Open-delta transformer banks — Analysis of circuit

WHEN a three-phase transformer bank is operated in open delta, an unbalanced secondary voltage results, and the transformers themselves may be overloaded. The unbalanced voltage will cause a circulating current to flow which may cause overheating of the equipment in the secondary circuit to an extent depending upon the amount of the voltage unbalance and the load being carried. Wolf and Mattison¹ have described a method of overcoming the voltage unbalance, and this paper is written to mention briefly the effect of unbalanced voltages on the operation of induction motors and to present an analysis of the circuit, together with some correlated material.