how hot can a motor run 2

[bigwilly104]

I have a 2/4 HP. GE motor that is part of a York commercial air conditioner. it runs the prop fan for the condensor. It is a sealed case motor with sealed berings. 208-230 1 ph with a 10/370 run cap. Insulation class B. This is a new motor. I am reading 190 deg F on the outside of the case with a wire thermister taped to the side. This is a air over motor so when I shut the unit down it will climb as high as 210 deg. This is the second motor I have had in the machine in a week and it is stil running. The first replacement motor lost the seal on the shaft end berings and got a bit stiff. I checked with York to make sure this was the same type of motor. Also the amp draw is 3.5 and the name plate shows 4.7 RLA. I cant get the manufacturer of the motor to call back GE is having a company called Regal-Beloit make the motors so tech questions go to them. INPUT PLEASE

 

[Skogsgurra]

190 F is just under 90 C. Class B insulation can run at 130 C hot spot. The hot spot is usually 10 - 20 K above outside of case so you do not have more than 100 - 110 C in the hot spot.

There should not be a problem with the insulation. But there are other things to consider. Like bearing grease getting hot (rotor losses make shaft hotter than motor) and the bearing seal, which seems to be above its normal operating temperature. There are metal seals.

Still, I think that a motor should not run so hot that you can fry eggs on them. What is your ambient? Is air circulation as it should? What about your voltage? A low voltage does exactly this to a motor. Slip losses get high and that heats the rotor.

Gunnar Englund

http://www.gke.org

 

[aolalde]

Motors are designed now days to run very close to the materials allowed limits. This motor is designed for 80°C rise over maximum 40°C ambient. So at full load the windings could reach 120°C (248 F)average. The bearings, grease and other elements are designed to match the operating temperature. As far as the voltage value and balance, frequency, ambient and load are kept into standard limits, the motor should achieve at least "the basic rating life L10 of 20,000 hrs".

 

[jasongreat1]

I see that airflow has already been mentioned above,but
what altitude are you at? Thinner air = less cooling

 

[bigwilly104]

only 160' above sea level