PRC-027-1

PRC-027-1

Coordination of Protection Systems for Performance During Faults

PRC-027-1 requires Transmission Owners, Generator Owners and Distribution Providers to develop Protection System settings for BES Elements through a documented process, so that Protection Systems operate in the intended sequence during Faults, including exchanging proposed settings with the owners of electrically joined Facilities. It also requires a Protection System Coordination Study, or a Fault current comparison that triggers one, at least every six calendar years for Elements with the protection functions in Attachment A.

Who it applies to

Transmission Owners and Generator Owners, and Distribution Providers that own the Protection Systems below.
Facilities: Protection Systems installed to detect and isolate Faults on BES Elements.
Category 2 Generator Owners of non-BES inverter-based resources are not subject to PRC-027-1, whose Facilities are Protection Systems installed to detect and isolate Faults on BES Elements, unless a later revision of the standard includes them.

Key dates

April 1, 2021: effective date, delayed from October 1, 2020 due to COVID-19 per FERC order.
December 31, 2027: end of the first six-calendar-year interval, which starts on the April 1, 2021 effective date. The initial R2 Protection System Coordination Studies under Option 1, and the initial Fault current comparisons and any resulting studies under Option 2, must be complete no later than six calendar years after the effective date; ReliabilityFirst reads that as December 31, 2027. Entities that want margin plan to April 1, 2027.
By April 1, 2021: entities using Option 2 for the initial R2 performance had to establish an initial Fault current baseline.

What each requirement asks for, in plain English.

R1 · Settings development process

What it means. Establish a process for developing new and revised Protection System settings for BES Elements so that Protection Systems operate in the intended sequence during Faults. The process includes a review and update of short-circuit model data for the BES Elements under study and a review of the developed settings. For settings on BES Elements that electrically join Facilities owned by separate Transmission Owners, Generator Owners or Distribution Providers, it includes provisions to provide proposed settings to the other owner(s); respond to settings received by identifying coordination issues or affirming none were found; verify identified issues are addressed before implementation; and communicate revised settings that result from unforeseen circumstances during implementation or commissioning, Misoperation investigations, maintenance, or emergency replacements after Protection System component failure.

Evidence an auditor expects. Dated documentation of the established settings development process.

R2 · Periodic coordination review

What it means. For each BES Element with Protection System functions listed in Attachment A (distance 21 where infeed or zero-sequence mutual coupling is used to determine reach, instantaneous overcurrent 50, inverse time overcurrent 51, and directional overcurrent 67 in a non-communication-aided scheme, where available Fault current levels are used to develop the settings and the functions require coordination with other Protection Systems), either perform a Protection System Coordination Study at an interval not exceeding six calendar years (Option 1); or compare present Fault current values to an established baseline and perform a study when the comparison shows a 15 percent or greater deviation (three phase or phase to ground) at a bus the Element connects to, all at an interval not exceeding six calendar years (Option 2); or use a combination (Option 3). The baseline is updated each time a study is performed.

Evidence an auditor expects. Dated documentation of the Protection System Coordination Studies and/or Fault current comparisons.

R3 · Use the process

What it means. Use the R1 process to develop new and revised Protection System settings for BES Elements.

Evidence an auditor expects. Dated documentation showing the R1 settings development process was used.

For inverter-based plants

PRC-027-1 does not single out inverter-based resources; for dispersed power producing resources, footnote 1 also allows the Option 2 Fault current baseline to be set at the BES aggregation point (total capacity greater than 75 MVA).