1. What is Power Factor for a 3-Phase Motor?

Definition: Power factor (PF) is the ratio of real power (watts) to apparent power (volt-amps) in an AC electrical system.

Purpose: It measures how effectively electrical power is being used by a motor, with 1.0 being perfect efficiency.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( PF \) — Power factor (unitless, between 0 and 1)
• \( P_w \) — Real power (watts)
• \( V \) — Voltage (volts)
• \( I \) — Current (amps)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula calculates the ratio between the actual power being used (watts) and the apparent power (volt-amps) being supplied.

3. Importance of Power Factor

Details: A high power factor (close to 1) indicates efficient power usage, while a low power factor means poor efficiency and possible penalties from utilities.

4. Using the Calculator

Tips: Enter the motor's real power in watts, operating voltage (default 480V for industrial motors), and current draw in amps. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical power factor for motors?
A: Induction motors typically have 0.85-0.90 PF at full load, dropping to 0.2-0.3 at no load.

Q2: Why is √3 used in the formula?
A: The √3 factor accounts for the phase difference in 3-phase power systems.

Q3: How can I improve power factor?
A: Use power factor correction capacitors, properly size motors, and avoid running motors lightly loaded.

Q4: What's the difference between single-phase and 3-phase PF calculation?
A: For single-phase, omit the √3 factor (use PF = P/(V×I)).

Q5: Can power factor be greater than 1?
A: No, theoretically PF ranges from 0 to 1, though measurement errors might show values slightly above 1.