Comment by taneq
5 days ago
The other aspect is that a smaller motor with the same power generally has higher efficiency, by necessity, since it has less heat dissipation. So higher power and higher efficiency and lower size/weight all go together. It’s a great synergy.
Is it always true that a smaller motor with the same power has less heat dissipation? It doesn't seem all that obvious to me.
All else held equal, I think so, yeah. If you have the same temperature differential, the same manner of heat dissipation, and a smaller surface area then that should mean smaller heat dissipation, yeah?
Obviously if you go from eg. a large air-cooled motor to a smaller water-cooled motor, then the smaller motor could potentially dissipate more heat, but that's a different scenario.
We only know that the large and the small motor deliver the same power. I don't see how we can conclude from that the temperature differential is also equal. In fact I would expect a smaller motor to have a larger temperature differential, because the heat is produced concentrated in a smaller volume.
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