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kVA to Amps Calculator

Convert kilovolt-amperes to amperes

kVA
V
Result
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Formulas

1φI = (kVA × 1000) / V
3φI = (kVA × 1000) / (√3 × V)

Quick Reference

kVA@240V 1φ@480V 3φ
25104 A30 A
50208 A60 A
100417 A120 A
5002083 A601 A
10004167 A1203 A

Related

Amps to kVAkVA to kWTransformer Sizing

Understanding kVA to Amps Conversion

Converting kVA (kilovolt-amperes) to amps is essential when sizing electrical equipment like transformers, generators, circuit breakers, and cables. The kVA rating tells you the apparent power, while amps tells you the actual current flow.

Why Convert kVA to Amps?

Equipment like transformers and generators are rated in kVA, but you need to know the amperage to size wires, breakers, and other protective devices. The conversion depends on whether you have a single-phase or three-phase system.

Single-Phase vs Three-Phase

Single-phase systems have two wires (hot and neutral). Current is simply: I = (kVA × 1000) / V

Three-phase systems have three hot wires carrying current 120° apart. The √3 (1.732) factor accounts for this phase relationship: I = (kVA × 1000) / (√3 × V)

Practical Applications

When sizing a transformer secondary breaker, convert the kVA rating to amps at the secondary voltage. For example, a 75 kVA transformer at 208V three-phase delivers: (75 × 1000) / (1.732 × 208) = 208 amps per phase.

Frequently Asked Questions

For single-phase: Amps = (kVA × 1000) / Volts. For three-phase: Amps = (kVA × 1000) / (√3 × Volts) or (kVA × 1000) / (1.732 × Volts). Simply divide the kVA by voltage (and √3 for 3-phase) to get the current in amps.

It depends on voltage and phase. At 240V single-phase: 100,000 / 240 = 417 amps. At 480V three-phase: 100,000 / (1.732 × 480) = 120 amps per phase. At 208V three-phase: 100,000 / (1.732 × 208) = 278 amps.

kVA is a unit of apparent power in electrical systems, equal to 1000 volt-amperes. It represents the total power flowing in a circuit, including both real power (kW) and reactive power (kVAR). Transformers, generators, and UPS systems are rated in kVA.

kW (kilowatts) is real power - the power that actually does work. kVA is apparent power - total power including reactive power. They're related by: kW = kVA × Power Factor. For purely resistive loads (PF=1), they're equal. For inductive loads (motors), kVA is always higher than kW.

In three-phase systems, the three voltages are 120° apart. When calculating total power from line voltage and line current, the √3 (1.732) factor accounts for this phase relationship. It's derived from the vector sum of the three phase voltages.

Convert transformer kVA to amps at the secondary voltage, then size the breaker per NEC requirements. Primary breaker is typically 125% of primary FLA. Secondary breaker depends on application but often 100-125% of secondary FLA.

For wye (star) connections, line current equals phase current. For delta connections, line current is √3 times phase current. This calculator gives line current, which is what you need for sizing wires and breakers.

At 240V single-phase: 208 amps. At 208V three-phase: 139 amps. At 480V three-phase: 60 amps. Remember that continuous loading should not exceed 80% of these values for transformer longevity.