Application of Phase Shifting Transformers for Daniel-McKnight 500kV Interconnection

Large phase-shifting transformers (PST´s) are not common in the United States, consequently, little has been published concerning these unique transformers. This paper will discuss the application, design, testing, and protection of two parallel 1000 MVA 230kV PST´s which were installed at the Plant Daniel substation of Mississippi Power Company (MPC) on the McKnight 50OkV interconnection with Gulf States Utilities (GSU). These units have been in operation since May, 1984 and have experienced no problems.