Formula (Three-phase): kVA = (√3 × V × I) / 1000
Formula (Single-phase): kVA = (V × I) / 1000
- Transformer rating is expressed in kVA (kilovolt-amperes)
- Power factor affects apparent power (kVA) vs real power (kW)
- Efficiency accounts for transformer losses (copper + iron)
- Always include safety margin for future expansion (10-30%)
- Consider ambient temperature derating for installation
⚠️ Important Disclaimer:
This tool provides educational estimates only. Always consult with a licensed electrical engineer and comply with local electrical codes (IEC, NEC, etc.) before any installation. Actual sizing requires detailed load analysis, harmonics study, and protective device coordination.