What steps are involved in a transformer oil filtration procedure?

A typical procedure includes safety isolation, setting up sealed hoses and clean filters, warming oil if required, and circulating oil through filtration and vacuum dehydration equipment. The system removes particles and water, and often degasses the oil. Operators monitor flow, temperature, and differential pressure across filters. Samples are taken before and after treatment to verify BDV, moisture, and dielectric loss improvements. The process continues until targets are met, then equipment is disconnected and ports are sealed. Final checks include oil level, leak inspection, and documentation of test results and volumes processed.