What topics are covered in a guide to transformer oil analysis?

Guides usually cover sampling practices, contamination control, core oil tests (BDV, moisture, acidity, dielectric dissipation factor, resistivity, interfacial tension), dissolved gas analysis interpretation for thermal and electrical faults, and advanced indicators like furans for cellulose aging. They also explain trend analysis, alarm thresholds, and how results drive maintenance actions such as drying, degassing, regeneration, leak repair, or internal inspection. Many include case studies and decision trees linking gas patterns to likely fault types.