Losses in transformers

It is proposed in the paper to divide transformer losses into no-load and load losses, the former including core and dielectric losses, and the latter resistance and stray losses. The magnitude of the stray loss is shown in a large number of commercial transformers and in a few experimental machines. The relation between the impedance watts and the load losses is discussed, and the conclusion reached that they are practically equal. Results of tests are given, showing the magnitude of the dielectric losses in high-voltage transformers. It is recommended that Sections 156 to 159 of the Standardization Rules be amended to define transformer losses as no-load losses, including core and dielectric losses, and load losses, including resistance and stray losses. It is further recommended that all losses be measured at the operating temperature.