Calculate required KVA from load data, or find primary/secondary currents from a known KVA rating. Always select the next standard size up from calculated KVA.
Full load amps on secondary side
0.80–0.95 typical for motor loads
Apply if not all loads run simultaneously
Typical: 20–25% for new installations
Standard Transformer KVA Ratings
Always select the next standard size above your calculated requirement. Apply demand and diversity factors where appropriate. Add 20–25% for future load growth on new installations per good engineering practice.
KVA Rating
1Φ Primary A @ 480V
1Φ Secondary A @ 240V
3Φ Primary A @ 480V
3Φ Secondary A @ 208V
Typical Application
Transformer Formulas
KVA Calculations
Single Phase: kVA = (V × I) / 1000 Three Phase: kVA = (V × I × √3) / 1000 = (V × I × 1.7321) / 1000