Project 2021-05 Modifications to PRC-023

​​​​​​​​​​​​​​​​​​​​​​Related Files​


Board Adopted: February 16, 2023

Filed with FERC: March 2, 2023​  

Requirement R2, in PRC-023-4, requires applicable functional entities to set their Out of Step Blocking1 (OOSB) elements to allow tripping for faults during the loading conditions prescribed by Requirement R1. A requirement to allow tripping in a Standard whose intent is to block tripping, has led to some entities disabling their PSB relays. Disabling of these relays could lead to tripping during stable power swings causing an increased reliability risk. PSB relays provide increased security by preventing relays from tripping for stable power swings. Preventing the tripping of transmission lines during these types of disturbances increases the reliability of the BES.  Requirement R2 should be removed or modified because it has been interpreted to restrict the setting of PSB elements making determination of appropriate settings more difficult and making compliance with PRC-026 more difficult.  The present inclusion of out of step tripping in Attachment A, Item 1.2 needs to be clarified.

Attachment A exclusion 2.3 should also be removed or modified. This exclusion is no longer needed and that exclusion has contributed to the confusion surrounding R2. Attachment A exclusion 2.3 has been interpreted as being in conflict with R2. Both R2 and Attachment A exclusion 2.3 are either not needed or should be modified in the Standard.

Standard(s) Affected: PRC-023-4​

Purpose/Industry Need
The purpose of the proposed project provides a reliability-related benefit by modifying or eliminating PRC-023-4 Requirement R2 to more effectively apply PSB when appropriate to improve BES reliability.  Proper application of PSB can also be helpful in complying with PRC-026.  It will modify or remove an exclusion (Attachment A – 2.3) that may no longer be needed.

The term power swing blocking (PSB) is also used by industry to describe these elements​.​ The PSB term will be used for the remainder of this SAR.​




​Consideration of Comments
​Final Draft

Clean Redline to Last Posted | Redline to Last Approved​


​Implementation Plan
Clean | Redline to Last Posted

​​Supporting Materials

Techn​ical Rationale
Clean | Redline to Last Posted​

Final Ballot

Updated Info



01/10/23 - 01/24/23

Ballot Results

Draft 1

Clean  Corrected file posted 1/12/2023 to reflect the proposed changes to the currently approved standard language​  | Redline

Implementation Plan

Supporting Materials

Unofficial Comment Form

VRF/VSL Justifications

Technical Rationale

Appendix C
Clean | Redline 

Initial Ballots and Non-binding Poll

Updated Info​



11/23/22 - 12/05/22​ (Extended to reach quorum)

Ballot Results

Consideration of Comments​

Join Ballot Pools

10/10/22 - 11/15/22

Comment Period


Submit Comments​​​

​10/10/22 - 12/05/22​ (Extended to reach quorum)

Standard Authorization Request (SAR)
Clean Redline​
The Standards Committee accepted the SAR on December 15, 2021

Drafting Team Nominations

Supporting Materials

Unofficial Nomination Form (Word)

Nomination Period


Submit Nominations

​​06/29/21 - 08/10/21

Standard Authorization Request​

Supporting Materials

Unofficial Comment Form (Word)

Comment Period


Submit Comments​

06/29/21 - 07/28/21