Reference
kVA and amps calculator
Convert between apparent power, real power and rated current, for single phase and three phase systems.
Three phase: current equals apparent power divided by the product of the square root of three and the line voltage.
The relationship
For a three phase system the rated current is the apparent power divided by the product of the square root of three and the line voltage. For a single phase system the square root of three drops out and the current is the apparent power divided by the voltage.
Real power in kilowatts and apparent power in kilovolt amperes differ by the power factor. A transformer is rated for apparent power, so a load quoted in kilowatts has to be divided by its power factor before it can be compared with a rating.
Standard ratings and rated current
| Rating | Full load current at 400 V | Full load current at 433 V |
|---|---|---|
| 100 kVA | 144 A | 133 A |
| 160 kVA | 231 A | 213 A |
| 250 kVA | 361 A | 333 A |
| 400 kVA | 577 A | 533 A |
| 630 kVA | 909 A | 840 A |
| 1000 kVA | 1443 A | 1333 A |
| 1600 kVA | 2309 A | 2133 A |
| 2500 kVA | 3608 A | 3333 A |
Rated current at 400 V, three phase. Each rating opens its own page with currents at other voltages.
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- Cite as
Daverlan Power Systems (2026). kVA and amps calculator. https://daverlan.com/technical-resources/kva-calculator/
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