Frame temperature of the motor

[PAP]

Dear all
Have anyone ever see the recommended standards or best practice for the frame temperature of the induction motor? Please give me your recommendations or resources about this topic.
Thank you.

 

[jbartos]

Suggestion: Frame temperature of the induction motor is supposed to be in a proper alignment with the winding Insulation Class system, which is governed by industry standards, e.g. IEEE, NEMA, ANSI, etc.

 

[jOmega]

Gosh JB,

Where'd you pull that one from ?

I don't think NEMA, IEC, EASA etc. would agree.

Can you site some references where such a position is stated ?

 

[electricpete]

I would agree with jOmega that this is not a parameter specified in the standards.

Regarding localized heating in the area of the bearing, you may expect frame temperature to be APPROX 10-20F cooler than the bearing itself metal itself (in this area). Somewhere around 180F frame temperature at this location (200F bearing temperature), I would start to get concerned about the bearing lubrication.

As far as what delta-T is expected between the frame and the winding, I think you may expect a very wide range maybe 10F - 100F. So the most useful parameter of course is trending a given motor (at constant load) over time, or comparision with sister units of same type.

You can also look at the motor current, and inspect the environement cooling ducts as indirect indication of whether you expect overheating. If it's an open drip-proof motor in a dirty area, it should be cleaned periodically.