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Noknroll

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Reply with quote  #1 
I don't usually pay attention to 100Hz
But this one got my attention, Over head motor measured via extension pole and I could feel it growling through the pole.
Any thoughts on why it would be so severe?

3m108 vel.png  3m108pkv.png

OLi

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Reply with quote  #2 
1 phase connection in the cabling bad? Normal in "older" plants. 1 phase in the breaker bad, just as common. It may even eventually be the motor......
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Şahin GÜLLER

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[QUOTE = OLi] Kablolamada 1 fazlı bağlantı kötü mü? "Eski" bitkilerde normaldir. Kesicide 1 faz kötü, aynı yaygın. Sonunda motor bile olabilir ...... [/ QUOTE]
Şahin GÜLLER

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Reply with quote  #4 
You must check electrical arc jump bearings
MachDiag

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Reply with quote  #5 

Possibly a stator or phasing issue? 

---------------------------------------------------------------

What are the amplitudes in each measurement location (vertical, horizontal, axial)? 

If you zoom in around 2xLF, are there measurement locations that have sideband peaks?

electricpete

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I would suggest check the current balance. That's usually a quick easy non-intrusive check... once you get past electrical safety requirements. 

Noknroll

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I informed my site host before leaving, he took a note so hopefully he will get electrical checks done
Şahin GÜLLER

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[TEKLİF = Şahin GÜLLER]
Elektrik ark atlama yataklarını kontrol etmelisiniz
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Şahin GÜLLER

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Reply with quote  #9 
amplitudes vary according to engine speed
Danny Harvey

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Reply with quote  #10 
I don't normally give 2 x lf much thought either but that looks like a big problem to me.

I would have done the same.  Report it immediately as a likely emergent problem and hope that they let you know what the electricians find.
Noknroll

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Reply with quote  #11 
This from the Engineer.
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We had a look at the motor there were no issues with the circuit breaker or phase loading, terminals were also tightened up.


above is extracted from an email telling me another motor nearby seized a week after last survey, Cause unknown at this stage.......I wonder if there plant Id's are mixed up????
Danny Harvey

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I have one client with no nametags on any equipment. I used that very scenario to scare them into tagging the equipment.

Problem is that they made ME do it.

I should be more careful what I ask for. 

But going from almost nothing to 15 mm/s is nothing to ignore.  When will you collect data again? 
Noknroll

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I'll be back to collect data 3rd week in the month. Will be interesting to see what I find
electricpete

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Reply with quote  #14 

Quote:
We had a look at the motor there were no issues with the circuit breaker or phase loading, terminals were also tightened up.

That’s confusing to me because it doesn’t tell me if they checked found a current unbalance or not. My thought process is the checking current balance is the very first thing you check in a systematic approach because it’s usually easiest.  And if you find a problem with severe current imbalance that’s good data indicating something needs to be fixed, BUT there is still some work to narrow it down.    It could also be:

-      Voltage unbalance further upstream, maybe due to unbalanced single-phase loads in the facility, or problem with utility supply.

-      Motor electrical problem like shorted turns or part of a winding open.  It isn't common for a motor to continue running without a trip after this kind of fault, but it does happen, especially for random wound motors. 

There are a variety of troubleshooting methods.   One way to distinguish between the motor and supply is to rotate the leads at the motor and see if the lowest-current follows the motor lead (motor problem) or stays with the power supply phase (power supply problem). There are also a variety of voltage measurements that can help narrow things down.  


Noknroll

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Reply with quote  #15 
Thanks for your input Pete, unfortunately I'm not electrically trained or competent in the dark art of elctrickery to put forward your suggestions, so have to accept that what the electricians at the facility have done is enough to uncover any issue. I'm quietly confident the motor that they told me seized is the big 100Hz motor.....
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