1. What is Power Factor for 3-Phase Induction Motors?

Definition: Power factor (PF) is the ratio of real power (watts) to apparent power (volt-amps) in an AC circuit, indicating how effectively electrical power is being used.

Purpose: It helps electrical engineers and technicians assess motor efficiency and power quality in three-phase systems.

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)
• \( V \) — Line voltage (volts)
• \( I \) — Line current (amps)
• \( \sqrt{3} \) — Constant for three-phase systems (≈1.732)

Explanation: The formula divides the real power by the product of voltage, current, and √3 (which converts line quantities to phase quantities in three-phase systems).

3. Importance of Power Factor Calculation

Details: A high power factor (close to 1) indicates efficient power usage, while low power factor means poor utilization and may incur utility penalties.

4. Using the Calculator

Tips: Enter the motor's real power in watts, line-to-line voltage in volts, and line current in amps. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a good power factor for induction motors?
A: Typically 0.85-0.95 at full load. Lower at light loads due to magnetizing current.

Q2: Why is √3 used in the formula?
A: It converts between line and phase quantities in balanced three-phase systems.

Q3: How can I improve power factor?
A: Use power factor correction capacitors, avoid motor over-sizing, and maintain proper loading.

Q4: Does this work for single-phase motors?
A: No, for single-phase omit the √3 factor (PF = P/(V×I)).

Q5: What causes low power factor?
A: Induction motors inherently have lagging PF due to magnetizing current. Light loading worsens it.