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Old 05-10-2018, 02:15 PM   #6 (permalink)
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Originally Posted by Ecky View Post
I'm not sure what benefits there would be to lowering its RPM, unless perhaps it's more efficient at one RPM than another.
It's output is limited at lower RPMs. It will try to make up for it by boosting the field voltage, but it will hit a wall/limit and not be able to output any more without spinning faster. (as shown by cars with small alternators that can barely keep the voltage up at idle with a decent load put on)

Rather like an engine, it will have maximum efficiency when kept close to it's peak output. Peak output for a given RPM will always be better than partial at a higher RPM.

Plus, hey, they usually have fans build on/in them, so there will be a tiny bit less power "wasted" by the fan spinning slower.
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