What steps are involved in the transformer oil dehydration process?

Dehydration usually involves warming the oil, filtering it, and applying vacuum processing to remove water and dissolved gases. Oil is circulated from the transformer through a treatment unit where heaters reduce viscosity and help release dissolved moisture. In a vacuum chamber, moisture and gases vaporize at lower temperatures and are removed by vacuum pumps and condensers. Fine filtration removes particles. The process continues until moisture ppm and BDV reach target values, then the transformer is returned to service with confirmed insulation performance.