Thermal evaluation and loading of oil-immersed distribution transformers

Manufacturers must continually investigate new materials to stay competitive. Users must load transformers to their thermal limit in order to realize operating economies. The test procedures and loading guides discussed in this paper offer means by which both can affect substantial savings. Soon the proposed test procedures will receive official “IEEE Standards” designation. It is urged that all manufacturers and users support this standard, and the loading guide C57.91, so that we may work on a common basis understood and accepted by all concerned.