PCB alternatives-an update transformer insulation

Existing alternatives for PCB (polychlorinated biphenyl) filled power transformers can be classified into four distinct categories: (1) mineral oil; (2) less flammable (high fire point) fluids; (3) nonflammable fluids; and (4) nonfluids (dry types). The status of commercially available PCB alternatives is updated, and a comparison of technical characteristics that are important to the user is provided. Economic comparisons are also made. The relevance of existing product standards and the development of new standards, as well as the effects of various codes, are discussed. It is concluded that each alternative has undesirable characteristics, but the product which eliminates all of these concerns (operating efficiency, first cost, flammability, size, weight, etc.) has not yet been developed, nor is it likely to be developed in the near future