Motor current calculator
A motor draws the power it delivers, plus its losses, divided by voltage and power factor.
kW
V
%
Full-load current
14.151A
- Electrical input power
- 8333.333
- Apparent power
- 9.804 kVA
- Shaft power in horsepower
- 10.058
- Losses as heat
- 833.3
- Typical direct-on-line starting current Six times full load is a common figure; check the motor data plate.
- 84.9 A
Show the working
- Shaft power = 7.5
- Voltage = 400
- Supply = 3
- Efficiency = 90
- Power factor = 0.85
- Electrical input power = 7.5 * 1000 / (90/100) = 8333.33
- factor = 3 == 3 ? sqrt(3) : 1 = 1.732 05
- Full-load current = 8333.33 / (1.732 05 * 400 * 0.85) = 14.1507
- Apparent power = 8333.33 / 0.85 / 1000 = 9.803 92
- Shaft power in horsepower = 7.5 * 1000 / 745.69987158227022 = 10.0577
- Losses as heat = 8333.33 - 7.5*1000 = 833.333
- Typical direct-on-line starting current = 14.1507 * 6 = 84.9045
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- input power = shaft power / efficiency
- three phase: I = P / (sqrt(3) V pf)
- single phase: I = P / (V pf)