topic Re: Need help here!!!!!! in LabVIEW

Need help here!!!!!!

K Tan — Fri, 03 Nov 2006 05:02:23 GMT

Anyone done power quality analysis before? Pls share your idea with me and some .vi. I am a newbie.

What's the difference between THD found in (analyze->waveform measurment) andin(signal processing->frequency domain)

I tried 2 of them but the calculated result for THD are not the same.Which one is the correct answer? Or both also wrong?

My fo=50hz,

formula=a*sin(w*t),

#s= 21

higest harmonic=3

Why the harmonic frequency are not the same?

How to sketch out the harmonic analysis of a distorted current waveform?

Pls help.....

Thx

Re: Need help here!!!!!!

DuffmanSays — Mon, 06 Nov 2006 16:40:22 GMT

K Tan,

After taking a look at your code, it appears that you are using the Harmonic Distortion Analyzer VI correctly, but not the Harmonic Analyzer VI. If you take a look at the detailed help for the Harmonic Analyzer, you must specify the window used for the Scaled Time Domain Waveform VI.

If you take a look at the help for the Harmonic Analyzer VI, you will see the details of how to correctly use this VI to make a THD measurement. I hope this is useful for you. Please post back if you are still having trouble. Thanks,

Mike