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Efficiency 2026-04-22 10 min readBy Ziyao Engineering Team

Transformer Loss Calculation Guide

Calculate no-load and load losses for transformer TCO analysis. IEC 60076 loss classes explained.

Transformer Loss Calculation

Transformer losses consist of no-load (core) losses and load (copper) losses. Understanding these is essential for TCO analysis.

Loss Components

  • No-Load Loss: Constant, from core magnetization. Depends on core material and flux density.
  • Load Loss: Proportional to current squared (I²R). Includes winding loss + stray loss.
  • TCO Formula: Purchase Price + (NLL × hours × rate × years) + (LL × LF² × hours × rate × years)

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