Power Factor Calculator

Calculate Power Factor

How to Calculate Power Factor

Power factor is a crucial concept in electrical engineering that measures how efficiently electrical power is being used in a circuit. It is the ratio of real power to apparent power in an electrical system.

Power Factor Formula

The formula to calculate power factor is:

\[PF = \frac{P}{S}\]

Where:

  • PF is the power factor
  • P is the real power in watts (W)
  • S is the apparent power in volt-amperes (VA)

Calculation Steps

  1. Determine if the system is single-phase or three-phase
  2. Measure or obtain the real power (P) in watts
  3. Measure or obtain the current (I) in amperes
  4. Measure or obtain the voltage (V) in volts
  5. Calculate the apparent power (S) using S = VI for single-phase or S = VI√3 for three-phase
  6. Calculate the power factor using PF = P / S
  7. Calculate the reactive power using Q = √(S² - P²)
  8. If needed, calculate the correction capacitance to improve the power factor

Example Calculation

Let's calculate the power factor for a single-phase system:

  • Real Power (P): 1000 W
  • Current (I): 5 A
  • Voltage (V): 230 V
  1. Calculate apparent power: \[S = VI = 230 \text{ V} \times 5 \text{ A} = 1150 \text{ VA}\]
  2. Calculate power factor: \[PF = \frac{P}{S} = \frac{1000 \text{ W}}{1150 \text{ VA}} \approx 0.87\]
  3. Calculate reactive power: \[Q = \sqrt{S^2 - P^2} = \sqrt{1150^2 - 1000^2} \approx 565 \text{ VAR}\]

Therefore, the power factor of this system is approximately 0.87.

Power Triangle Visualization

Real Power (1000 W) Reactive Power (565 VAR) Apparent Power (1150 VA) Power Triangle

This power triangle visually represents the relationship between real power (green), apparent power (red), and reactive power (blue). The angle between the apparent power and real power represents the power factor angle.

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