# Default emonpi kit calibration? **URL:** \ **Category:** emonPi\ **Tags:** calibration\ **Created:** [9 November 2022 16:29 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803 "2022-11-09T16:29:55Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![aymeric106](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/a/db5fbb/32.png) [@aymeric106](https://community.openenergymonitor.org/u/aymeric106)\ **Post date:** [9 November 2022 16:29 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803/1 "2022-11-09T16:29:55Z")
Hello, I bought an emonpi shield kit, 2 CTs sensors and a AC-AC sensor (eurooo-plug) a few months ago. Now I have a digital counter from my power company so I can compare the emonpi value and the real value i’m charged for. (sort of because i can only see live apparent power consumption) The value I got from emonpi is quite above the real value, especially at high load. I guess it is a calibration issue. I read the calibration page in the guide, but now my setup is installed, it is quite difficult to remove everything. **Is there some value I should change in the config files with the defaut CT and AC-AC adaptator that were delivered to me ?** here’s the comparison between the use feed and the value I get from my counter. Again, not srictly the same, the PAPP is the apparent power consomption (in VA units), but it shouldn’t be lower the emonpi (in W unit) Thank you ![image](https://community.openenergymonitor.org/uploads/default/original/3X/c/2/c222f010039e31687aa6252aa4ea903f4e3e3769.png) ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [9 November 2022 16:51 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803/2 "2022-11-09T16:51:23Z")
It’s going to be a very long process of trial and error to get the calibration anywhere near correct if you can’t run controlled tests. What exactly is LINKY PAPP? - I take it, it is from your supplier’s meter? What you need to do is first is adjust the calibration constant for voltage in the “emon” front end so that the correct voltage is reported. This is probably the main source of error as the EU a.c. adapter has a different calibration to the UK one. Then, using high power resistive loads, adjust the current calibration so that the current reported agrees with your supplier’s meter - if that gives you access to the current, else you must compute it from the voltage & power/energy. Finally, you’ll need to adjust the phase calibration so that real (active) power/energy agree. If you have a sufficiently modern sketch in the “emon” front end, you can adjust the calibration via emonCMS. I’ve lost track of what is pre-loaded now by The Shop (because I’m working on one or two versions ahead 😀 ). ---
**Author:** ![borpin](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/borpin/32/193_2.png) [@borpin](https://community.openenergymonitor.org/u/borpin)\ **Post date:** [9 November 2022 17:11 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803/3 "2022-11-09T17:11:45Z")
> [@aymeric106](#): > > The value I got from emonpi is quite above the real value, especially at high load. > I guess it is a calibration issue. Yes, the CT is always an estimation. Personally I multiply the incoming CT Input so it matches (in my case) the pulse input. Scale factor is currently 0.9438 on my main supply. Last time I checked it was less than 1% difference IIRC. It is simpler than Robert’s way 🙂 [edit] You can easily work out what the scal factor needs to be on that graph page. In the box below, simply add the scale factor until it fits. ---
**Author:** ![aymeric106](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/a/db5fbb/32.png) [@aymeric106](https://community.openenergymonitor.org/u/aymeric106)\ **Post date:** [9 November 2022 18:10 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803/4 "2022-11-09T18:10:35Z")
> [@Robert.Wall](#): > > What exactly is LINKY PAPP? - I take it, it is from your supplier’s meter? Yes apparent power. Sadly, intensity, voltage and … active power are not available > [@](#): > > What you need to do is first is adjust the calibration constant for voltage in the “emon” front end so that the correct voltage is reported. This is probably the main source of error as the EU a.c. adapter has a different calibration to the UK one. Then, using high power resistive loads, adjust the current calibration so that the current reported agrees with your supplier’s meter - if that gives you access to the current, else you must compute it from the voltage & power/energy. Finally, you’ll need to adjust the phase calibration so that real (active) power/energy agree. I don’t think I can do that without intensity, voltage or active power values unless I unhook everything and put it on a bench > [@](#): > > If you have a sufficiently modern sketch in the “emon” front end, you can adjust the calibration via emonCMS. You mean by editing emonhub.conf via emoncms or are you refering to something else ? Thank you ---
**Author:** ![aymeric106](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/a/db5fbb/32.png) [@aymeric106](https://community.openenergymonitor.org/u/aymeric106)\ **Post date:** [9 November 2022 18:17 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803/5 "2022-11-09T18:17:27Z")
By comparing use\_kwh and my actual metering i see a 0.92 factor. By apply that to my graph, they almost align (on the high value). So I guess I’ll do that. Do you apply in emonhub.conf like that ? [[5]] nodename = emonpi [[[rx]]] names = power1,power2,power1pluspower2,vrms,t1,t2,t3,t4,t5,t6,pulsecount datacodes = h, h, h, h, h, h, h, h, h, h, L scales = **0.92** ,1,1,0.01,0.1,0.1,0.1,0.1,0.1,0.1,1 units = W,W,W,V,C,C,C,C,C,C,p or through the input/feed configuration ? Aymeric ---
**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\ **Post date:** [9 November 2022 19:02 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803/6 "2022-11-09T19:02:18Z")
You can do either, but I favour doing the correction as close to the source of the data as possible - in emonHub. But there’s no guarantee that doing what you are proposing will give correct values at different loads, especially small loads that often have a very poor power factor. > [@aymeric106](#): > > You mean by editing emonhub.conf via emoncms or are you refering to something else ? I was referring to the Serial Monitor in Admin. (emonCMS). ---
**Author:** ![borpin](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/borpin/32/193_2.png) [@borpin](https://community.openenergymonitor.org/u/borpin)\ **Post date:** [9 November 2022 20:18 UTC](https://community.openenergymonitor.org/t/default-emonpi-kit-calibration/21803/7 "2022-11-09T20:18:30Z")
> [@aymeric106](#): > > Do you apply in emonhub.conf like that ? No I do it on the input processing.