Message Board Thread - "Thermal Survey for Localized Hot Spots within motor/ Opinions"

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Thermal Survey for Localized Hot Spots within motor/ Opinions MH 8/11/2004
I certified level 1 a couple of months ago so lack the experience of most on this message board. Therefore, I would welcome opinions on what I believe to be hot spots from crack or broken rotor bars of this motor. Data on motor follows. I am trying to develop the Thermography proof to back vibration data. I would welcome any critique or advice of this example or validity of this endeavor! Thanks for responds before!

Label Value
SP01 136.3°F
SP02 133.9°F
SP03 129.5°F
Vibration analysis has confirmed three broken rotor bars. Fp around three turning speed multiplies.

Spot temperatures are further conformation revealing localized heating, if I have interpreted thermal picture correctly.

All surfaces coated black reflective surfaces most unlikely. Camera’s angle manipulated up and down, side to side for conformation of no reflective signatures within thermal image survey.

US Electric
Rated 1750
Strobe @ 1783
HP 3
Frame 182T
Direct Drive Twin Impeller Vertically mounted.
 
Re:Thermal Survey for Localized Hot Spots within motor/ Opinions Edd Hindmarsh 9/4/2004
I survey quite a lot of motors in industry and in my opinion I do not think that you have localised hotspots, just a general overall temperature which is well within the temperature range of modern electric motors. Fractured or broken rotor bars would usually give a much higher temperature that would ventually burn out the stator winding. I think that to detect your problem thermographically you would need to remove the endshields and look at the bars directly
 
Re:Thermal Survey for Localized Hot Spots within motor/ Opinions Manuel 9/4/2004
i agree with Edd,

thermography shows no problem with this motor. so, maybe need to opened for close inspection,
how well balanced is the current at phases?

you note temperature difference on sp01 and sp02 with reference to sp03; this is due the conection box and flex conduit blocks the cooling air at that specific frame zones.

regards.
roberto manuel
thermoimagen
 


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