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Oil Transformer 2026-05-15 10 min readBy Ziyao Engineering Team

Oil-Immersed Transformer Selection Guide

S11/S13/S20/S22 oil-immersed transformers: selection criteria, cooling methods, and IEC 60076 compliance.

Oil-Immersed Transformer Guide

Oil-immersed transformers use mineral oil for insulation and cooling. Common series include S11, S13, S20, and S22 with progressively lower losses.

Selection Criteria

  • S11: Standard efficiency, economical choice
  • S13: Improved core material, -20% no-load loss
  • S20: Low-loss design for utility distribution
  • S22-M: Ultra-premium, MEPS Tier 2, -40% loss

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