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1. (WO2001001537) GROUND DISTANCE RELAY FOR AC POWER TRANSMISSION LINE PROTECTION

Pub. No.:    WO/2001/001537    International Application No.:    PCT/US2000/018073
Publication Date: Fri Jan 05 00:59:59 CET 2001 International Filing Date: Sat Jul 01 01:59:59 CEST 2000
IPC: H02H 3/40
Applicants: GENERAL ELECTRIC COMPANY
Inventors: ALEXANDER, George, E.
Title: GROUND DISTANCE RELAY FOR AC POWER TRANSMISSION LINE PROTECTION
Abstract:
An improved reactance characteristic for an overall ground distance quadrilateral characteristic embodies a particular phase selector, possibly among a plurality of phase selectors and variables, that eliminates undesirable generation of a tripping signal other than only for a selected phase to ground fault. This phase selector is I1FZ1, where Z1 is the positive sequence replica impedance and I1F is the fault component of the positive sequence current component, referenced to the proper phase. Preferably, the pre-fault load current is removed from this quantity. Additionally, an improved restricted phase directional function is implemented, further improving the overall performance of the quadrilateral characteristic relay.