Abstract
In 1989, PCB was found in recycled insulation oils used in some pole transformers in trace of 50 mg per one kg of insulation oil, , prompting quick establishment of their safe separation method. One of prospective methods for removing such recycled insulation oils, ets. as attached and impregnated to the transformer coils may be a vacuum heating separation method which heats and vaporizes PCB under vacuum condition for separation. A proving test for applicability of the specific vacuum heating separation method was carried out with actually used transformers, which confirmed that residual PCB on coils was minimized less than a quantitative determination lower limit of 0.05 mg per one kg of insulation oil under the following standard applicable condition : vacuum of lower than 0.05 Torr ; heating temperature of 200°C; and vacuum holding time of 10 hrs., thus successfully proving insignificant effect of the treatment facility and the method on environment.
