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Transformer kVA to Amps Formula:
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The transformer kVA to amps calculation converts the apparent power rating of a transformer (in kVA) to the current flow (in amps) at a specific voltage. This is essential for proper transformer sizing and electrical system design.
The calculator uses the formula:
Where:
Explanation: The formula converts kVA to VA (by multiplying by 1000) then divides by voltage to get current in amperes.
Details: Accurate current calculation is crucial for selecting proper conductor sizes, circuit breakers, and other protective devices in electrical systems with transformers.
Tips: Enter the transformer kVA rating and the system voltage. Both values must be positive numbers. The calculator will output the current in amperes.
Q1: Is this calculation the same for single-phase and three-phase transformers?
A: This formula works for single-phase transformers. For three-phase transformers, an additional factor (√3 ≈ 1.732) is needed in the calculation.
Q2: Why is kVA used instead of kW for transformer ratings?
A: Transformers are rated in kVA (apparent power) rather than kW (real power) because their capacity is limited by current and voltage, not just the actual power being used.
Q3: What's the difference between primary and secondary current?
A: The current differs between primary and secondary sides based on the voltage ratio. This calculator gives current for the side whose voltage you input.
Q4: How does transformer efficiency affect this calculation?
A: The kVA rating already accounts for typical transformer losses, so efficiency isn't factored into this basic current calculation.
Q5: What safety margin should I add to the calculated current?
A: For continuous loads, the National Electrical Code typically recommends using no more than 80% of a circuit's capacity, so you might multiply the result by 1.25.