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Motor Power Calcs


Does 22 formulas seem like too many? Look close and you'll find a pattern. They are all variants of only 6 formulas.

When you go from DC to 1 phase, you have to factor in Power Factor (PF).

Then when you move up to 3 wire, single phase, you simply double your voltage relative to ground.

A 3 phase system feeds your motor from 3 different wires with phases seperated by 120 degrees so you use a multiplier of 1.73 rather then 2.


Find Amps with HP Amps with KW Amps with KVA KW KVA HP
DC HP x 746
E x %Eff
KW x 1000
E

E x I
1000
E x I x %Eff
746
Single Phase HP x 746
E x %Eff x PF
KW x 1000
E x PF
KVA x 1000
E
E x I x PF
1000
E x I
1000
E x I x %Eff x PF
746
1 Phase, 3 Wire HP x 746
E x %Eff x PF x 2
KW x 1000
E x PF x 2
KVA x 1000
E x 2
E x I x PF x 2
1000
E x I x 2
1000
E x I x %Eff x 2 x PF
746
3 Phase HP x 746
E x %Eff x PF x 1.73
KW x 1000
E x PF x 1.73
KVA x 1000
E x 1.73
E x I x PF x 1.73
1000
E x I x 1.73
1000
E x I x %Eff x 1.73 x PF
746

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