Negative-sequence overcurrent element application and coordination in distribution protection

Abstract

Negative-sequence overcurrent elements do not respond to balanced load and can thus be set to operate faster and more sensitively than phase overcurrent elements for phase-to-phase faults. It is demonstrated that on a radial distribution system negative-sequence overcurrent elements need only be coordinated with downstream phase overcurrent devices for phase-to-phase faults. Coordination for other fault types is then achieved with no further analysis required. The effects of negative-sequence load current and open phase conductors on negative-sequence overcurrent elements are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>