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Basil Shaji

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Hi,
I am using CSI 2130 for vibration data collection and i check the spectrum from field itself to identify the peaks and corresponding frequency. The device have an option called List Peaks wherein it displays all peak frequencies and its magnitude. But the listed peaks always have a low magnitude and different frequency than the one visible in actual spectrum. Could anyone explain this ?
Danny Harvey

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Reply with quote  #2 
It lists every identifiable peak in the spectrum and lists the amplitude at that peak.

My 2130's are in storage so I'm not sure but you may be able to use a harmonic cursor to highlight a set of harmonics and then ask it to identify just those peaks.

Regardless, in the table that List Peaks displays, set of harmonics will stand out from the rest in orders of magnitude.  It's not perfect but you can manipulate the cursors on the spectral display will quickly identify sets of harmonics.
Basil Shaji

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Quote:
Originally Posted by Danny Harvey
It lists every identifiable peak in the spectrum and lists the amplitude at that peak.

My 2130's are in storage so I'm not sure but you may be able to use a harmonic cursor to highlight a set of harmonics and then ask it to identify just those peaks.

Regardless, in the table that List Peaks displays, set of harmonics will stand out from the rest in orders of magnitude.  It's not perfect but you can manipulate the cursors on the spectral display will quickly identify sets of harmonics.


Thanks for the input !
Curran919

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Quote:
Originally Posted by Danny Harvey
It lists every identifiable peak in the spectrum and lists the amplitude at that peak.


Does it identify peaks (values that are larger than both neighbouring values), or does it just give the highest values? In other words, if you have a single dominant peak spread between two bins, will it report them separately? Report the higher of the two? Sum them somehow?
Danny Harvey

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Curran,

I don't recall. I suspect that it reports the value of every bin. I think I quit using the feature when they came out with a cursor that would jump between sets of harmonics.
John from PA

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I'm not familiar with the 2130, but many devices with a "list peaks" capability also have a threshold setting.  In other words list all peaks above 2 mil pp (50 µm).
Basil Shaji

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Quote:
Originally Posted by Curran919


Does it identify peaks (values that are larger than both neighbouring values), or does it just give the highest values? In other words, if you have a single dominant peak spread between two bins, will it report them separately? Report the higher of the two? Sum them somehow?


Hi,
Say you have a peak like the one in the attachment in your spectrum (FFT), then the list peak feature will extrapolate and display the peak values as point 3. But the cursor will still be at point 1.
I think it identifies all the peaks.

Thanks

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jpeg IMG_20200506_183929562.jpg (166.32 KB, 10 views)

RustyCas

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Reply with quote  #8 
Basil, if you are looking at the peak list ON the 2130, there are probably more peaks than will fit on the screen. you should be able to scroll down using the arrow keys.  If you are looking using Orders, the 1X it uses to calculate orders is the RPM for that point you have set up in the database.  Orders will not be accurate unless you are actually inputting the RPM in the field before you collect the data point.
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"The trend is your friend"
Basil Shaji

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Quote:
Originally Posted by RustyCas
Basil, if you are looking at the peak list ON the 2130, there are probably more peaks than will fit on the screen. you should be able to scroll down using the arrow keys.  If you are looking using Orders, the 1X it uses to calculate orders is the RPM for that point you have set up in the database.  Orders will not be accurate unless you are actually inputting the RPM in the field before you collect the data point.


Rusty,
Understood.
In Plot Data option we can locate peaks by moving the cursor. But, i couldn’t match the located peak frequency(just by moving cursor, not with locate peak option) with the frequencies provided by List Peak option.
Later i figured out why the mismatch was happening(previous reply).

Thanks

John from PA

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Reply with quote  #10 
2130 manual is at https://www.maintenance.org/fileSendAction/fcType/0/fcOid/400998571506985888/filePointer/401420994973995345/fodoid/401420994973995341/2130_ru_refmanual.pdf.  I'm not sure if its presence violates any CC laws.
electricpete

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Reply with quote  #11 
Basil, thanks for sharing your resolution of the question. 
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