Round-Robin Testing of Three Phase Padmount Transformers

This paper addresses the accuracy of 3-phase transformer loss testing with particular attention to the reliability of manufacturers´ certified loss test results. Seven three-phase padmounts, one from each of seven different manufacturers, were used in a round-robin test program. In addition to their original production tests, each of the seven manufacturers performed loss tests on the entire group of transformers. The results of the program indicate an uncomfortably wide range of results.