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Old 12-12-2009, 12:39 AM   #4 (permalink)
gone-ot
...beats walking...
 
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...DC motors are fairly efficient (~85-95%) but their fan blades are NOT! So, total electrical power (HP.e) will be greater than the true mechanical power (HP.m) needed to move a given volume of air...that is, you're gonna put "in" more HP than you effectively get "out," ie:

efficiency = Power OUT / Power IN = (HP.m / HP.e)
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