I remember some years ago when MARS

[ScusaMe]

I remember some years ago when MARS Candy in Chicago area had an epidemic of Baldor motors that had a high incidence of bearing failure. They put vibration monitors on motors newly installed and could watch the vibration level increase over a short time of operation.

Seems the problem was that the Baldor motors were operating in ..... S A T U R A T I O N ..... which caused the problem.

If ya can, I'd try a motor from a different manufacturer.

 

[electricpete]

Thanks for the heads up. Baldor does offers a line including the former Reliance line of severe duty motors, "841XL" series (meets IEEE841). You pay a little more, but I tend to think they are built well and we have had good experience with those.

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(2B)+(2B)' ?

 

[ScusaMe]

Pete,

Baldor is a much different company today than it was some 10+ years ago.

With their purchase of the power transmission and motor product businesses of Reliance / Dodge from Rockwell (Rockwell kept the drives business and today announced the purchase of a Chinese medium voltage drive manufacturer)... and their subsequent purchase by ABB, they truly are no longer the same company. But back then, they were in a locked competitive struggle with Leeson Electric Motors (aka Regal-Beloit - aka Regal) to make the most inexpensive motor possible.

The point to be made here, Pete, is that operating a motor in SATURATION can cause premature bearing failure ... and to look for other causes than just mechanical.

Kind regards,

 

[electricpete]

Thanks for clarifying.

I gather these bearings also had high temperatures (observable on housings) and this led to the bearing failures?

The design/quality concerns you're citing relate primarily to older Baldor motors (10 years), correct?


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(2B)+(2B)' ?

 

[ScusaMe]

Pete,

This event goes back to sometime in the 90's.

Details are a bit sketchy.

I do recall that I was at a seminar presented by Baldor and sat next to a PhD. (who's name escapes me) who was responsible for plant engineering of all M&M Mars Candy. Sitting across the table was the speaker from Baldor. About mid-way thru lunch the gentleman from Mars brought up the subject of the multitude of bearing failures they had and were experiencing with Baldor's Premium Efficient motors. We learned that the previous generation of Baldor motors did not have this problem .... and as they eventually ran their inventory down and re-ordered, could no longer obtain the older motor designs as everything had to be Premium Efficient as dictated by D.O.E.

I know they got TVA involved in doing a study ..... I also don't think it was a temperature issue as they did not see a rise in temperature until the bearings were observed to be in failure mode.

I do know that the rep. from Baldor had no answer ... and tried to tap-dance away from it. The gentleman from Mars Candy though was very upset as it was costing the company a lot of money; not only in lost production but in having to trouble shoot and investigate the problem and purchase replacements.

About a week later, I happened to be at another motor manufacturer's facility and one of their engineers held a high position within the NEMA MG-1 committee. I mentioned the Mars Candy problem, and he immediately stated that the cause was due to the motors operating in saturation, which, he said, was how the Baldor motors were able to meet the new Premium Efficiency numbers without having to invest a lot of money in R & D ...

That's it, Pete .... reached the end of the memory bank.....

Cheers.

 

[electricpete]

According to Austin Bonnett's "UPDATE ON AC INDUCTION MOTOR EFFICIENCY" from IEEE PCIC-93-25), high effiency motors due tend to have higher airgap flux density to reduce full-load rotor I^2*R loss, at the expense of lesser increase in core losses.

I'd have thought temperature would be a logical factor in the bearing failure scenario. And we certainly see high efficient motors run hotter due to reduced energy devoted to cooling.

If not temperature, I wonder what's left... bearing currents? I haven't heard of that on small motors. There may certainly be something I'm overlooking.

Anyway, thanks for sharing.

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(2B)+(2B)' ?

 

[electricpete]

My statement about bearing currents, I assumed not vfd, but we know about assumptions...

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(2B)+(2B)' ?

 

[ScusaMe]

My recollection is that they were DOL... conveyors and such ....

 

[MiketheEngineer]

I always thought chocolate was good for you??!!

 

[ScusaMe]

Mike,

'tis a subject for tasteful discussion, perhaps in another venue .....

Three Muskateers anyone ?

No SNICKERing now.