Induction Motor Heat Generation Calculation
Induction Motor Heat Generation Calculation
(OP)
1st time having to do this and schooling is a little rusty and don't think we even touched this in schooling.
I have been asked to calculate how much heat a group of newly installed motors will generate into the surrounding room.
I figured I could just use the motor eff and then calculated the wasted wattage, this was shot down by my supervisor, he stated that the heat generated would be much lower then this and to try finding a thermal model of an induction motor,
If someone could point me towards an informative web site or even a technical paper on calculating heat losses in motors that would be great.
Thanks
Hank
I have been asked to calculate how much heat a group of newly installed motors will generate into the surrounding room.
I figured I could just use the motor eff and then calculated the wasted wattage, this was shot down by my supervisor, he stated that the heat generated would be much lower then this and to try finding a thermal model of an induction motor,
If someone could point me towards an informative web site or even a technical paper on calculating heat losses in motors that would be great.
Thanks
Hank





RE: Induction Motor Heat Generation Calculation
In steady state, the main things you need to know about the motor are :
1 - motor load level
2 - motor efficiency at that load level
You might make determining motor efficiency a little more complicated if you have knowledge about voltage deviations or votlage unbalance, but that is a refinement.
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RE: Induction Motor Heat Generation Calculation
RE: Induction Motor Heat Generation Calculation
OEM's do temperature rise test for motors and generators, which is quite complicated and expensive. Hence, it is only done as a type test.
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RE: Induction Motor Heat Generation Calculation
If I get an explanation from him as to what he was thinking I will post it.
Hank
RE: Induction Motor Heat Generation Calculation
Here is a decent resource for you. On the 2nd page they describe methods of determining motor efficiency if you don't already know it. I suggest getting their MotorMaster software. It used to be free, I don't know if it still is, but I doubt it is expensive.
h
This paper goes into more depth if you want to do it on your own.
http://w
RE: Induction Motor Heat Generation Calculation
RE: Induction Motor Heat Generation Calculation
RE: Induction Motor Heat Generation Calculation
RE: Induction Motor Heat Generation Calculation
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Induction Motor Heat Generation Calculation
I suppose some heat from the motor could be conducted through the shaft, into the pump and on to the fluid being pumped and then on to who knows where, but it is still starts as heat from the motor.
RE: Induction Motor Heat Generation Calculation
Multiply these numbers by the loading factor on the motor to get an approximate answer. The tricky part is determining where the work goes, inside or outside the room.
See attached.
RE: Induction Motor Heat Generation Calculation
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Induction Motor Heat Generation Calculation
Just need a rough calculation so that we know how many changes of air are required in the building
RE: Induction Motor Heat Generation Calculation
Remember all the work winds up as heat also, just draw a box around your building or room and calculate the energy balance. If you are pumping or conveying outside the room then the work is going out. The exception to this would be a conveyor that is half in or half out of the room, then about 50% of the load would be in the room depending on where the motor was located. For pumps the inefficiency of the pump goes to heating the liquid which usually leaves the room (unless it is recirculated) so that energy does not stay in the room. The rest of the energy goes to overcoming friction which turns to heat and is usually carried away by the fluid. Energy used to lift the elevation of the fluid is stored and then released once it returns to its original elevation (if it does).
RE: Induction Motor Heat Generation Calculation
RE: Induction Motor Heat Generation Calculation
In that case, use jraef's analysis for the motor's heat input into the room and then consult the gearbox manufacturer for its losses at the speed and torque that you feel would be appropriate for its worst case continuous operation.
As for all this talk of energy being converted into heat in the load, it is technically correct but usually not a factor unless, as stated above, the energy is dissapated in the same enclosure as the motor/gearbox.