VFD bearing failure
VFD bearing failure
(OP)
Is anyone experiencing bearing failure in VFD motors? If so, what have you done to solve the problem? Is it worse with some VFDs than with others? What are your motor sizes? How long are your motor leads? Any other useful thoughts would be appreciated.
Lewis
Lewis





RE: VFD bearing failure
to over come the problem:- the bearing that is faulty has to be replaced with either an insulated bearing or insulated housing. a carbon brush is then fitted to the housing of the good bearing and runs on the shaft, this completes the earth path.
should you require further assistance or information please advise "e"mail or fax no.
kind regds.
RE: VFD bearing failure
Inserting filters into the output of the VFD reduces the dv/dt and therby reduced the bearing current problem. It also reduces EMI problems but it costs money.
You may be able to add dv/dt filters externally to reduce this problem.
Mark Empson
http://www.lmphotonics.com
RE: VFD bearing failure
Where this problem is most commonly observed is in clean room applications. In clean rooms the drive carrier frequency is usally turned to a maximum (16-20kHz) to try and move motor noise to an above audible range. This causes the damage occurs faster. The damage is also more easily noticed in the clean room enviroment since the bearing damage first manifest itself as noise in a quiet enviroment.
If you have already have the drive and motor see how low the carrrier freq can be set and turn it down to that level. (typically around 1 to .5 kHz)
MarkE-
When I was working for a drive manufacture several years ago they were experimenting with using a conductive grease for the bearings as a solution to this problem. I don't follow drives very closely anymore,, do you know if conductive grease is a practicle solution.
RE: VFD bearing failure
http://www.ab.com/drives/techpapers/ieee/IAS96%20bearing.pdf
The company is Shaft Grounding Systems the number is 541 997 4068
RE: VFD bearing failure
Thanks.
Lewis
RE: VFD bearing failure
The Big I (Intel ) uses them on all there VFD motor applications. The company is Shaft Grounding Systems, When I called this am they said their web site was broke and it sounds like they don't know how to fix it. If you call them they will fax you lots of stuff but other wise there back in the stone age. The papers they have are very good.
The guys who invented the system came to an IEEE IAS meeting here and gave a very good presentation. They know the problem and what to fix it with.
RE: VFD bearing failure
RE: VFD bearing failure
RE: VFD bearing failure
Some previous postings are availablve in this forum including the complete list of AB papers written on this topic.
http://www.ab.com/drives/techpapers/ieee/ieee.html
RE: VFD bearing failure
is to carry a unique ground wire to
each motor that is bundled with the
phase wires for that particular motor.
The idea is to keep the loop area between
the phase wires and the ground wire small.
This minimises the inductance of the return
path for common mode currents.
Carry this ground wire into the panel
and land it on the ground terminal of
the drive that is associated with it.