Is the oil in a filled transformer containing PCB?

The oil in a filled transformer containing PCB refers to the presence of polychlorinated biphenyls, which were commonly used as dielectric fluids in electrical equipment. However, due to their environmental and health hazards, the use of PCB-containing oil in transformers has been banned in many countries. Modern transformers typically utilize mineral oil or ester-based fluids that do not contain PCB, ensuring safer operation and compliance with regulations.