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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