how to make transformer oil?

Making transformer oil involves refining crude mineral oil to achieve high purity and specific properties. The process includes distillation to separate lighter fractions, followed by hydrotreating to remove impurities like sulfur and aromatics. Additives may be incorporated to enhance oxidation stability and improve electrical insulation properties. It’s crucial to ensure the oil meets industry standards, such as ASTM D3487, to ensure safety and efficiency in transformer applications.