effect of ambient temperature on the motor 3

[ele.engineer]

Hello Experts:
we have a 3 phase motor working at ambient temperature about 55 deg. Celsius (attached name plate data)
what is the effect of the ambient temperature on the motor at the long term

 

[djs]

The insulation life will be greatly shortened. I think that the rule of thumb is half for each 10C above rating.

 

[Compositepro]

The horsepower rating of the motor will also be reduced. The rating is determined by how much heat can be dissipated before the hotest spot in the motor reaches destructive levels. The name plate power is based on an ambient temperature assumption, which I believe is usually 40C.

 

[electricpete]

It's an either/or, not an also.
(If you derate to maintain estimated insulation temperature below rated, there is no expected loss of life.)


=====================================
(2B)+(2B)' ?

 

[edison123]

Motor standards are for a maximum ambient of 40 deg C. If I remember right, for every 1 deg C above 40 deg C, the motor must be derated by 1%. So, in your case, if your driven load requires X KW, you would be better off buying motor with 1.15X KW rating.

Muthu

http://www.edison.co.in

 

[GroovyGuy]

Hi Mohamad,
What you have here is a USA-made motor, with CSA certification and rated 415V; a small world . . .
I checked NEMA-MG1, the governing standard for this motor, for ambients > 40C, and all I could find is:

Temperature Rise for Ambients Higher Than 40°C
The temperature rises given in Table 31-2 are based upon a reference ambient temperature of 40°C.
However, it is recognized that induction machines may be required to operate in an ambient temperature
higher than 40°C. For successful operation of induction machines in ambient temperatures higher than
40°C, the temperature rises of the machines given in Table 31-2 shall be reduced by the number of
degrees that the ambient temperature exceeds 40°C. When a higher ambient temperature than 40°C is
required, preferred values of ambient temperatures are 50°C , 65°C , 90°C , and 115°C.

Overall, unless this motor has been derated, it won't be with us for long in a 55C ambient. Are there other mitigating circumstances (ie elevation > 1000m, or inverter operated).
Did you check with Reliance, the motor OEM. I'm sure they have mortality data for high ambient temperatures.

See also

http://www.eng-tips.com/viewthread.cfm?qid=176014

 

[Hoxton]

Please remember that ambient temperature in this context is the cooling air inlet to the motor.