Motor Power Factor Calculator

What Is a Motor Power Factor

Power Factor Formula (3-Phase):

\[ PF = \frac{P_w}{V \times I \times \sqrt{3}} \]

Power Factor (PF):

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1. What is Motor Power Factor?

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 or other inductive load.

2. How Does the Calculator Work?

The calculator uses the formula for 3-phase systems:

\[ PF = \frac{P_w}{V \times I \times \sqrt{3}} \]

Where:

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

Explanation: The formula divides the real power by the product of voltage, current, and √3 to determine the power factor.

3. Importance of Power Factor

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

4. Using the Calculator

Tips: Enter the real power in watts, line voltage (default 480V for industrial systems), and line current in amps. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a good power factor value?
A: Ideally 0.95 or higher. Below 0.85 is generally considered poor.

Q2: Why is √3 used in the formula?
A: It accounts for the phase relationship in 3-phase systems. For single-phase, use PF = P/(V×I).

Q3: What causes low power factor?
A: Mainly inductive loads like motors and transformers operating at less than full load.

Q4: How can power factor be improved?
A: Through power factor correction capacitors or using more efficient motors.

Q5: What's the difference between real and apparent power?
A: Real power (watts) does actual work, while apparent power (VA) is the product of voltage and current.