How to filter transformer oil during maintenance safely?

Safe oil filtration requires isolating the transformer if needed, grounding all equipment, using clean and dry hoses, and preventing air ingress. Oil temperature is controlled to optimize moisture removal without damaging insulation. Filtration units apply vacuum dehydration, degassing, and fine filtration. Spill containment, fire safety measures, and waste handling for filters are essential. Pre and post filtration oil testing confirms effectiveness and ensures oil quality meets service requirements.