System protection and control task force's initial recommendations concerning NERC recommendation 8A loadability requirements on transmission protective relaying systems

This paper discusses with system protection and control task force's initial recommendations concerning with NERC recommendation 8A loadability requirements on transmission protective relaying systems. The NERC investigation team recommends that the zone 3 relay, if used, should not operate at or below 150% of the emergency ampere rating of a line, assuming a .85 per unit voltage and a line phase angle of 30 degrees. The planning committee shall review such exceptions to ensure they do not increase the risk of widening a cascading failure of the power system.