How long a motor should operate before cooling

Thread Starter


Joined May 26, 2012
My doubt is consider a motor of any specification (wattage) can operate continuously before it needs to be cooled? Or is it possible to design a motor which can operate continuously? I assume that in motor operation the hardware drive circuit also gets heated along with motor. If i provide proper heat dissipation is the continuous motor operation possible? Please advise.


Joined Mar 31, 2012
Well, since there are motors that operate continuously, it would seem fairly obvious that if proper heat dissipation is provided that continuous motor operations is possible. Of course, heat may not be the only thing preventing continuous operation, but it is certainly high on the list.

Any practical motor is going to generate heat. If that heat is carried away at a rate lower than it is generated, the temperature will rise, which will increase the rate at which heat is carried away. If the motor is capable of operating continuously at the equilibrium temperature profile, then no additional cooling is needed. If it can't, then additional cooling will be required.


Joined Jul 18, 2013
Most motors have a manufacturers spec that shows continuous torque, and peak torque values.
Continuous torque is the mode it can be operated in continuously without damage, and is directly relative to the current.
The Peak torque is the value that the motor should be operated in for only very brief period, otherwise it can lead to destruction.
In general, operating the motor continuously at the manuf. Current/Wattage rating shown on the motor plate should allow continuous operation.
But the operating situation should also be considered, open or enclosed space, ambient temp etc.


Joined Apr 5, 2008

I have seen many motors (like in roughpumps for vacuum) with forced air cooling using a fanblade on the rear axis of the motor.



Joined Jan 23, 2018
What are the other things i should think in continuous operation?
Most motors from the manufacturers that I have dealt with include a service rating, a duty factor, and a temperature rise with the other motor specifications. And some large motors also have a rating for the number of starts per hour. So you can select a motor rated for continuous duty with a given temperature rise, and if the temperature rise above the surrounding air is not above the maximum temperature rating then you are OK. But the big thing is the duty factor, some motors are not rated for continuous duty. Fan application motors are often rated as "continuous-air over", which means that if the motor is in the air stream it can run constantly.