Bus total overcurrent system for a protective relay

摘要

A power system bus total overcurrent system is used with a part of a power system which includes two buses and first and second power line portions which extend between them. A protective relay system includes protective relays for each of the first and second power line portions, located near the two buses, wherein the relays determine the total current into and out of each bus. The bus total overcurrent system includes first and second communication lines between each pair of relays and another communication line which extends between the first and second communication lines. In a current balance arrangement, the relays measure difference current using the same communication line arrangement between the two pairs of relays to determine a fault condition. Fault determinations are made in each case by the protection algorithms from total and difference currents.