Abstract
In 1989, PCB was found in recycled insulation oils used in some pole transformers in traces of 50. mg per kg of insulation oil, which promoted the quick establishment of a safe separation method. One prospective method for removing such recycled insulation oils, etc. when attached and impregnated to the transformer coils was a vacuum heating separation method which heats and vaporizes PCBs under vacuum conditions. The applicability of such a vacuum heating separation method was tested with real used transformers. The test confirmed that the residual PCB on the coils could be reduced to less than 0.05 mg per kg of insulation oil at a vacuum pressure of less than 0.05 Torr ; a temperature of 200°C; and vacuum holding time of 10 hrs.
Overall the test was successful, with no significant negative effects on the treatment facility or the surrounding environment.
