Transformer Study Guide for Red Seal Electricians

Transformer study combines voltage ratio, current, kVA, phase, and equipment behaviour. Keep ideal electrical relationships separate from Code sizing decisions and troubleshooting evidence.

For an ideal transformer, voltage follows turns ratio. Three-phase line current from kVA uses I = kVA × 1000 ÷ (√3 × VLL).

• Distinguish single-phase and three-phase current formulas.
• Do not reverse primary and secondary turns ratio.
• Use kVA rather than kW when working directly from transformer nameplate rating.
• Calculated full-load current is not the complete Code sizing decision.
• Use primary, secondary, loading, tap, and connection measurements when troubleshooting.