Three-Phase Power Calculator

What is Three-Phase Power?

Three-phase power is the standard for industrial and commercial electricity supply worldwide. Three sinusoidal voltages, 120° apart in phase, provide more efficient power transmission, smoother motor operation, and higher power density than single-phase systems.

Three-Phase Power Formulas

For balanced three-phase loads:

• Apparent Power: S = √3 × V_line × I_line (VA)
• Real Power: P = √3 × V_line × I_line × PF (W)
• Reactive Power: Q = √3 × V_line × I_line × sin(φ) (VAR)

Line vs Phase relationships:

• Delta connection: V_line = V_phase; I_line = √3 × I_phase
• Star (Wye) connection: V_line = √3 × V_phase; I_line = I_phase

How to Use This Calculator

Enter line voltage, line current, and power factor. Select star or delta connection. The calculator returns all three power quantities and phase values.

Practical Examples

Example 1: 415V three-phase supply, 50A line current, PF 0.9. Real Power = √3 × 415 × 50 × 0.9 = 32.3 kW.

Example 2: 200kW motor at 400V, PF 0.85. Line current = 200,000 / (√3 × 400 × 0.85) = 339A — critical for cable and switchgear sizing.

Applications

Three-phase calculations are essential for: industrial motor drives, data centre power infrastructure, EV charging stations, renewable energy inverter output, and transformer sizing.