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SNORMAN

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Reply with quote  #1 
What does this parameter apply to and what would cause it to go Up? I have read a few things but would like your answers.

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Danny Harvey

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Reply with quote  #2 
It could be bearing defects, rotor bar passing frequency, gearmesh frequencies or anything else that generates vibration in that range.

What kind of equipment and at what speed?
John from PA

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Reply with quote  #3 
Quote:
Originally Posted by SNORMAN
What does this parameter apply to and what would cause it to go Up? I have read a few things but would like your answers.


Really, answers can't be given because there is a near total absence of any data except to say the level has increased.  As Danny pointed out, we don't even know the machine!  Who set levels of "upper alert" at slightly less than 0.063 g RMS and "upper fault" at something near 0.07 g RMS.
OLi

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Reply with quote  #4 

If you have frame (like Timken I think) needle bearings in a re-winder, splicer storage part of a machine for continuous milk cardboard production like plastic application, splicing, printing cutting etc.  (possibly made in Denmark) a trend for a bearing fail looks just about like that. Trend is "normal" but the vibration where they fail are very small in comparison to the normal case. In that case it works like that, been there done that. Plant now moved to Switzerland. In this case it was a specific Tetra Pak thingy but there are other brands that may do it about the same way...... To start the tension was a bit hi, machine was not square etc. etc the trend was omitted as it was so tiny so bearings failed continuously like the machine operated but eventually it was possible to predict bearing change requirements and at a more reasonable interval. It is in this case not so hi speed but frame was flimsy and needle bearings small...... It was likely also variable speed at least at start and stop. I think the top speed were adjusted to as it was pushing the limits for the poor tiny needle bearings.
So maybe there are other similar cases that behave the same? A slightly to small or overloaded bearing application maybe? Give it some grease and see if it comes back, listen and check if it sounds like a disaster......

 


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Alex

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Reply with quote  #5 
Details please!
Jim Crowe

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Reply with quote  #6 
Could be lubrication. Looks like you are using CSI. What does the Peakvue waveform look like? If it has high amplitude and low autocorrelated waveform value with little or no periodic content it is likely lube. If you are using the 2140 with the new firmware you can take a Peakvue plus reading in analyze expert and it can help.
Shurafa2

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Reply with quote  #7 
It could indicate many things. As many members have already mentioned, I also agree that more details are needed before one can give a reliable answer.

BTW, the set points are too low compared to what I see for the machines around my small world. I never saw an alarm at anything less than 0.5 g rms.

Regards- Ali M. Al-Shurafa
SNORMAN

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Reply with quote  #8 
I am just wondering why Emerson has this parameter put in the software by default.
fburgos

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Reply with quote  #9 
Is not about the parameter been good or bad, the important thing to understand the things that happen in this region, lubrication, cavitation, rotor bar, many of the envelope technologies fall in this region.

take a look at the 1k-20khz trend vs peakvue

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SNORMAN

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Reply with quote  #10 
the important thing to understand the things that happen in this region, lubrication, cavitation, rotor bar, many of the envelope technologies fall in this region.






This is what i was wondering.
OLi

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Reply with quote  #11 
Around 1kHz you have a mechanical resonance in the outer ring of most bearings pretty regardless of size, believe it or not I hardly did until I saw it, even more unbelievable are that it can be excited even inside a bearing mount at full load and operation but it does. If you then have a bearing damage, friction from bad lube etc. etc. energy, signal levels are increased around that resonance and are easily detected with that type of parameter you have and it get quite sensitive. So a variation of that, including a similar version are things I always use as they trend nicely and are sensitive and give the warning in time that I like to have. Then you need to look at what the source of the signal is but that is more standard analysis. So that is why I would say CSI had this from the very start, it is effective and simple. However it does detect the coupling guard touching the coupling etc. also...... metal-metal contact of most kinds, even touching in turbine bearings.....
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Ralph Stewart

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Reply with quote  #12 
Quote:
I am just wondering why Emerson has this parameter put in the software by default.


To me, a simple exclamation as to "WHY EMERSON" uses this as a default would be to alert the analyst to the fact that something is happening within this frequency range and the burden falls upon the analyst or data collection person to collect more data, preferably, at several different Fmax(s) or bandwidths, to determine where, in this frequency range of 1K to 20K Hz, the cause(s) is (are) located and what they relate to that will increase the trend value.

Quote:
the important thing to understand the things that happen in this region, lubrication, cavitation, rotor bar, many of the envelope technologies fall in this region.


This quote is a must to know after one determines the location of the increase and knows what might or could happen at that location.

Just my opinion and I could be totally wrong.

Thanks and Have a Great Day,
Ralph

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