| To Find | Direct Current | Alternating Current | ||
|---|---|---|---|---|
| Single Phase | Two-Phase* Four-Wire | Three Phase | ||
| Amperes when Horsepower is known |
HP x 746
E x EFF |
HP x 746
E x EFF x PF x 2 |
HP x 746
2 x E x EFF x PF |
HP x 746
E x EFF x PF x 1.73 |
| Amperes when Kilowatts are known |
KW x 1000
E |
KW x 1000
E x PF |
KW x 1000
2 x E x PF |
KW x 1000
E x PF x 1.73 |
| Amperes when "KVA" is known |
KVA x 1000
E |
KVA x 1000
|
KVA x 1000
E x 1.73 |
|
| Kilowatts |
E x I
1000 |
E x I x PF
1000 |
I x E x 2 x PF
1000 |
E x I x 1.73 x PF
1000 |
| Kilovolt-Amperes "KVA" – |
I x E
1000 |
I x E x 2
1000 |
E x I x 1.73
1000 |
|
| Horsepower (Output) |
E x I x EFF
746 |
E x I x EFF x PF
746 |
I x E x 2 x EFF x PF
746 |
E x I x EFF x PF x 1.73
746 |
|
E = Voltage |
||||
Note: Direct current formulas do not use (PF, 2, or 1.73)
- Single phase formulas do not use (2 or 1.73)
- Two phase-four wire formulas do not use (1.73)
- Three phase formulas do not use (2)
- * For three-wire, two phase circuits the current in the common
conductor is 1.41 times that in either of the other two conductors.