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Anonymous Poster #1

Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/02/2016 2:45 AM

Hi! I have a great problem for dismantaling NDE ball bearing of 710kw 3.3kv WRIM driving water pump.(Bearing -228 ) .After I have disassembled carbon brush housing and end cover ,I found a serious rooted case of welded surfaces between bearing inner ring and rotor shaft..Is there any dangerious unseen Motor Shaft Current without using VFD. Motor and Starter are China made and run with simple vacuum cotactor and liquid resistance starter. I consider there may have best solution that I need be provided by one or more competent Engineers. Khinzawmyint ,AE ,Myanmar.
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SolarEagle
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Join Date: Mar 2007
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#1

Re: Great Problem of dismantling Bearing from 710kw 3.3kv WRIM

03/02/2016 3:29 AM

I would check for proper grounding and check voltage to motor for proper wave form and quality....are you using shielded cable? check test procedures listed in link below...

http://ecmweb.com/motors/diagnosing-understanding-motor-bearing-currents

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Anonymous Poster #1
#2
In reply to #1

Re: Great Problem of dismantling Bearing from 710kw 3.3kv WRIM

03/02/2016 7:54 AM

Motor well finished with 3C Armoured Cable , Cable shield grounded with a acceptable grounding resistance of 3 Ohms. Thank you for your sharp edge knowledge about Motor Bearing Current , that now I realized. Thanks. I will try for another possible remedies.
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TonyS
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#3

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/02/2016 9:15 AM

3Ω earth return for 3.3kV is way too high.

That doesn't address the problem of the bearings. Motors of that size will have circulating shaft current regardless of VSD's therefore one bearing should be isolated from earth. Have you tested the bearing isolation?

If you want more help then stop hiding in anonymity.

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Khinzawmyint
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#4
In reply to #3

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/02/2016 11:06 AM

YesSr Mr TonyS Pls let me know how many ohms does it need as a critical value ?.
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PWSlack
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#5

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/02/2016 6:45 PM

Do let the forum know how the telephone discussions with the motor manufacturer went.

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Neiljohn
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Location: England
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#6

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/03/2016 5:06 AM

This may be of interest: http://www.est-aegis.com/datasheets/AEGIS_PRO_Series_Best_Practices.pdf
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Nothing is Impossible
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Location: Sydney . Australia
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#7

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/03/2016 6:34 AM

Are you sure that you correctly understand the problem ? You say the bearing is welded to the shaft , do you mean the bearing inner ring has fused to the shaft because of a bearing lockup , or do you misunderstand the fact that the bearing will be an interference fit on the shaft ? If you removed the bearing from the shaft with a puller is there heat marks and scoring on the shaft ? I don't think he problem here has been accurately described .
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Khinzawmyint
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#8
In reply to #7

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/03/2016 1:29 PM

Really, the 710 kw Motor is a another problematic moter prior to that case we had failed in successful dismantling of NDE bearing ranging 250kw ,3.3 kv WRIM .Using applied successive mechanical tools , welding machine , wheel puller and impacts to pull out bearing inner ring stuck firmly to the motor shaft. It looks like a phenomenna of overheating of different two metals rather than crowded pitting occurred probably by long term discharge currents. This motor shaft was then usellessly wounded with mechanical defects and assigned for refit. Doing at work site can't get good performance. Last 15 years ago at my worksite of ' electric motor villages ' 22kw Fimet Italy motors running in full SF @ up to 22 hours per day , rarely suffered the same problem , due to having small weight we replaced with new Motor Rotor spares. Now , I had recently designed a small versatile machine that can work like a small lathe machine cutting ,trimming and smoothing to make shaft area around the bearing without becoming deformation.But my project was at the stage of Planning. Thanks for all competent persons wearing me ahead modern technological ideas ,resources especially of kindness. *** * Great Britain is originally Grate. Great Walls were intended for . . . " I want to say there is no ignorence of doing Great thing which can't be assumed as a small Matter"
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Nothing is Impossible
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#9
In reply to #8

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/03/2016 4:53 PM

Show us photos of the shaft and bearing. If the shaft showed overheating it is because the bearing inner race. Was spinning on the shaft. Either the bearing seized up or the bearing didn't have correct tolerance from new and was loose on the shaft leading to spin , then overheating. Was the bearing internals damaged ? Electrical issues I think will not cause such a problem
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Khinzawmyint
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#10
In reply to #9

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/04/2016 2:02 AM

I wiil try to show photos later. Thanks.
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Khinzawmyint
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#11
In reply to #9

Re: Great Problem of Dismantling Bearing from 710kw 3.3kv WRIM

03/04/2016 2:53 PM

Photos of 710 kw -3.3kv get at ( wrud.tpsk @gmail.com ) pass word ( 25033MOT )
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Users who posted comments:

Anonymous Poster (1); Khinzawmyint (4); Neiljohn (1); Nothing is Impossible (2); PWSlack (1); SolarEagle (1); TonyS (1)

Previous in Forum: Line Impedance Resonance Analysis   Next in Forum: Problems Faced in VT Ratio Test

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