Apparent impedance seen at generator terminal for faults on HV side of Delta-Star generator transformer

Abstract

Delta-Star transformer configuration is commonly used in power systems for voltage transformation. When distance relays are used to detect faults through these Delta-Star transformers, the measurement of apparent impedance seen from delta side is more complicated than that seen on the star side. However, this can be analyzed using sequence components and networks in a systematic way. The results so achieved can be used to set protective relays and analyze their behavior and would be a good source of reference for engineers studying and practicing power systems.