Hi, I need some help.
I've just received my emontx3 and trying to understand the outputs.
I'm using 3 CTs for 3 phase power and a 9Vac adapter (Oz).
Firstly, do I have to update the emonTx to use this sketch emonTxV3_3Phase_Voltage.ino instead of the default one on the unit?
Secondly, my real voltage is around 246V however the emontx is showing around 236V.
Do I need to change the sketch eg line 110 double Vcal = 276.9 ?
My sample output:
10 39 0 4 255 84 0 0 0 65 92 0 0
10 41 0 255 254 75 0 0 0 15 92 0 0
10 41 0 250 254 91 0 0 0 73 92 0 0
10 44 0 241 254 85 0 0 0 46 92 0 0
10 41 0 254 254 97 0 0 0 15 92 0 0
10 45 0 0 255 96 0 0 0 254 91 0 0
10 74 0 255 254 20 0 0 0 2 92 0 0
10 78 0 5 255 20 0 0 0 30 92 0 0
10 77 0 254 254 20 0 0 0 44 92 0 0
10 76 0 242 254 20 0 0 0 234 91 0 0
thank you.
Re: 3 phase sketch
Hi,
The default sketch is not suitable for 3-phase system. You have to change it and then to calibrate your Tx.
Please read the building blocks to understand how 3 phase can be measured with an EmonTx.
http://openenergymonitor.org/emon/buildingblocks/3-phase-power (In particular "Measuring 3-phase power" and "An approximate method to estimate 3-phase power with an unmodified emonTx"
Then read the calibration section of the buildings blocks
http://openenergymonitor.org/emon/buildingblocks/calibration
Also read the comments at the beginning of the emonTxV3_3Phase_Voltage.ino
A lot of information on the forum too : http://openenergymonitor.org/emon/search/node/3%20phase
Eric
Re: 3 phase sketch
"Also read the comments at the beginning of the emonTxV3_3Phase_Voltage.ino"
That is most important. It is critical that the calibration is done in the correct sequence.
Re: 3 phase sketch
great, thank you.
reading http://openenergymonitor.org/emon/buildingblocks/calibration it looks I'll need to change the Vcal using the formula -> New calibration = existing calibration × (correct reading ÷ emonTx reading)
So for me its going to be Vcal = 276.9 x (246 ÷ 236) = 288.63, is that right?
Re: 3 phase sketch
Yes, or you adjust the calibration until you get the same as what you measure with your multimeter.