Transformer Calculator

Comprehensive transformer calculations including sizing, current calculations, kVA selection, and fault current analysis.

Transformer Sizing from Load

Calculate required transformer size based on load requirements with NEC continuous load multipliers.

System Type

System Voltage (V)

Continuous Load (kW)

Operates ≥3 hours continuously

Non-Continuous Load (kW)

Operates <3 hours

Power Factor

Typical: 0.80-0.90

Safety Factor (%)

For future growth

NEC 215.2(A)(1): Continuous loads must be calculated at 125% of actual load
Definition: Continuous load operates for 3 hours or more
Power Factor: Lower power factor requires larger transformer for same kW load
Safety Factor: 25-30% typical for moderate future growth
Loading: 50-80% utilization is optimal for efficiency and lifespan