Posting for Initial Open Process Review of PRC-006-NPCC-3 Automatic Underfrequency Load Shedding

The clean and redlined versions of the revised NPCC Regional Standard PRC-006-NPCC-3 Automatic Underfrequency Load Shedding, have been posted on the NPCC Website for a 45-day comment period through May 29, 2025, along with a proposed Implementation Plan and Technical Rationale document.

This initial draft has been developed in accordance with the NPCC Regional Standard Processes Manual (RSPM) and within the scope of a NPCC Regional Standard Authorization Request (RSAR), which was accepted by the NPCC Regional Standard Committee (RSC). The revisions are also presented as mandated by the NERC Rules of Procedure.

Among the proposed changes included in the revised draft of the Standard are:

• Revisions to footnote #1 found in Tables 1, 2, and 3 of Attachment C, related to the tolerances for both the 300ms and 10s load shedding stages.

• Clarification of the UFLS program performance characteristics in Figure 1.

• Revisions to Requirement 10 to include applicability to protective functions.

• The addition of curve data equations for Figure 2.

• Removal of the upper limit of the cumulative requirements provided in Attachment C, Tables 1, 2 and 3.

Also posted is a set of questions developed by the Regional Standard Drafting Team to solicit comments on the draft standard and the associated draft Implementation Plan for the Regional Standard and a question on the cost effectiveness of the requirements.

Comments on the posted materials may be submitted through the NPCC Forms, which may be accessed through: https://forms.office.com/r/JHtBfkNWU0.

Please contact NPCC at Contact Us with any questions regarding revisions to the Standard and the attached material.