×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Bearings of motors powered through VFD

Bearings of motors powered through VFD

Bearings of motors powered through VFD

(OP)
On site we have 3 400V motors 200kW , spupplied via ABB ACS 800 inverters. he motor bearings are nit special insulated bearings , for applications that use inverters, they are typical nearings. The frame of the motor and the driven fan are grounded, the motor cbles are special shielded power cables. Is it possible for us to change the bearings with other tyoes, special insualted?

RE: Bearings of motors powered through VFD

Hello,

not quite sure what you ask.

Do you have standard (not insulated) bearings and want to put in insulated (Insocoat) bearings?

That would usually not be a problem (except that Insocoat may run a little hotter if coating is on outer rim).

Why do you want to change bearing types?

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Bearings of motors powered through VFD

I've had problems with this in the past myself and we corected the problem by installing a grounding device on the shaft of the motor.  Your problem is shaft currents...

RE: Bearings of motors powered through VFD

depending on the length of the run you may have a commom mode voltage problem. this may be resolved by putting a common mode filter on the leads from the inverter to the motor.

RE: Bearings of motors powered through VFD

npower0073
Do you have a problem with your bearings or do you think you might have a problem with your bearings?
If you have a problem then first be sure it is related to the inverter before going further otherwise its an expensive process and you may be back to square one. The type of bearing failure is quite specific if it is.

RE: Bearings of motors powered through VFD

Hello npower0073,

If the motors are running fine then you don´t have nothing to alarm. But I think the best you can before take some action about the bearings is to do  a question for your motor´s dealer or to the manufacturer about the motor´s design.

Normally you could find two typical designs for inverter´s motors, one with insulated or hibrids bearings and other with standard bearings and OD shaft insulated, I think the last could be your case.

Regards

Carlos

RE: Bearings of motors powered through VFD

you can find out for sure if your problem is shaft currents by replacing the bearings and cutting the old bearings in half to examine the internal surfaces--if you see an 'etched look' that is a sure sign of shaft currents. good luck..

RE: Bearings of motors powered through VFD

ravensfan
that's quite a major undertaking on 3 x 200kW just to see if there is a problem!
 
There is a device coming onto or already on the market called BEPPE Bearing predictor developed by one of Eng-Tips regular tipsters Skogsgurra. Try http://www.gke.org/beppe/files/Bearing%20currents%20on%20one%20page%201.pdf
At the moment there is nothing really on the market to predict if EDM is causing premature bearing failure other than setting up an oscilliscope and knowing what to look for.
BTW, I have no commercial interest in BEPPE. I wish I did as it is a great little device!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources