how to monitor apparent power, real power, reactive power and power factor

[paed94]

Hye, i have to monitor voltage, current and power by using NI USB6009 board. For voltage and current monitoring part, there is no such big problems. But for apparent power, reactive power, real power and power factor part, what function should I use to monitor it? I have attached the file below. thanks

[RTSLVU]

---

@paed94 wrote:

Hye, i have to monitor voltage, current and power by using NI USB6009 board. For voltage and current monitoring part, there is no such big problems. But for apparent power, reactive power, real power and power factor part, what function should I use to monitor it? I have attached the file below. thanks

---

Short answer, you can't.

Measuring just V and I and multiplying will give you VA (apparent power), but to get Watts (true power) you need to measure the power factor. I do not believe the USB6009 can do that directly.

If you can determine the phase angle difference (lead/lag) of V and I that would give you the power factor and you could calculate the rest.

[paed94]

thanks for the reply, so i have to multiply both current and voltage signal. The output of multiply "function" should be to what "function" then?

[RTSLVU]

---

@paed94 wrote:

thanks for the reply, so i have to multiply both current and voltage signal. The output of multiply "function" should be to what "function" then?

---

I don't understand your question.

To calculate apparent power (VI) you multiply voltage (V) times current (I) using the multiply function.

What you do with the answer is up to you, but I would probably display it on the front panel and save it to a file.

[Hooovahh]

That is not the right hardware for this problem.  To read AC voltage and current at the same time, you need to have hardware that is capable of taking analog measurements at the same time.  Your hardware cannot.  If has a single analog to digital converter, and it will mux it between channels to read multiple signals.  The problem is with reading a waveform by the time you switch to read the next channel, the waveform has changed.

NI has recommended in the past a simultaneous sampleing hardware device like the cards mentioned in this white paper which can take 3 phase voltage, and 3 phase current at the same time, and in most cases without extra signal conditioning.

https://www.ni.com/en/shop/data-acquisition/how-to-measure-voltage--current--and-power.html

Some code that is useful in visualizing the phases and will perform power factor correction is the NI Electrical Power Suite toolkit.

https://www.ni.com/en-us/shop/product/labview-electrical-power-toolkit.html

There was an older version of this toolkit that was free at one point but I don't think it is anymore it is the Electronic Power Measurement.

http://sine.ni.com/nips/cds/view/p/lang/en/nid/209826 

[paed94]

hye, today i went to power lab to test my labview program with NI USB6009. After connected the  NIUSB 6009 to power supply and try to run the labview but it shows error. what is exactly the problem? i attached my labview program below

[billko]

---

@paed94 wrote:

hye, today i went to power lab to test my labview program with NI USB6009. After connected the  NIUSB 6009 to power supply and try to run the labview but it shows error. what is exactly the problem? i attached my labview program below

---

We have a better chance of knowing exactly what the problem is if you can tell us what, exactly, the error was.  😉

[paed94]

i forgot to take a picture. will let you know tomorrow, thanks

[paed94]

Hye, i'm monitoring voltage, current and power by using NIUSB6008 board, when i connected with resistive load, power factor will give me 1, but when i connected resistive and inductive in series, the power still gives me 1 instead of lagging values, how is that possible? can anyone help me. i attached herewith my programming labview

[Bob_Schor]

This is the third time you've asked basically the same question.  As near as I can tell, you have paid no attention to the advice you've been given -- the biggest change I've noticed in your VIs is that instead of a relatively small routine that tests a single input, you've added additional fancy dials and a lot more (probably unnecessary) processing without dealing with the root problem of simultaneously acquiring Current and Voltage Waveforms.

You are also apparently a slave to the Dreaded DAQ Assistant and its Evil Twin, the Dynamic Data Wire.  I recommend thinking about the Real Question(s) you want to ask, thinking about how you would ideally solve them (starting with something like "Simultaneously sample Voltage and Current Waveforms at a sampling frequency of X for a period of Y, giving me X*Y points to analyze".  As noted, your present hardware prevents Simultaneous Sampling, but you might come up with a reasonably-clever "adjustment" you could make to compensate.  Your Document (I'm serious -- write a Document that asks and answers your questions -- if you come back here, still needing help, attaching your Document showing you've given it serious thought will probably get you much more directed Help) should also describe how you would test your "fix" for adjusting the data produced by your hardware.

I strongly recommend that you use Waveforms and not Dynamic Data Wires, and learn to use DAQmx instead of the DAQ Assistant (look up the White Paper whose title starts "Learn 10 Functions in NI-DAQmx" -- a web search on this phrase will find it for you).

Bob Schor