So, i am working at a project which main focus is to use arduino to monitor two-phase non linear load, like a power mettering system with an option that allows me to see the power factor. The thing is, i dont even know where to start! I've managed to see alot of single-phase measurements, and they seem quite easy. Honestly, i've already seen a two-phase, but it does not calculate the power factor.
To be sure there's no misunderstanding, please make a simple pen-paper drawing explaining what You're talking about. "two-phase" looks odd to me. One face versus GND or another phase makes not much difference.
"Power factor"..... Can You explain what You have in mind? I have a master degree in electrical and electronical stuff and want to make sure I understand You.
Power factor is the difference in phase between the VOLTAGE and the CURRENT, all on the same phase(power circuit).
Paul
HI, @nanhuto
Welcome to the forum.
Have you Googled;
arduino power factor meter
Can you please tell us your electronics, programming, arduino, hardware experience?
Tom... 
I know. Just wanted to make sure OP has the same opinion....
Measuring voltage and current at the same time and so on....
Yes, this is my main idea. For the voltage circuit i would use a optocoupler (4N25), the 2880Ohms resistance will make sure that the led activates whenever the voltage hits 170V, for the 127v, we have 179 at its peak, and for 220v, 311, hence by knowing the delay in activation from the led i will know wheter its hooked up to a 127v AC or 220 AC.
Now, the current part is the trick one. What i have managed to think so far is to use two stc-013, and read its values, knowing that whenever a value hit its peak (it'd be a loop, assuming that the next value is lower, id know it hit that peak), and by knowing the delay it took to hit each peak will make sure that i know the delay, thus transforming it into angles, i will manage to calculate the phase shift between the two currents. What i did not managed to think so far is how will i calculate the real power (which would be a vetorial product between voltage and current). With what i have, i have not been able to think about the voltage delay.
Also, heres a photo of a graph that i've made (i've never tested the circuit, looking forward to).
The grey line is 220v AC, the blue is a 127V AC and the orange is the activation of the 4N25 (which is suposed to happens whenever the hooked up AC hits 170v).
Thanks! Well done!
That TVS diode looks like short circuiting the transformer.
The R2, R3 and C1 looks a bit strange. To what is the lower part of R2/C1 connected? GND?
Yes, its connected to ground. I know that R3 and R2 are voltage dividers, i didnt understand what is C1 doing on the circuit. I just got hold of it over the internet, and i am having a hard time understanding that piece.
For that TVS diode, its just a supression diode that comes within the STC-013 sensor.
Okey, I get it.
You have connected that voltage divider the wrong way. There must be a way for the transformer output to have a circuit, current going out must come back somewhere.
The large voltage should be connected up on R3 and the signal to the analog input should ne tapped between R2 and R3.
Yes, i edited twice cause i've realized 5V was connected also.
That is what i've managed to think outta your answer. Correct me if i am wrong.
Warning! The GND connection below line1 and line2 must be removed!. Great danger else!
But.... What is the voltage output from the transformer?
When the transformer outputs positive voltage at the lower connection, the one connected to earth, You will send negative voltage to the controller analog input, and maybe damage it.
Sorry, that was because the STC-013 has to be connected to each line in order to measure current, thats why i've put two lines there, the intention was to "illustrate" the energy that is comming outta residencial transformer, but know that in reality, the two lines are separeted and i'd never connected both, causing it to short.
Corrected, imagine that the primary of TR1 is the MV input.
I'm not sure I get it. However, drop that earth connection below line1 and line2! Keep the connection to the stc-013-1.
But.... The voltage dividing needs to be changed. What's the output of the current transformer, the stc-013-1?
Yes, thats right. The STC-013 would be coupled on one cable, having two windings, it would be connected to the voltage divider.
Please don't update the schematics in old posts. It really confuses. Post the update in the new reply. Else I can't see what changes You made. It's like starting all over again, checking new schematics.
The problem with negative voltage to the analog input is till present.
That should solve the problem, i believe. Sorry, i'll stop doing that, im new to that haha. Alright, i've changed from a 4N25 to a H11AA1, because its suitable to read both cycles of the AC.
No problem. Thanks for the schematics!
This looks a lot better!
However, 2880 Ohm for R1 looks way to low to me. Say 220 volt mains, having its peek at 380 the current would be 380/2880 = 131 mA. That will blow every opto coupler I know. 1 - 10 mA would do fine.
Wait a second! Your current transformer is now shorting the mains transformer. Some earlier version looked okey....
Maybe You should slow down a little bit.
Late here. I'm about to get horizontal...
I'll work on a better schematics, besides lowing down the R1 value, since i've changed to a H11AA1. Good night, bud.