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| AC/DC Formulas | ||||
| To Find | Direct Current | AC
/ 1phase 115v or 120v |
AC
/ 1phase 208,230, or 240v |
AC
3 phase All Voltages |
| Amps
when Horsepower is Known |
HP x 746 E x Eff |
HP x 746 E x Eff X PF |
HP x 746 E x Eff x PF |
HP x 746 1.73 x E x Eff x PF |
| Amps
when Kilowatts is known |
kW x 1000 E |
kW x 1000 E x PF |
kW x 1000 E x PF |
kW x 1000 1.73 x E x PF |
| Amps when kVA is known |
kVA x 1000 E |
kVA x 1000 E |
kVA x 1000 1.73 x E |
|
| Kilowatts | I x E 1000 |
I x E x PF 1000 |
I x E x PF 1000 |
I x E x 1.73 PF 1000 |
| Kilovolt-Amps | I x E 1000 |
I x E 1000 |
I x E x 1.73 1000 |
|
| Horsepower (output) |
I x E x Eff 746 |
I x E x Eff x PF 746 |
I x E x Eff x PF 746 |
I x E x Eff
x 1.73 x PF 746 |
| Three Phase Values |
| For 208 volts x 1.732,
use 360 For 230 volts x 1.732, use 398 For 240 volts x 1.732, use 416 For 440 volts x 1.732, use 762 For 460 volts x 1.732, use 797 For 480 Volts x 1.732, use 831 |
E = Voltage / I = Amps /W = Watts / PF = Power Factor / Eff = Efficiency / HP = Horsepower
| AC Efficiency and Power Factor Formulas | ||
| To Find | Single Phase | Three Phase |
| Efficiency | 746 x HP E x I x PF |
746 x HP E x I x PF x 1.732 |
| Power Factor | Input Watts V x A |
Input Watts E x I x 1.732 |
| Power - DC Circuits |
| Watts = E xI |
| Amps = W / E |
| Ohm's Law / Power Formulas | |
 |
P = watts
I = amps R = ohms E = Volts |
| Voltage Drop Formulas | |||||
| Single
Phase (2 or 3 wire) |
VD = | 2 x K x I x L CM |
K
= ohms per mil foot (Copper = 12.9 at 75°) (Alum = 21.2 at 75°)
L = Length of conductor
in feet |
||
| CM= | 2K x L x I VD |
||||
| Three Phase | VD= | 1.73 x K x I x L CM |
|||
| CM= | 1.73
x K x L x I VD |
||||
If there is anything you would like to add or if you have any comments please feel free to email the Webmaster at webmaster@keystone-electric.com.