06-06-2016 10:57 PM
Solved! Go to Solution.
06-07-2016 07:30 AM
Since noone else is answering, I will give you an advice.
Not sure if it is only me, but I guess the others do not really understand what you want, too. But I will give it a try.
So, you have a myRIO and you are measuring 6 analog voltage signals (3 of them can be used to calculate the current, using a given resistor value).
The "current sensor" has an output range from 1.5V to 3.5V? The other "voltage sensor" has an output range from 1V to 4V?
Using U=R*I and P=U*I will give you the power. But I guess you already know this and you want to know how to get the measured voltage values.
The fastest way is the following.
1, Create a new project in LabVIEW (use the myRIO template, the myRIO has to be connected to the PC via USB)
2, Add a new target (which is the myRIO) (I am not sure, but I guess if you use the myRIO template, the myRIO is added as a target automatically)
3, Right click on the target --> New --> VI
4, If you have done all correctly, you can choose "myRIO" in the function palette
For a first try, you can use the express VIs to read the voltage of several ports, there are several examples given by LabVIEW. You can find them if you click on the "help" tab on the frontpanel / blockdiagram ---> Find examples... A new window opens, here you can search for myRIO examples.
hope this helps a bit
kind regards
slev1n
06-07-2016 08:02 AM
06-07-2016 09:02 AM
So you need help to read the voltage values with your myRIO.
Since I have no knowledge about your electrical power suite library, I can only recommend you, to follow my instruction. Create a new project with myRIO template (I think if you connect your myRIO with your PC a window pops up, giving you the option to create a new myRIO project). Than you can use the myRIO library which you can find in the function palette. Using the express VIs at the beginning is very easy, later you can use the normal VIs to read all the analoge voltages from different analog ports.
Hope this helps
kind regards
Slev1n
06-07-2016 10:45 AM
06-07-2016 11:05 AM
06-08-2016 02:00 AM
Well, according to your picture, you already managed to read in the analog voltage values. The first step is done.
I have to confess, that I am not that familiar with the 3 phase system. But after some "google" I have found the following formula:
P1= Sqrt(3) * U1 * I1 * cos(phi); cos(phi) = power factor (some examples for power factos are here: Power factors)
P total = P1+P2+P3
I am a bit confused with cos(phi), not sure if its just a power factor, or if it is the phase of the sinusoidal voltage of one strand of the three phase system.
Maybe someone being more familiar with that can help from here?
kind regards
Slev1n
06-08-2016 08:15 AM
06-08-2016 09:11 AM - edited 06-08-2016 09:14 AM
there is the electrical power suite available for download that could help you
http://www.ni.com/white-paper/8652/en/#toc3
without using it, to calculate the power factor i would do:
1. take the Voltage signal and the Current
2. do an FFT over each
3. limit results samples to an observation period (not larger than the waveform)
4. convert in complex arrays
5. take Real part to find peak indexes
6. use index to catch the phase value -> then difference-> then cosine
as in the attached picture.
hope this helps
m.
06-08-2016 10:17 AM
I am very grateful for your help, this example helped me a lot.
Please Could you send me an example with three voltage signals and three current signals? My circuit is three-phase
Best regards
David