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Transformer 4 uses Updated August 10, 2026

Three-Phase Transformer Calculator

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I Want to Calculate
Volt
V
Kilovolt-amps
kVA
Amps
A

This three phase transformer calculator relates kVA, line voltage, and line current. Enter any two values above to solve for the third.

Formulas

S (VA) = √3 × VL × IL
IL = (kVA × 1000) ÷ (√3 × VL)

Example

30 kVA at 400 V: line current = 30,000 ÷ (√3 × 400) = 43.3 A.

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Frequently Asked Questions

How do I calculate three-phase transformer current?

Divide the kVA times 1000 by the square root of 3 times the line voltage. For 30 kVA at 400 V, that is about 43.3 amps.

What is the three-phase power formula?

Apparent power equals the square root of 3 times line voltage times line current (S = 1.732 x VL x IL).

Why the square root of 3?

It accounts for the 120-degree phase difference between the three line voltages in a balanced system.

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