1. What is 3-Phase Power Calculation?

The 3-phase power calculation determines the real power (watts) delivered by a three-phase electrical system. It accounts for the phase relationship between voltage and current in balanced three-phase systems, which is common in industrial and commercial power distribution.

2. How Does the Calculator Work?

The calculator uses the 3-phase power formula:

Where:

• \( P \) — Real power in watts (W)
• \( V \) — Line-to-line voltage in volts (V)
• \( I \) — Current in amperes (A)
• \( PF \) — Power factor (unitless, 0 to 1)
• \( \sqrt{3} \) — Constant for 3-phase systems (≈1.732)

Explanation: The formula calculates the actual power being used (real power) as opposed to the apparent power (VA). The power factor accounts for the phase difference between voltage and current.

3. Importance of Power Factor

Details: Power factor represents the efficiency of power usage in an AC circuit. A PF of 1 means all power is real power (resistive load), while lower PF indicates reactive components (inductive or capacitive loads) that don't perform useful work but still draw current.

4. Using the Calculator

Tips:

• Enter line-to-line voltage (typically 208V, 240V, 380V, 400V, 480V, etc.)
• Measure current with a clamp meter or use rated current
• Power factor is often 0.8-0.95 for motors, 1.0 for resistive loads
• All values must be positive (PF between 0 and 1)

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between line-to-line and line-to-neutral voltage?
A: In 3-phase systems, line-to-line is voltage between two phases (higher), while line-to-neutral is between phase and neutral. This calculator uses line-to-line voltage.

Q2: How does this differ from single-phase power calculation?
A: Single-phase uses P = V × I × PF without the √3 factor. Three-phase is more efficient for power distribution.

Q3: What if I don't know the power factor?
A: For resistive loads (heaters, incandescent lights) use 1.0. For motors, 0.8 is a common estimate unless specified otherwise.

Q4: Can I use this for generator sizing?
A: Yes, but account for startup currents (typically 3-7x running current) and derating for altitude/temperature if applicable.

Q5: What about unbalanced 3-phase systems?
A: This calculator assumes balanced loads. For unbalanced systems, calculate each phase separately and sum the results.