POWER FORMULAS FOR ELECTRIC MOTORS
| TO FIND | DIRECT CURRENT | SINGLE PHASE | THREE PHASE |
| HORSE POWER |
E x I x EFF |
E x I x EFF x PF |
1.732 x E x I x EFF x PF 746 |
| CURRENT | 746 x HP E x EFF |
746 x HP E x EFF x PF |
746 x HP 1.732 x E x EFF x PF |
| EFFICIENCY | 746 x HP E x I |
746 x HP E x I x PF |
746 x HP 1.732 x E x I x PF |
| POWER FACTOR | Input Watts E x I |
Input Watts 1.732 x E x I |
E = Volts I = Amperes Eff = Efficiency (decimal) HP = Horsepower PF = Power Factor (decimal)
OUTPUT FORMULAS FOR ELECTRIC MOTORS
| HORSEPOWER |
Torque (lb.ft) x RPM |
| KILOWATTS | Torque (N.m) x RPM 9550 |
| TORQUE(lb.ft) | Horsepower x 5250 RPM |
| TORQUE (N.m) | Kilowatts x 9550 RPM |
SPEED FORMULAS FOR AC MACHINERY
| Synchronous RPM |
120 x Frequency (Hz) |
| Percent Slip |
Synchronous RPM - Full-Load RPM
x 100Synchronous RPM |
FORMULAS FOR ELECTRIC CIRCUITS
| TO FIND | DIRECT CURRENT | SINGLE PHASE | THREE PHASE |
| AMPERES |
Watts |
Watts |
Watts |
| VOLT- AMPERES | Volts x Amperes | 1.732 x Volts x Amperes | |
| WATTS | Volts x Amperes | Volts x Amperes x Power Factor | 1.732 x Volts x Amperes x Power Factor |
OHMS LAW
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Ohms = Volts/Amperes (R=E/I) |
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Amperes = Volts / Ohms (I=E/R)
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Volts = Amperes x Ohms (E=IR)
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