Reference temperature

means 20oC for no-load loss, 55oC for load loss of liquid-immersed distribution transformers at 50 percent load, and 75oC for load loss of both low-voltage and medium-voltage dry-type distribution transformers, at 35 percent load and 50 percent load, respectively. It is the temperature at which the transformer losses must be determined, and to which such losses must be corrected if testing is done at a different point. (These temperatures are specified in the test method in 10 C.F.R. Appendix A to subpart K of part 431.)