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jeanphi500 asked

ET112 grid meter measurement shows "disconnected" while it seems it's not

Hi

I'm running an ESS setup where the grid power information is sent from the ET112 grid meter back to a Victron Multiplus II 5000.
Everything seems to run rather fine but the console keeps showing that my grid meter is disconnected.. while the battery seems to charge ok.
1652344075327.png

Now looking at the realtime display in VRM the grid value fluctuates really a lot.
Sometimes I see it saying that the net is giving 2000W while it's just the opposite, it's being fed with 4000... Then 10 seconds later it shows that it's being fed with 4000 then 10s later that turns to 10W then positive again.. That grid meter box corresponds really to nothing.
I have a homewizard connected to my (official) smartmeter and that one is perfeclty smooth and shows the expected values (same for another meter on the same output, connected to my Solarlog. That one shows correct values).

Any idea what could be the issue? I have about 5m of CAT5 UTP cable between the ET112 and the Multiplus.

ESS
1652344075327.png (49.0 KiB)
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Jason - UK avatar image Jason - UK commented ·

IM currently getting a similar situation with my 40A current sensor. It keeps connecting then disconnecting from the remote console yet the data is still being used to calculate the AC loads.

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jeanphi500 avatar image jeanphi500 Jason - UK commented ·

Yes and now for example it shows connected and gives stable measurements..
What is annoying is that it's difficult to decide whether the console then does not reflect the real state or if there is a real issue..

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Jason - UK avatar image Jason - UK jeanphi500 commented ·
@jeanphi500 My thoughts the same.
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Jason - UK answered ·

@jeanphi500 there are lots of posts about this issue and they all relate to the high latency of the ET112 energy meters being slow to provide the correct information to the GX device. I have a ET112 but i have not wired it is because of this issue. I have kept with the 100A Victron CT sensor, which appears to be less accurate but is much more responsive.

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Jason - UK avatar image Jason - UK commented ·

I'd try the 100A sensor and see what that does but I think you might lost your 'AC Loads' on AC in1 data on the VRM portal. The only time I was able to see my AC Loads on ACin1 was for the moment i had the ET112 connected.inkedwhatsapp-image-2022-05-04-at-112145-am-1-li.jpg

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jeanphi500 avatar image jeanphi500 commented ·

Hi Jason!

Yep I've been reading the posts about the latency of the Multiplus to react to sudden changes of load indeed. Victron themselves seem to aknowledge that. Is this what you point to?


But I'm not sure it is completely related. Even with latency, why would I get readings that are wrong like the ones I reported in the comment. In the example above I am sure the grid was being fed with 5000+W for at least 5 min already. Why did the reading of the ET112 report 200W ? And why does it report in the console that it's not connected? Pity for me I did not find these threads before .. I've been spending some time rewiring a part of my fuse box to accomodate the ET112... A CT would have been so much easier to install :-/

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Jason - UK avatar image Jason - UK jeanphi500 commented ·
@jeanphi500 I had the ET112 fitting in a temporary arrangement after the main incoming 100A fuse because I didn't have a spare way on my panel but when it was connected, it appear to be over stating the export to the grid for a few seconds then under stating the value, for example, my PV inverter showed 3300w generation, ACout1 loads 300w, therefore you would think 3000w going into the inverter, and with no charging going on because the battery was full, you would expect about 3000w being exported to the grid but it was bouncing around between -4500w and -1000w as the clouds came over and then went away, yet the PV inverter didn't go above 3400w of generation and it didn't go below 1500w of generation. The ET112 data appeared to have about a 10sec latency and the Multiplus, assumed because of the late information was stating odd values on the Grid value that were outside what was possible.
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jeanphi500 avatar image jeanphi500 Jason - UK commented ·
I'm not sure the 100A one will work in my case.. It is then rated 100A but I read it is limited to 32A max.

I wonder why that is, is the scale in the Victron then limited to 0-16 mA (as for 50mA/3) ?
I have 50A on my main line..

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Jason - UK avatar image Jason - UK jeanphi500 commented ·

https://www.ebay.co.uk/itm/264601632463

It is the same CT sensor, just without the £20 Victron name written on the box.

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Jason - UK avatar image Jason - UK jeanphi500 commented ·
In short, I feel the ET112 is not suitable if you want a accurate and reavtive ESS system but maybe better off being fitted to the output of a PV inverter to better calculate the difference between loads and PV input which doesn't have a direct affect on the ESS but can provide better PV generation data in VRM. Thinking about it, maybe its the rapid bouncing back and forth from import then export that causes the ET112 to miss-report information? That would make sense.
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shaneyake avatar image shaneyake Jason - UK commented ·

There is 2 diffrent measurements to talk about.

Instantaneous power in Watts (W), which is displayed in the grid block on a GX.

Total power in Kilowatt Hour (kWh) which is displayed on VRM as historical data.

The ET112 is pretty bang on with the kWh but can be delayed or laggy in displaying Watts but will give a more accurate reading.

The CT is way more responsive but isn't great at the kWh and not very precise with the Watt.

When using an ET112 meter the kWh counters are in the meter and running at sampling rate. Rapid import/export isn't a problem, it will have a hard time controlling the inverter to deal with those spikes but won't have a problem counting total energy transfer.

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jeanphi500 avatar image jeanphi500 shaneyake commented ·
That's true but the sole reason the meter is there is to feedback the instantaneous power usage to the inverter. The fastest that loop is the best the inverter can follow the rapid changes of the load/feedin.

Energy readings are nice to have but I'm not sure they play any role in the control loop.
And I can understand the issue (being myself a electrical engineer working on instruments). Anything that has to do with readings involving software and external links is considered slow. Feedback time cannot be guaranteed. While clearly with CT the current is a direct input and the reading of the value happens directly in the inverter.

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jeanphi500 answered ·

Here are 2 screenshots taken 10 seconds apart

The first one with a bad reading:
1652344846055.png


Second one with the correct one

1652344900943.png



1652344846055.png (43.5 KiB)
1652344900943.png (35.0 KiB)
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jeanphi500 answered ·

Hi @Jason I just ordered the SCT013. I'll post results when I have it installed. Thanks for the help!

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jeanphi500 answered ·

CT received on Saturday and installed at once.
VRM readings are now stable and everything seems in order. I'll keep that solution :)

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Jason - UK avatar image Jason - UK commented ·
Happy days. Good to hear. I had the same learning curve so I feel your pain. lol
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