kVA to Amps Calculator: engineer's guide
kVA is apparent power. Amps is current. The conversion depends on system voltage and whether the system is single-phase or three-phase.
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What this calculator does
The calculator applies the standard conversion formulas and reports full-load current for the entered kVA and voltage.
Formulas used
- Three-phase:
I = S × 1000 / (√3 × VLL) - Single-phase:
I = S × 1000 / V
Variables
- S = apparent power, kVA
- VLL = line-to-line voltage for three-phase, V
- V = line-to-neutral voltage for single-phase, V
Worked example
Scenario: 1600 kVA transformer at 415 V three-phase secondary.
- I = 1600 × 1000 / (√3 × 415)
- I ≈ 2226 A
- Select main circuit breaker ≥ 2500 A frame with adjustable trip set at 2226 A + spare margin
Common mistakes to avoid
- Using line-to-neutral voltage in the three-phase formula
- Forgetting the √3 factor
- Confusing kVA (apparent) with kW (active)
Frequently asked questions
Do I use kVA or kW?
Use kVA for cable, breaker, and transformer sizing. kW is the active-power component; kVA includes reactive.
Common voltages?
415 V three-phase and 230 V single-phase in the GCC/UK/EU. 480 V three-phase and 120 V single-phase in the US.
Standards and references
IEC 60038 standard voltages
Related tools on this site
Open the calculator that pairs with this guide: kVA to Amps Calculator.
Verification note
This guide is planning support only. Final design must be verified against the applicable project specification, authority requirements, manufacturer data, and the standards cited above. Consult a licensed engineer for construction-issue calculations.