Why not Wye-Wye Transformers?

In 2013 a campus consisting of 14 buildings and associated wye-wye transformers ranging from 500 to 1000 kVA, experienced in the first five years, five transformer failures with one transformer failing twice. The campus is constantly expanding. The discussion of the investigation into the failures began with the types of engineering design firms, the types of distribution systems, but also the various transformations available, and analysis of the service entrance equipment. The campus distribution system was analyzed, comparisons made with other types of distribution systems along with the system protection, including the individual transformers’ protection. The types of system grounding of the various secondary low-voltage grounding configurations were analyzed and are documented in the paper. The actions taken over the past five years to decrease and eliminate infant mortality of transformers are documented and the results presented. The paper also discusses Williamson College of the Trades’ construction of an independent Energy Island and the interconnection with the local utility involving wye-wye transformation.