Pure theory math is...
746 watts per HP
746 x 1/2 = 373
373 x 3 hrs = 1119 kw = 1.2 KWHr
Now, reality check....
either clamp the feed, or use the nameplate amperage and plug those numbers in....
xx amps times 240 volts = actual wattage, times the 3 hours
Multiply the results by the KWHr fees charged by the local POCO.
PS: You could check into the Technical Forums here for any additional formulas you may need. Or, post away!
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Last edited by HotLine1; 06/04/07 08:09 AM. Reason: Added a "PS"