What should be considered when purchasing used oil filled transformers?

Used oil filled transformers require careful technical and environmental screening. Confirm nameplate ratings, voltage class, impedance, tap range, and compatibility with your system. Review test history: insulation resistance, turns ratio, winding resistance, and especially oil condition data like DGA, moisture, acidity, and BDV. Check for leaks, corrosion, bushing condition, and evidence of overheating. Determine whether the oil is PCB free and obtain documentation, because PCB presence changes legal handling and disposal obligations. Consider transport risk, dry out needs, and commissioning tests. Price should reflect remaining life and refurbishment scope.