Karl Townsend wrote:
My apple water bin dump uses a .5 horse 3 phase 220 VAC motor attached by
pulleys and belt to an outboard motor prop in a tube to pump water. Maybe
1"
head at 100+ GPM. I just measured the current draw on this motor at 1.5
amp,
2.0 amp, and 2.2 amp with a clamp A-meter.

Na, I'm not totally re doing something that has run 20 years. But I'd like
to try a different prop - it might be better. If not, I'll go back. My only
question is if this motor will have enough power at 1/2 speed. Do you know
how to figure that?



I can guarantee you will not get 1/2 Hp out of a 1/2 Hp-rated motor at
30 Hz. You will get 1/4 Hp at rated load. It scales linearly with
frequency (speed) below the rating point. If you try to load the motor
to the rated mechanical output, it will draw twice the rated input
current (roughly) and smoke.

Jon