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Ralph Stewart

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Reply with quote  #16 
I think you are correct Walt. [smile]

Vibe-Rater,

What is the order of 6xLF in any given spectrum? Is it a known order before hand?
It is not a multiply of 1x? I think not.

So one would have to calculate what the frequency peak is in cpm or Hz, wouldn't one?

I believe one should use what one is comfortable with. right?

Just asking?[smile]

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Ralph Stewart
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JuddJones

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Reply with quote  #17 
Why not understand and be proficient in all 3?
Ralph Stewart

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Reply with quote  #18 
Thanks Big J.

Quote:" Why not understand and be proficient in all 3?"

Very good question.

I agree. BTW, I am, just in case anyone might think otherwise. [smile]





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Ralph Stewart
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Reply with quote  #19 
All things are either synchronous or non synchronous to shaft speed (and fixed multiple thereof) whether that be 60Hz or most part of the rest of world 50 Hz. So it all relates to 1x. Except of course the very few fixed frequency examples - one of which you point out. Electrical. But we can deal with those exceptions.  And then we go variable speed. At least not without a good old calculator and a lot of time.
Vibe-Rater

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Reply with quote  #20 
But you are correct, you'all must do what we are comfortable with.

Sinski

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Reply with quote  #21 
Quote:
Originally Posted by Ralph Stewart
Weller,

Question on the spectrum.

Why is the low end of the frequency showing 0 to 360 Hz so close together and the harmonic of 360 is much farther away from the fundamental frequency of 360?

Even though the "0" is showing on the low end of the scale, is the data actually starting at about 180 Hz or so? This makes the fundamental of the 360 seem out of proportion to the 1st harmonic?

Just asking. [smile] It sort of made me do a "double take" at my first glance of the spectrum.

Also see my question on the closely spaced sidebands in the picure.

Thanks and Have a Great Day,
Ralph

sb3.JPG


Ralph

Going by the picture he weller initially shared suggested to me he meant those sidebands were running speed (6.4Hz, 368cpm). No on that picture he had a what looked like a sideband cursor which marked the higher sidebands so i assume those to be 6.4Hz. If you look close enough it looks like there are sidebands at half that within that circle you mark so therefore assume those to be 3.2Hz (0.5x orders if running speed is 6.4Hz). I have not come across alot of electrical faults on DC motors before but could this be some sort of eccentricity or even a rotor rub etc.
Would be handy to have a zoom of that area and the sidebands marked with frequencies so we not what we are looking at. 
Ralph Stewart

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Reply with quote  #22 
Sinski,

Thanks. I see I misread weller's reply to my previous question. [rolleyes]

Sorry welller. [smile]

Thanks and Have a Great Day,
Ralph

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weller

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Reply with quote  #23 
FYI - Update. Drive was tuned by drive vendor.Maintenance reports no problems. Have not returned to machine yet to gather data, possibly in the near future.
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