IEC Supply, LLC - Automation and Control Specialists

Commonly Used Formulas
Efficiency =

746 x Output Horsepower

Input Watts
Three-Phase
Kilowatts		 =
Volts x Amperes x Power Factor x 1.732
1000
Three-Phase
Volt-Amperes		 = Volts x Amperes x 1.732
Three-Phase
Amperes		 =
746 x Horsepower
1.732 x Volts x Efficiency x Power Factor
Three-Phase
Efficiency		 =
746 x Horsepower
Volts x Amperes x Power Factor x 1.732
Three-Phase
Power Factor		 =
Input Watts
Volts x Amperes x 1.732
Single-Phase
Kilowatts		 =
Volts x Amperes x Power Factor
1000
Single-Phase
Amperes		 =
746 x Horsepower
Volts x Efficiency x Power Factor
Single-Phase
Efficiency		 =
746 x Horsepower
Volts x Amperes x Power Factor
Single-Phase
Power Factor		 =
Input Watts
Volts x Amperes
Horsepower
(3-Phase)		 =
Volts x Amperes x 1.732 x Efficiency x Power Factor
746
Horsepower
(1-Phase)		 =
Volts x Amperes x Efficiency x Power Factor
746
Ohms = Volts / Amperes (R = E / I)
Amperes = Volts / Ohms (I = E / R)
Volts = Amperes x Ohms (E = IR)
Ohms Law Calculator
VOLTS=Voltage, AMPS=Current, OHMS=Resistance, WATTS=Power
Enter any TWO numeric values and the calculator will give you all FOUR. Press the Calculate button after you have made your entries:
Volts Amps Ohms Watts

Watts = Volts x Amperes (W = EI)
Amperes =

Watts

     (I = W / E)

Volts
Horsepower =
Volts x Amperes x Efficiency
746
Synchronous
RPM		 =
Hertz x 120
Poles
Percent Slip =

Synch RPM - Full-Load RPM

   x 100

Synchronous RPM
Full Load Currents 3FLC
Three-Phase A-C Induction
Squirrel Cage and Wound Rotor Motors
HP 115V 200V 230V 460V 575V 2300V 4000V
1/2 4 2.3 2 1 8
3/4 5.6 3.2 2.8 1.4 1.1
1 7.2 4.15 3.6 1.8 1.4
1-1/2 10.4 6 5.2 2.6 2.1
2 13.6 7.8 6.8 3.4 2.7
3 11 9.6 4.8 3.9
5 17.5 15.2 7.6 6.1
7-1/2 25 22 11 9
10 32 28 14 11
15 48 42 21 17
20 62 54 27 22
25 78 68 34 27
30 92 80 40 32
40 120 104 52 41
50 150 130 65 52
60 177 154 77 62 16 8.8
75 221 192 96 77 20 11
100 285 248 124 99 26 14.3
125 358 312 156 125 31 18
150 415 360 180 144 37 20.7
200 550 480 240 192 49 27.6
Over 200HP Approx AmpsHP 2.75 2.4 1.2 .96 .24 .14
1FLC
Full Load Currents
Single-Phase A-C Motors
HP 115V 200V 230V
1/8 4.4 2.5 2.2
1/4 5.8 3.3 2.9
1/3 7.2 4.1 3.6
1/2 9.8 5.6 4.9
3/4 13.8 7.9 6.9
1 16 9.2 8
1-1/2 20 11.5 10
2 24 13.8 12
3 34 19.6 17
5 56 32.2 28
7-1/2 80 46 40
10 100 57.5 50
Torque (lb-ft) =
Horsepower x 5250
RPM
Horespower =

Torque (lb-ft) x RPM

   

5250
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