How is transformer oil filtration conducted?

Transformer oil filtration is conducted to remove impurities, moisture, and gases from the oil to restore its insulating and cooling properties. The process typically involves the following steps:

Oil Sampling: Initially, an oil sample is taken to assess the condition of the oil and determine the extent of contamination.
Heating: The oil is often heated to reduce viscosity, making it easier to filter and remove moisture and gases.
Vacuum Dehydration: The oil is passed through a vacuum chamber where moisture and dissolved gases are extracted under reduced pressure.
Filtration: The heated oil is then passed through a series of fine filters to remove solid particles and contaminants.
Degassing: If necessary, the oil undergoes a degassing process where any remaining dissolved gases are removed.
Recirculation: The filtered oil is recirculated back into the transformer, ensuring it is evenly distributed and free from contaminants.
Testing: After filtration, the oil is typically tested again to ensure it meets the required standards for dielectric strength and purity before the transformer is returned to service.