Three Phase Calculator
Find three-phase real power.
Three-phase power delivers more energy efficiently using three AC waveforms.
How the Math Works
The Three Phase Calculator uses the fundamental formula P = √3·V_L·I_L·PF to determine real power in three-phase electrical systems. Here, √3 (approximately 1.732) arises from the geometric relationship between three sinusoidal voltages separated by 120 degrees. V_L represents line voltage measured between any two conductors, I_L is the line current flowing through each conductor, and PF denotes power factor—the ratio of real power to apparent power, ranging from 0 to 1. Multiplying these components accounts for both the instantaneous energy transfer and the efficiency of power utilization across all three phases.
Practical Applications
To apply this calculator, first measure or obtain the line voltage between any two phases using a multimeter, typically 120V, 208V, 240V, 480V, or higher depending on your system. Next, determine the line current by measuring the current in any single conductor, which will be identical in balanced three-phase systems. Finally, identify the power factor from equipment nameplate data, utility bills, or a power quality analyzer. For example, a 480V motor drawing 25A with a power factor of 0.85 yields P = 1.732 × 480 × 25 × 0.85 = 17,639 watts or 17.6 kilowatts.
Day-to-Day Use
This calculation directly impacts your daily life by ensuring your electrical systems operate efficiently and safely. When sizing electrical panels, transformers, or backup generators, understanding actual power consumption prevents costly undersizing that could cause outages or oversizing that wastes investment. It also helps explain why your electricity bill reflects real power usage rather than apparent power, as low power factor charges incur additional fees. For homeowners with electric vehicles, home workshops, or medical equipment, this knowledge ensures proper circuit protection and optimal energy cost management while supporting the reliable electricity supply that powers modern conveniences.
Worked example
400 V, 10 A, PF 0.9 → about 6235 W (6.24 kW).
FAQ
Why √3?
It relates line and phase quantities in a balanced three-phase system.