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SNORMAN

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Reply with quote  #1 
This compresor makes my analyzer do this. This is the only place where this happens what could be causing this. I have other identical compressors that do not make this screen pop up. I have had the same results with different cables/accels/and analyzers. If i keep pressing enter it will eventually take the reading.?????

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fburgos

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Reply with quote  #2 
I had this on one screw pump, 50mm/s rms added an old credit card between sensor and machine made the trick to measure the machine and send it to repair based on overall vibration
SNORMAN

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Quote:
Originally Posted by fburgos
I had this on one screw pump, 50mm/s rms added an old credit card between sensor and machine made the trick to measure the machine and send it to repair based on overall vibration

so Is it do to extreme amplitudes?
RustyCas

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Reply with quote  #4 
Yes, probably “saturating” your accelerometer. If you want to accurately measure the vibration, you probably need something like the 10 mv/g accel below. Or as Ferdy, suggests, use something to semi-isolate your existing accel (but only as a reality check).

https://buy.wilcoxon.com/793-10.html

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Walt Strong

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Reply with quote  #5 
The screen shows analyzer cannot detect Bias Voltage, so how can this be caused by vibration overload?

Are you using an input adapter with both Voltage and Accelerometer ((ICP voltage) connections? If yes, then check cable connection or switch setting. If the vibrations are actually too high for accelerometer, then you should be able to "feel it" and see that waveform show peaks in excess of accelerometer rating. You could also try to measure vibration on same machine at a location where they are (or should be) lower for a "sanity check".

Walt
RustyCas

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Reply with quote  #6 
Walt, I’ve seen this when accel is saturated.
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fburgos

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Reply with quote  #7 

Quote:
Originally Posted by SNORMAN

so Is it do to extreme amplitudes?


Quote:
Originally Posted by Walt Strong
The screen shows analyzer cannot detect Bias Voltage, so how can this be caused by vibration overload?

Are you using an input adapter with both Voltage and Accelerometer ((ICP voltage) connections? If yes, then check cable connection or switch setting. If the vibrations are actually too high for accelerometer, then you should be able to "feel it" and see that waveform show peaks in excess of accelerometer rating. You could also try to measure vibration on same machine at a location where they are (or should be) lower for a "sanity check".

Walt


I ve seen this screen only twice.

One was obvious a cable problem, skyslope moving around on any point etc, keeping cable strainght worked fine, etc (check verify hardware, home, f7, alt, f11 and move your cable if bias jump change cable/accelerometer)


Next time it happened only on one or two points on this machine, same measurement on the next machine/direction worked fine hardware check was fine, all measurements had a lot going on at high frequency... could this be a mouting issue added the card... it measure fine then who knows why it worked but it did
OLi

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Reply with quote  #8 
If your machine have a frequency that match, "excite" the IRL mounted resonance in the accel it may saturate easier. Changing mount by adding materials btw. sensor and machine change mount or mechanically filter the signal. We have a frequent customer that buy a mount stud with that effect as they add sensors on identical machines and I see no other reason for doing that.
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fburgos

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Reply with quote  #9 
heres a short video.

 
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mp4 20190809_102659.mp4 (18.70 MB, 32 views)

Walt Strong

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Reply with quote  #10 
Fergy, That was a really nice video that clearly demonstrated your previous comments. 

I had one instance where sensor overload was indicated (CSI 2120-2). I gripped the accelerometer and cable boot tightly while making sure the accelerometer base magnet had good (no rocking) contact, and could then make a measurement.

I had another instance on a gearbox with bearing fault (EDM) that was producing vibration levels so high that the flat rare earth magnet was sliding down a vertical surface. The 80+ g-level was exceeding the accelerometer 60-g rating, but the analyzer was still taking a measurement. 

Walt
Sinski

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Reply with quote  #11 
I have had this happen in the past as well and what Fergy does with the card has worked as well. On different types of machinery as well. I had one the other day where the drive end bearing of the pump had a severe inner race fault and the analyser would alternate between me being able to take data or taking crap data. I just moved the accelerometer a little away from the bearing housing but still on the pump housing to get good quality data. 
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