What must a transformer oil be free from?

A transformer oil must be free from impurities such as water, particulate matter, and dissolved gases. These contaminants can significantly affect the performance and longevity of power transformers. Water can lead to hydrolysis and corrosion, while particulate matter can cause electrical breakdowns. Dissolved gases can indicate insulation failure and compromise the dielectric strength of the transformer oil, ultimately impacting the reliability of the power transformer.