What is the procedure for how often should transformer oil be tested and what parameters are evaluated?

Transformer oil should be tested annually as part of routine maintenance, though more frequent testing may be necessary for older or critical transformers. Key parameters evaluated include dissolved gas analysis (DGA), moisture content, acidity, dielectric strength, and furan analysis. These tests help assess the oil’s condition and the transformer’s health, identifying potential issues such as insulation degradation or overheating, ensuring reliable operation and longevity of the transformer.