Symmetrical sequence controls: A method for bench-testing negative sequence detective relays

Symmetrical Components is a topic which even a graduate electrical engineer, who took a course on the subject, may not completely understand. Workers who maintain protective relays may have little knowledge of Symmetrical Components. The result of this unfamiliarity may be that relays such as those which respond to negative sequence voltages are never again tested properly, or readjusted to a more desireable setting, after leaving the manufacturer. The intent of this paper is to present a method of bench-testing negative sequence detecting devices by individuals who possess little knowledge of Symmetrical Components.