kVA to Amps Calculator (Single & 3-Phase)
Substation transformer secondary breaker sizing, generator feeder cable selection. Calculates rated full-load current output for single-phase and 3-phase transformers, generators, and distribution switchgear.
Step-by-Step Derivation ▼ Show Steps
Calculations adhere to standard electrical engineering physics and National Electrical Code (NFPA 70) regulations.
Engineering Principles & Calculations
This calculator uses the exact mathematical relationships between Apparent Power (kVA), Voltage (V), Phase Type (1-Phase / 3-Phase Line-to-Line) to determine Rated Current (Amperes / A). In practical installations, factors such as ambient raceway temperature, harmonic distortion, duty cycle continuous operation, and conductor impedance must be accounted for by a certified electrician.
Calculates rated full-load current output for single-phase and 3-phase transformers, generators, and distribution switchgear.
Typical Application & Industry Guidelines
Substation transformer secondary breaker sizing, generator feeder cable selection.
kVA to Amps Calculator (Single & 3-Phase) Benchmark Lookup Table
| Standard 3-Phase kVA | Amps @ 208V | Amps @ 240V | Amps @ 480V |
|---|---|---|---|
| 15 kVA | 41.6 A | 36.1 A | 18.0 A |
| 30 kVA | 83.3 A | 72.2 A | 36.1 A |
| 45 kVA | 124.9 A | 108.3 A | 54.1 A |
| 75 kVA | 208.2 A | 180.4 A | 90.2 A |
| 112.5 kVA | 312.3 A | 270.6 A | 135.3 A |
| 150 kVA | 416.4 A | 360.8 A | 180.4 A |
| 300 kVA | 832.7 A | 721.7 A | 360.8 A |