What are the standard steps in a power transformer oil filtration procedure?

A typical procedure includes isolating the work area and confirming safety permits, testing baseline oil condition, connecting clean hoses with proper grounding, circulating oil through coarse and fine filters, applying vacuum dehydration and degassing as needed, monitoring flow and temperature to prevent foaming, and keeping the system sealed to avoid air ingress. After processing, samples are taken for BDV, moisture, DDF, acidity, and sometimes DGA checks. The procedure ends with leak checks, proper valve restoration, and documentation of results and volumes processed.