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18kpv CT Power Offset

Justdr5

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Joined
May 20, 2021
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The values for grid consumption are way off reality in my system. I see L1=3.69A and L2=5.01A which should translate to around 1k W. I do see a variable labelled as CT power offset but I did not find anything in the manual on this. I am guessing I need to change this value to offset the currently displayed value to the correct ones but wanted to check in with this group before doing so. Thanks.




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one of them my be reversed? the CT offset is in the "0-100 watts" range
Just double checked, they seem to be in the right direction. Also, from the maintenance dashboard it shows the range is -1000,1000. But maybe it is -100,100?

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Can you unclamp one of the CTs from the inputs, then evaluate what your meter says vs the 18kpv for the remaining input?

Then re-attach the other CT, detach the first one, and do the same?

This gives us some more troubleshooting data that might explain the problem. Also - read your settings and tell us if the CT power offset is set to anything right now
 
Are you accounting for active power vs apparent power when comparing the two? Depends on how much the house is pulling/pushing.

If you just take current measurements and no accounting for voltage/shift between current and voltage you are doing apparent power
 
Can you unclamp one of the CTs from the inputs, then evaluate what your meter says vs the 18kpv for the remaining input?

Then re-attach the other CT, detach the first one, and do the same?

This gives us some more troubleshooting data that might explain the problem. Also - read your settings and tell us if the CT power offset is set to anything right now
Will do. Can't actually measure it now as the sun is up=)
 
Are you accounting for active power vs apparent power when comparing the two? Depends on how much the house is pulling/pushing.

If you just take current measurements and no accounting for voltage/shift between current and voltage you are doing apparent power
yes I believe the current clamp does not know voltage so it would be considered "apparent current" if there was such a thing. That being said, taking the current read and multiplying by voltage should get me in the neighborhood right? I am seeing 250W on the inverter screen but I am drawing ~1k ish in reality. I also confirmed with my transfer switch / sense device and they are all around ~1k watt draw. I spoke with Signature and they changed my CT power offset value to -40. I will not know if this had a positive impact until the sun goes down (and the battery runs low). Thanks for your response.
 
yes I believe the current clamp does not know voltage so it would be considered "apparent current" if there was such a thing.

It's just RMS current, it's real. The question is how much power is going through them

That being said, taking the current read and multiplying by voltage should get me in the neighborhood right?

Depends on what the loads are. If all the load is from barely corrected or uncorrected power supplies (like bunch of DC wall warts) then you can easily be off by 30-40%. Same if it's a bunch of motor loads (both AC motors and inverter-driven/ECM motors with a power conversion stage in front)

I am seeing 250W on the inverter screen but I am drawing ~1k ish in reality. I also confirmed with my transfer switch / sense device and they are all around ~1k watt draw. I spoke with Signature and they changed my CT power offset value to -40. I will not know if this had a positive impact until the sun goes down (and the battery runs low). Thanks for your response.

OK if you have other things measuring 1kW power (kW is always active by definition) then there is something wrong.
 
Firmware up-to-date. 6 gauge wire isn't sufficient for 50A?
#6 is fine, I think it just looks like a clown shoe situation sitting inside a CT intended for 200A

Yeah this confused me as well. Going to hunt around as the offset metric info wasn't included in the manual. Thanks.
If they had documentation or tooltip explaining what that setting mathematically does, life would be easier. Maybe ping one of the EG4 folks.

There is also the possibility that one or both of the CTs is just busted, some of the suggestions upthread on connecting only one or the other would help narrow that down.
 
So tonight I had a heater running plus my normal ~1k draw for a total of ~5k. The 18kpv shows 1600W. I also pulled each CT off 1 at a time and the power draw changed to ~800W total when taking off the L1 CT and ~800W when taking off the L2 CT. The CT Power offset seemed to have no affect on this value as I tried switching it to 0 and back to the -40 that SS suggested.

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Is there a setting for turns ratio? Is the ratio on the CTs correct?

You can also do something dumb and make 3 turns within each one with your #6. The CTs can handle 200A so maybe it’s safe.
 
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