Hiromi Kanbe*, Masatoyo Shibuya* and Naomichi Hirayama**

* Central Research Institute of Electric Power Industry
** Chiba Institute of Technology
(2-11-1 Kita, Iwato, Komae, Tokyo 201 Japan)

Abstract

In 1989, PCB was found in recycled insulation oils used in some pole transformers in traces of 50mg 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 0.05mg per kg of insulation oil at a vacuum pressure of less than 0.05Torr; a temperature of 200*C[Celsius degeree]; and vacuum holding time of 10hrs. Overall the test was successful, with no significant negative effects on the treatment facility or the surrounding environment.

Key words: Poly chlorinated biphenyl, vacuum heating separation method, pole transformer, insulated oil, removal of PCB