Considerations in modeling and applications of three winding transformers in industrial and commercial facilities

Usage of 3-winding transformers is extended to industrial and in-plant generation in order to realize cost and real estate savings. Such an extension has been successful in most cases. However in some cases, better understanding of how to size, specify test requirements, and model the 3-winding transformers for power system studies, would have avoided unnecessary electrical distribution system sub-performance. As equipment with inherit systems the subject transformers performed as intended. The successes and short comings are attributed to the interpretations of the 3-winding transformer parameters as part of the larger industrial power system. Hence, it is essential to scrutinize the modeling, selection of case studies, scenarios, analysis of study results and system design when 3-winding transformers are used. From application experiences this paper addresses concerns associated with the selection of 3-winding transformers discusses power system sensitivity to their parameters and presents the scenarios, cases and modeling accuracies required for associated industrial system studies.