measuring harmonic current

[loubop]

hi all

i'm currently working on my honours project and uni, and im starting to go round in circles, was hoping i could get pointed in the right direction.

i want to measure the harmonic currents and sub harmonic currents of an induction motor, using labview, via a DAQ.  i can get the input current in numerical and graphical form, but im having problems with the distortion measurement block.  i can get the THD as a numeric output, but not graphical, the same for when i set the block to output a specific harmonic.  is it just not possible??? do i just have to go with the numbers??

i also used the harmonic analyser block, but it doesn't appear to be doing much at all!!!

my other ideas involve the spectral measurement block or using an fft block, from which i was gettting numerical outputs once again, but no graph. 

if anyone has any suggestions as to what i should maybe look into it would be much appreciated!!!

thank you, louise

[Rich_Silley_NIUK]

Hi Louise

If you are using the Distortion Measurements Express VI you should be able to display the THD output on a graph by right click on the THD output and selecting "Create >> Graph Indicator". Would you be able to post an example VI showing your attempts so far? This will help me direct the advise I give you based on how you are trying to use the various functions.

Regards

Rich

NI|UK

[loubop]

ive attached my project for you too lok at.  it's not that i dont have a graph, i just that its not showing anything!!! i can get a dot when i go in and change the settings,  but i would prefer a line.  this may not be possible however.

thnk you , louise