FERC Approves Proposed PRC-026-1 (Relay Performance During Stable Power Swings) Without Modification

On March 17, 2016, FERC issued a final rule accepting NERC’s proposed Reliability Standard PRC-026-1 without modification.  FERC found that NERC’s proposed standard was an “equally effective and efficient alternative” to the Commission’s directive in Order 733 (approving PRC-023-1), which had initially directed NERC to develop a new Reliability Standard to require the use of protective relay systems that can differentiate between faults and stable power swings and, when necessary, the retirement of protective relay systems that cannot meet this requirement.  NERC’s proposed standard addresses undesirable relay operations due to stable power swings, but does not prohibit relays that cannot differentiate between faults and stable power swings due to what NERC characterized as potential “unintended negative outcomes.” 

The proposed standard is applicable to “any protective function which could trip instantaneously or with a time delay of less than 15 cycles on load current (i.e., “load-responsive”)”.   FERC’s NOPR initially expressed concern over potential gaps regarding the exclusion of load responsive relays with a time delay of 15 cycles or greater, but FERC was ultimately persuaded by commenters that these relays are addressed by other Reliability Standards and that increasing the applicability to include them would impose a significant burden.

To view the final rule, click here.