Does the star or delta configuration affect line current?

For a balanced three-phase load with the same apparent power and line voltage, line current is identical in both star and delta configurations. The configuration affects phase current and phase voltage internally, not the line current.

What is the formula used?

Line current I (A) = S (VA) ÷ (√3 × V_L) when S is apparent power. Equivalently, I = P (W) ÷ (√3 × V_L × PF) when P is real (active) power.

What power factor should I use?

Use the rated power factor of the load. Induction motors typically run at 0.8–0.9 PF. Resistive heaters are 1.0. If unsure, 0.8 is a conservative estimate for general motor loads. A lower power factor results in higher current for the same real power.

What is the difference between apparent, real, and reactive power?

Apparent power (kVA) is the total power drawn from the supply. Real power (kW) is the portion doing useful work. Reactive power (kVAR) is the portion stored and returned by inductors/capacitors. They relate by: kVA² = kW² + kVAR².

Can I use this for single-phase calculations?

No. For single-phase systems, I = S/V when using apparent power, or I = P/(V × PF) when using active power. This tool is specifically for balanced three-phase AC systems.

Three Phase Current Calculator

Enter apparent power (kVA), line voltage, and power factor to instantly find line current for a balanced three-phase AC system.

System Parameters

Apparent Power (S)

kVA

Line-to-Line Voltage (V_L)

Power Factor (PF) (0 – 1)

Configuration

Star (Y) Delta (Δ)

For a balanced load, line current is the same in both configurations.

Line Current (I_L)

—

Enter values to calculate

Power Breakdown

Apparent Power (S) —

Real Power (P) —

Reactive Power (Q) —

Phase Details

Phase Voltage (V_ph) —

Phase Current (I_ph) —

Phase Angle (θ) —

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Summary

Enter apparent power (kVA), line voltage, and power factor to instantly find line current for a balanced three-phase AC system.

How it works

Enter apparent power (S) in kVA.
Enter line-to-line voltage in volts.
Enter the power factor (0 to 1).
Select star (Y) or delta (Δ) configuration — both give the same line current for balanced loads.
For apparent power, the calculator applies I = S / (√3 × V_L). Equivalently, using active power gives I = P / (√3 × V_L × PF).
Real power (kW) and reactive power (kVAR) are shown as additional outputs.

Use cases

Size circuit breakers and fuses for three-phase motors.
Determine cable conductor ratings for industrial installations.
Verify generator or transformer capacity for a given load.
Cross-check motor nameplate current against system calculations.
Design switchgear and distribution panels for commercial buildings.
Estimate reactive power compensation requirements.

Frequently Asked Questions

Last updated: 2026-06-13 · Reviewed by Nham Vu