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Generator current calculator

Convert a generator rating in kVA or kW to full-load line current for single-phase or balanced three-phase output.

Enter the project values

All values remain in your browser. Review the assumptions before using the result.

Use line-to-line voltage for three-phase.
Your result will appear here.Calculate to see the outputs, formula and substituted working.

How the calculation works

Nameplate rating converted to steady-state line current.

Formula

I = S ÷ (√3 × VLL) or I = P ÷ (√3 × VLL × PF)

Worked example

Basis250 kVA
ArrangementThree-phase
Voltage400 V
Expected current360.84 A

Assumptions and limitations

Assumptions

  • The generator is operating at rated steady-state output.
  • Three-phase output is balanced.

What this does not check

  • Does not assess motor starting, step loads, transient voltage dip, harmonics or derating.
  • Does not select a generator or protective devices.
Formula version: 1.0 · Last reviewed: 16 August 2026

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Engineering basis: first-principles electrical relationships using user-entered values. The page does not reproduce BS 7671 tables or establish compliance. Complete the project-specific design against the current BS 7671 information, manufacturer data and the applicable project requirements.
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