| 摘要 |
Method for replacing a coolant containing PCB in electrical induction apparatus having a tank containing the PCB-containing coolant, an electrical winding and porous solid cellulosic electrical insulation immersed in, and impregnated with, the PCB-containing coolant with a substantially PCB-free permanent coolant to convert said electrical apparatus into one in which the rate of elution of PCB into the PCB-free coolant is below the maximum allowable rate of elution into the coolant of an electrical apparatus rated as non-PCB comprising steps of: (a) draining the PCB-containing coolant from said tank; (b) filling the tank with an interim dielectric cooling liquid; (c) electrically operating the apparatus; (d) thereafter draining the interim dielectric cooling liquid containing the eluted PCB from the tank; (e) repeating the cycle of steps (b), (c) and (d) a sufficient number of times until the PCB elution rate does not exceed the rate of 50 ppm PCB based on the weight of the permanent coolant after 90 days of electrical operation; and (f) filling the tank with a substantially PCB-free permanent coolant selected from the group consisting of high boiling, high viscosity, silicone oils, synthetic ester fluids, poly-alpha-olefin oils and hydrocarbon oils.
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