Size a transformer from kW or Amps for Single-Phase or Three-Phase systems. Pick HT voltage (11kV / 13.8kV / 33kV), apply safety margin, and snap to standard kVA using IEC or your supplier list.
Transformer sizing is based on apparent power (kVA), not only real power (kW). Loads with lower power factor draw more current and require a larger transformer for the same kW. This tool sizes the transformer using standard electrical equations and then selects the next available standard kVA from your chosen series.
For 3-phase: Load = 500 kW, LT = 400V, PF = 0.80, Safety = 10%:
Transformer rating is in kVA. For the same kW, a lower PF increases kVA and current, so a larger transformer is needed.
Use it for future expansion, uncertain loads, motor starting additions, or when you want spare capacity. Typical range is 10–25%.
HT current and turn ratio depend on HT voltage. A 33kV system draws much lower HT current than an 11kV system at the same kVA.
It matches your supplier’s catalog and local standard ratings, so the “next standard” choice is realistic for procurement.
| Current (A) | Single-Phase kVA | Three-Phase kVA |
|---|---|---|
| 50 A | 20 kVA | 35 kVA |
| 100 A | 40 kVA | 69 kVA |
| 200 A | 80 kVA | 139 kVA |
| 300 A | 120 kVA | 208 kVA |
| 400 A | 160 kVA | 277 kVA |
| 500 A | 200 kVA | 346 kVA |
| 750 A | 300 kVA | 520 kVA |
| 1000 A | 400 kVA | 693 kVA |
| 1500 A | 600 kVA | 1039 kVA |