How to Calculate AC Power Factor

Power Factor Formula:

\[ PF = \frac{\text{Real Power}}{\text{Apparent Power}} = \cos(\phi) \]

Power Factor (PF):

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1. What is AC Power Factor?

Power Factor (PF) is the ratio of real power to apparent power in an AC electrical system. It represents the efficiency of power usage and indicates how effectively electrical power is being converted into useful work output.

2. How Does the Calculator Work?

The calculator uses the power factor formula:

\[ PF = \frac{\text{Real Power}}{\text{Apparent Power}} = \cos(\phi) \]

Where:

\( PF \) — Power Factor (unitless, range: 0 to 1)
\( \text{Real Power} \) — Active power doing useful work (Watts)
\( \text{Apparent Power} \) — Total power in the circuit (Volt-Amperes)
\( \phi \) — Phase angle between voltage and current (degrees)

Explanation: Power factor measures the phase difference between voltage and current waveforms in AC circuits. A perfect power factor of 1 indicates all power is being used for useful work.

3. Importance of Power Factor Calculation

Details: Power factor calculation is crucial for electrical system efficiency, reducing energy costs, preventing equipment overload, and optimizing power distribution in industrial and commercial applications.

4. Using the Calculator

Tips: Enter real power in Watts, apparent power in VA, and optionally the phase angle in degrees. The calculator will compute power factor using either method. All power values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is a good power factor value?
A: Ideal power factor is 1.0. Values above 0.95 are considered good, while values below 0.85 may incur penalties from utility companies.

Q2: What causes low power factor?
A: Low power factor is typically caused by inductive loads like motors, transformers, and fluorescent lighting that create phase displacement.

Q3: How can power factor be improved?
A: Power factor correction involves adding capacitors to counteract inductive reactance, bringing the phase angle closer to zero.

Q4: What's the difference between real and apparent power?
A: Real power performs actual work, while apparent power is the vector sum of real and reactive power that the system must supply.

Q5: Why do utilities charge for poor power factor?
A: Low power factor requires utilities to generate and transmit more current for the same real power, increasing infrastructure costs and energy losses.