CVHF650 bearing problems any help?

[brian woodard]

We have two Trane CVHF 650 ton units with Adaptive Frequency drive.Both units have lost bearings .Trane has installed ceramic bearings and a brush to take eddy current to ground.Does any one know of a fix for this problem.

[chillermun]

I am sorry to say but the ceramic bearings are Trane's Fix. I just went through the same problem with two new machines last summer. In fact we lost two sets of bearings before Lacrosse sent us the Ceramic bearings. This was before the service bulletin about the ceramic bearings came out. We were one of the Test Cases.

[chillrdude]

Originally posted by brian woodard
.Trane has installed ceramic bearings and a brush to take eddy current to ground.Does any one know of a fix for this problem.

Supposedly that is the fix, time will tell.

[chiller mekanik]

Can we talk about these bearings a little more?
What is the service bulletin # & does anyone know how applicable it is to other Trane machines?
For example: I'm getting ready to install a VFD on a CVHB1550, can I expect any problems related to this discussion?
Similar, completely different or should I start another thread?
Thanks...

[snipe70e]

We have 3 machines, 1 600 ton, and 2 1000 ton. Buildings been open less than a year. Had to replace bearings in the 600 ton unit. Trane also changed bearings on other two units all under warrenty.

[chillermun]

The AFD on the chiller induces a voltage on the shaft causing the ball bearings to discharge to the bearing race then to ground. The arching of the discharge damages the race and you now no longer have a quiet centrifugal you have a centrifugal that sounds like a screw and progressively gets LOUDER. The first fix was to install a grounding kit to the shaft. Then when this didn't work, the bearing with ceramic balls came out along with a new shaft grounding kit. The bulletin # is CTV-SVC-15B-EN. Don't know if They (Trane) Have Ceramic bearings for the CVHB motors but I would ask about them if it were me. Sure would suck to have to go in and change the bearings a month later. Good luck and keep us posted. If I can help with info let me know.

[RichardL]

This problem is surely not going away anytime soon....
The "Grounding Brush" was tried in a lab recently by Reliance, along with ceramic bearings, bearings nested in an insulator ect...Bearing failures occurred rapidly (In hours in one case)..
It appears that the capacitively coupled elements involved hae three(3) seperate directions of current flow not just the one the "Grounding-Brush" is intended to eliminate...
The brush compounds the the problem with the two remaining sources of shaft currents and actually quickens bearing failure.....
All this information is available on-line using our beloved Google and punching in "Shaft Currents" & the like....
I have spent hours reading the works of those far more informed than I...and can assure one & all that in short....
There ain't no quick & easy cure for this problem....
Ain't it a *****...The better the workings of the AFD,VSD whatever you wish to call it...The faster the motor bearings fail as a direct result of faster & faster switching times of said VSD....(Some are upwards of 25khz)
Trust me....The motor manufacturers are working overtime to find a remedy....but the more they learn....the bigger the problem becomes....
Do not believe me or anyone else you talk to....Do some damn research yourself & quit hollering help me...help me...Like a wounded duck trying to save it's little ones..
Perhaps we should have listened to Ol' Alva Edison when he insisted on using DC as the power to be distributed....
Too bad he lost the court case to Charles Westinghouse & Mr. Tesla....
Too bad indeed.

[Edited by RichardL on 01-04-2006 at 06:53 PM]

[kwillmech]

Problem can be expected on LF 1.5 and 2.0 drive equipped chillers, factory installed or aftermarket.

Ceramic bearings are the current fix.

[skyhawk]

Not so much the LF 1.5 as with the 2.0.

The LF 2.0 with it's active front end and higher speed switching is worse.

[pacsbhicks]

Trane CVHB chillers have sleeve bearings on both sides not ball bearings. The vfd will not affect those. York has been putting vfd's on their chillers for 20 plus years will ball bearing and no failure like Trane. I have been told that they use snubbers on the DC sign wave to clean it up not to send voltage spikes to the motor.