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Old 06-01-2011, 05:56 AM   #8
brk-lnt
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Quote:
Originally Posted by Lakepilot View Post
Their data sheet indicates the 3/4 HP motor draws 4.7 amps while the 1/2 HP draws 5 amps.
Assuming 120V motors, the 3/4 HP unit would be operating at 100% efficiency to achieve 3/4 HP at a 4.7 amp draw. The 1/2 HP unit would be operating with 62% efficiency.

Horsepower ratings on small motors are almost always misleading, or misapplied.

1 HP = 746 watts. A standard 120V 15A circuit can supply 1800 watts (actually, less, you generally don't run a circuit continuously at it's max rating), or 2.4 Horsepower. That is assuming 100% efficiency (impossible) and not taking into account power factor.

They don't say how they got the ratings, but my guess is that the 3/4 HP unit would use more like 7-8 amps in operation.
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