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Electric Motor Power Factor Calculator

How to Calculate Motor Power Factor

The Motor Power Factor Calculator determines the power factor (cos ϕ) using rearranged FLA formulas:

Single-Phase AC (kW):

\( \cos \phi = \frac{P [kW] \times 1000}{V \times I \times \eta} \)

Single-Phase AC (HP):

\( \cos \phi = \frac{P [HP] \times 746}{V \times I \times \eta} \)

Three-Phase AC (kW):

\( \cos \phi = \frac{P [kW] \times 1000}{V \times 1.732 \times I \times \eta} \)

Three-Phase AC (HP):

\( \cos \phi = \frac{P [HP] \times 746}{V \times 1.732 \times I \times \eta} \)

Where:

  • \( \cos \phi \): Power factor (decimal).
  • \( P [HP] \), \( P [kW] \): Motor power rating (HP or kW).
  • \( V \): Voltage (Volts).
  • \( I \): Amps (A).
  • \( \eta \): Efficiency (decimal).
  • 1.732: Approximation of √3.
  • 1000: kW to W conversion.
  • 746: HP to W conversion.

Enter the values to compute the power factor.

Using the Motor Power Factor Calculator

This tool helps calculate the power factor for motor systems based on provided parameters.

Input power, unit, voltage, amps, efficiency (default: 0.85), and phase type. Outputs power factor.

Example: For 5 HP single-phase, 230 V, 23.860 A, 0.85 efficiency.

  1. Power: 5 HP
  2. Voltage: 230 V
  3. Amps: 23.860 A
  4. Calculation: \( \cos \phi = \frac{5 \times 746}{230 \times 23.860 \times 0.85} = 0.800 \)
  5. Result: 0.800

Ideal for electrical analysis.

Common FAQ

  • Q: What does power factor indicate?
    A: Ratio of real to apparent power, affecting efficiency.
  • Q: Why rearrange FLA formulas?
    A: To solve for PF from known FLA values.
  • Q: Single vs. three-phase difference?
    A: Three-phase includes 1.732 (√3) factor.
  • Q: Accuracy?
    A: Precise with standard conversions, rounded to 3 decimals.
  • Q: PF >1?
    A: Impossible; check inputs if occurs.
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