The analysis of an ungrounded Wye-Delta transformer bank serving aninduction motor and single-phase lighting loads

This paper documents the detailed analysis of the three-phase ungrounded wye-delta transformer bank serving a combination three-phase induction motor and single-phase lighting load. A 3×3 transfer function matrix is developed that makes it possible to determine the load line-to-line voltages with a knowledge of the primary voltages of the transformer bank. Included in the transfer function matrix are the transformer impedances, unsymmetrical secondary impedance matrix, and the impedances of the motor and single-phase lighting load