What is the process of transformer oil filtering and when is it required?

The process of transformer oil filtering involves the removal of impurities, moisture, and gases from the insulating oil to enhance its dielectric strength and overall performance. This is typically achieved through vacuum dehydration, adsorption, or centrifugal filtration methods. Transformer oil filtering is required when the oil shows signs of contamination, such as increased moisture content or reduced insulation properties, often indicated by routine testing or after maintenance activities to ensure optimal transformer operation and longevity.