SCIM motor brand issues 3

[jraef]

I am involved in a project where the user is buying a Weg SCIM motor that I will need to drive continuously into the service factor by about 6%. In the past I had a spate of very bad experiences that lead me to state that I would never buy another Weg motor again in my career. Although I am not technically buying this one, I have influence over the owner because I am making the system work. When I protested the Weg motor selection, I was repeatedly asked if I had tried Weg lately because they fixed some systemic problems a few years ago. To be honest I admitted no, I had not tried them in over 9 years so it is theoretically improper for me to reject them out-of-hand. My question for this group is;

Has anyone had recent experiences with large frame (447T and up) Weg motors in the past 5 years that would make me change my mind or stick to my guns?

"Venditori de oleum-vipera non vigere excordis populi"

 

[edison123]

jraef,

Right now, I have in my repair shop, a WEG (Brazil), 6.6 KV, 225 KW, 2 Pole, IL/IN frame 8.5 Model HGF 315 motor for rewind of the VPI stator (interturn failure + earth fault). This new motor, driving a reverse osmosis pump for a 250 MW power station, has failed within 10 months of commissioning.

My impression is that while workmanship and materials used is pretty good, the VPI process - which always gives me willies - was not up to the mark. Poor impregnation of turns has lead to turn failure and later to earth fault.

 

[uno]

We have been using WEG motors for some of our projects and haven't recieved any failure reports as yet. To avoid failures in high voltage motors it is prudent to have stringent testing criteria in your specification/contract for instance to have turn to turn insulation testing on stator coils as per IEEE Std 522 or to install surge arrestors or perform vibration tests.Of course it might increase the cost of motors.

 

[jbartos]

Suggestion: Visit

http://search.netscape.com/ns/boomf...+%2B+%22motor%22&clickedItemURN=http%3A%2F%2F

http://www.weg.co.nz%2Fscale_motor....ove_url=http://www.weg.co.nz/scale_motor.html

then click on WEG Brazil and possibly English
for References

 

[DougMSOE]

I had to deal with these motors in the last 5 years and I will never buy one of these again.
However, the VPI process is VERY CRITICAL, and unless this is performed correctly, nothing will last very long.
With that said, when I come across a customer that has a WEG, I will rewind and VPI. So far no failures on VPI'ed WEG...yet in the last 6 years.
Two things to be careful though is the metallurgy of the shaft. Typically they are not very good, at least what I have seen. Second is the core steel lamination coating. Some manufactures do not use any and depend on the 'mill scale' to provide the insulation. In rewinding, some shops use mechanical striping, this is OK, but some 'burn out' the insulation. If the WEG or any other motor has no lamination insulation and the core is burned out the motor becomes no good and un-repairable.

 

[jraef]

Thanks all for the feedback so far. I want to point out that my current application is for low voltage right now, so the VP issues are relatively moot. Good info for future reference though.

Any otyhers with LV experiences?

"Venditori de oleum-vipera non vigere excordis populi"

 

[electricpete]

That's the first I've heard of no C3 or C5 insulation on the laminations. But I don't doubt it.... Our local repair shop mentioned they sometimes put cores out in the weather to rust a little to improve the post-burnout core loss test results. (not that I'm saying it's a good idea).

Is there any way to tell by inspecting a core (prior to winding removal) whether or not it has core lam insulation?

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