Three Phase Power Calculation Guide
Why Three Phase Power Matters
Three phase power is used where loads are large, steady, or motor driven. It keeps current lower than a single phase supply for the same useful output. That means smaller conductors, smoother motor torque, and better equipment sizing. This calculator gives a worked example, so the values are easier to check before a design note is written.
Inputs Used by the Tool
The main inputs are line voltage, line current, power factor, and connection type. A balanced load uses one current value for every phase. An unbalanced example uses three current values and averages their apparent demand. The tool also accepts efficiency, operating hours, and energy price. These options help convert electrical demand into output power, daily energy, and estimated running cost.
Reading Power Values
Real power is the useful working power. It is measured in watts or kilowatts. Apparent power is the total volt ampere demand seen by the supply. Reactive power is the magnetizing part used by motors, transformers, and coils. Power factor links these values. A low power factor raises current for the same real load. This can increase losses and cable heating.
Star and Delta Checks
Star and delta connections change phase values. In a star load, phase voltage equals line voltage divided by square root three. Phase current matches line current. In a delta load, phase voltage matches line voltage. Phase current equals line current divided by square root three. The calculator shows these values for learning and checking.
Balanced Load Formula
For a balanced system, real power equals square root three times line voltage times line current times power factor. Reactive power uses the sine of the phase angle instead. Apparent power uses the same formula without power factor. These relationships match common power engineering practice for balanced three phase loads.
Practical Use
Use the example table to compare typical cases. Motors often need allowance for starting current and service factor. Heating loads may have a power factor near one. Drives can change current waveform, so measured true power may be needed. Treat results as planning values. Confirm final designs with local codes, nameplate data, protection settings, and a qualified electrical professional. Recorded results also support maintenance planning. They reveal overload risk, wasted capacity, and cost changes. Keep dated entries for audits, upgrades, and future load studies during site reviews later.