How many of you have, or have seen this in motors, and how if any did it affect your motor life?

I'm familiar with this somewhat, but have not seen this here much.

The past few months I've noticed this humming, and it cycles from loud to almost silent, every 3-5 seconds.

Looks like a bit of modulation going on here in the timewave. Can you shed some light on this for me. I noticed my bearing ACC starting to trend upwards as well...

Thanks,

If beating occurs with a 3-5 sec period you have to set up the instrument to acquire data for at least 10-15 sec to see it in TWF. The TWF above is not capturing that. it does show either modulation or beating at some other frequencies though. To conclude reliably what is going on a spectrum is required.

David

May be 2XLF is close to 2XRPM. This will produce beats .Even 1XLF may be beating in presence of 1XRPM. This beating phenomenon is very common and not dangerous.

As stated it could be 2LF beating with 2x on 2-pole or 4x on 4-pole.

Could also be pole pass sidebands around 1x.

As David stated, good to investigate with high resolution spectra.

If pole pass sidebands are present around 1x in vibration, it's a good idea to check for pole pass sidebands around 1*LF in current.

Not really seeing the Fp or Fs at 1X, nor 2Fl. I won't too much worry about this one yet, but will continue to monitor closely.Got a real eratic spectrum 4X and 5X peaks in the 1HGE3 2HG3E. I'm looking at another strange problem on those hot fans I spoke of about a week ago. Will post again shortly.

Thanks Guys,

Check the feet bolts, it could be loose.

You may have a trouble in the magnetic core laminations....just thinking

Rod,

From the TWF it looks like you have modulation of RBPF by 1xLF ( 60 HZ). From math point of view it could also be 2xRPM, if 4 a pole motor, but 2xRPM makes no sense from physics prospective.

I observed similar effect, what is possible 1xLF, in my post
http://maintenanceforums.com/e...61085912/m/288105863

I suggest taking also demodulated data.

Again this has nothing to do with the beating. To detect beating at 4 sec interval high res data is needed.

Sorry for not replying in a more timely manner. I've been on turnaround for about as month now. I'll get back to the post next week and check out all your info.