Graphical Presentation on Operation Principle of Protective Relay According to Winding Type and Vector Group in Transformer

전력용 변압기에서 권선방식과 벡터그룹에 따른 보호계전기 동작원리의 그래픽 표현

Protective relay for transformer operates in general by comparing with the differential current and the restraint current. These kinds of currents are changed on magnitude and phasor during the fault according to winding type and vector group. This paper presents the differential and restraint currents and operational principle of differential protective relay for two-winding and three-winding transformer with graphical model. It is developed using MATLAB for an educational purpose on engineer related in power system and protection in university and power utility including large factory.