the real standby power that’s being used (8 watt insteadby instead of the 95 watt that the VUE2 registers) AND have it logged online!!. However the bad things are of course that it needs free double slots in my breaker box, it’s WAY more expensive and worst of all, only saves data on 15 minutes basis. So again, really not what I’m looking for but I’m getting desperate here 🙂 Emporia keeps silent on the issue, REALLY hoping that they’re working hard on a fix. The VUE2 is just unbeatable in terms of features. But right now also unusable for 3 phase setups out of the USA.

PLEASE FIX THIS EMPORIA I NEED THIS IN MY LIFE !!! 🙂

[emporiacs]

Hi ArubaUser,

Thanks for this feedback. We know for certain that many customers in Europe and Caribbean in 3 phase have the product working as expected. Based on your descriptions, our inkling is to ensure there isn’t something incorrect installation. Please contact customer support again directly and we’ll be happy to continue diagnosing this with you. Thanks for your patience.

[ArubaUser]

Ok had another long chat with Emporia and they said they are aware of the issue: “Its the way we see and lock 3 phase and there’s no easy way to fix that” was the response. There’s hope for a fix in the future though “we are always making changes to the database so it will get fixed one way another but dont know how long” so let’s hope Emporia can figure this out. I really would love for this device to work in my country (aruba)

[mako]

Another UK 3-Phase + N customer here with 200W ghost load appearing on circuits with air source heat pumps when they are in standby. Looking forward to a fix for this Emporia dev team.

[emporiacs]

Hi,

Please contact support and so we can help confirm the configuration is correct.

[SamSavageSpeed]

Hello,
Did you found a fix for this issue ?

[ArubaUser]

I do wonder if this issue still exists on Vue gen 3? I’ve actually ordered one, eager to find out …

[emporiacs]

We measure both, apparent and real power but we report real power only in the app, as that will be what the utility company bills you for energy.

[Author]

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