How does transformer oil filtration equipment remove moisture and contaminants?

Filtration equipment removes particles using staged filters (coarse then fine) and removes moisture using vacuum dehydration, heating, and sometimes coalescing water separators. Under vacuum, dissolved and free water is pulled out of the oil, and degassing removes air and fault gases that can reduce dielectric performance. Some systems add adsorption media to reduce acidity and polar oxidation byproducts. Proper flow control, temperature management, and filter maintenance are essential, and results are verified by BDV and moisture ppm testing.