A Remedial Action Scheme can drop several hundred MW of generation in under a second — and if you don't know whether it's armed, your contingency analysis is wrong. RAS shows up on the NERC RC exam for two reasons: the Reliability Coordinator is the entity that reviews a RAS before it goes in service, and the RC is the one who has to operate around it in real time. Here's how the exam frames it, and where candidates lose points.
Test Tips
- Anchor on the definition, not the hardware. A RAS detects predetermined System conditions and automatically takes corrective action — tripping generation, shedding load, or reconfiguring the system. It is not the protection system that clears a fault. If the stem describes relays isolating a faulted element, that's a Protection System, not a RAS. Also know that Special Protection System (SPS) is the older term for the same thing; exam material and regional documents still use both.
- Memorize the exclusions. Automatic underfrequency load shedding (UFLS) and undervoltage load shedding (UVLS) programs applied as required by NERC standards, out-of-step tripping, autoreclosing schemes, and controllers that regulate voltage, reactive power, or DC line flow are specifically outside the RAS definition. A distractor that calls the UFLS program a RAS is wrong every time.
- The reviewing entity is the Reliability Coordinator. Under PRC-012 (Remedial Action Schemes), a RAS-entity submits a new or functionally modified RAS to the reviewing Reliability Coordinator before it is placed in service. Trap answers hand that job to the Planning Coordinator, the Transmission Owner, or the Regional Entity. Planning entities support the studies — the review sits with the RC.
- Connect RAS status to your real-time picture. This is where scenario questions live. If a RAS is disarmed or out of service, the contingency it was covering is no longer mitigated. That drives a fresh Real-time Assessment and can change an applicable SOL or IROL. Think IRO-008 (RC operational analyses and Real-time Assessments) and IRO-009 (RC actions to operate within IROLs), not just the PRC paperwork.
- Know which PRC standard does what. PRC-012 covers review and periodic evaluation of the RAS itself. PRC-016 covers analysis of RAS operations and Misoperations. PRC-017 covers RAS maintenance and testing. The exam loves three-answer clusters built out of exactly these three.
- Treat cross-border RAS as a coordination question. When a RAS affects a neighboring RC Area, the answer usually involves notifying and coordinating with the adjacent Reliability Coordinator — IRO-014 (Coordination Among Reliability Coordinators) territory. RAS status is also the kind of Real-time data an RC can require through its data specification under IRO-010, with the TOP and BA supplying it under TOP-003.
5 Practice Questions
Question 1
Which statement best describes a Remedial Action Scheme?
- A Protection System that detects and isolates faulted BES Elements
- A scheme that detects predetermined System conditions and automatically takes corrective action, such as tripping generation, shedding load, or reconfiguring the System
- An automatic underfrequency load shedding program applied to meet NERC requirements
- An autoreclosing scheme that restores a line after a temporary fault
Question 2
A Transmission Operator asks whether its automatic underfrequency load shedding program — installed to meet NERC UFLS requirements — has to be submitted to the RC as a Remedial Action Scheme. What is the correct response?
- Yes. Any scheme that automatically sheds load is a RAS.
- No. UFLS programs applied as required by NERC Reliability Standards are excluded from the RAS definition.
- Yes, but only if the program sheds more than 300 MW.
- Only during seasons when the program is armed.
Question 3
Under PRC-012, which entity performs the review of a new or functionally modified RAS before it is placed in service?
- The Planning Coordinator
- The Transmission Owner
- The reviewing Reliability Coordinator
- The Regional Entity
Question 4
Mid-shift, a RAS that arms for the loss of a key 500 kV line is reported out of service for relay work. What is the RC's most appropriate first action?
- None. RAS availability is a planning-horizon issue only.
- Direct the Transmission Operator to immediately shed firm load.
- Update the Real-time Assessment to reflect the unavailable RAS, reevaluate the applicable SOLs and IROLs, and take or direct actions as needed.
- Defer the issue to the next day-ahead study cycle.
Question 5
Following a disturbance, a RAS operated but only two of its four intended generator trips executed. Which standard governs the analysis of that RAS operation and its Misoperation?
- PRC-012
- PRC-016
- PRC-017
- PRC-006
Answer Key & Explanations
- B. The NERC Glossary defines a Remedial Action Scheme as a scheme designed to detect predetermined System conditions and automatically take corrective actions. Option A describes a Protection System operating for faults; options C and D are named exclusions from the RAS definition.
- B. UFLS and UVLS programs applied as required by NERC Reliability Standards (the UFLS program requirements live in PRC-006) are explicitly excluded from the RAS definition. Size and seasonal arming don't change that.
- C. PRC-012 (Remedial Action Schemes) places the RAS review with the reviewing Reliability Coordinator. Planning Coordinators and Transmission Planners contribute studies and data, but the review obligation is the RC's.
- C. An unavailable RAS changes the post-contingency response of the System. IRO-008 obligates the RC to perform Real-time Assessments, and IRO-009 obligates the RC to act — or direct action — to prevent or mitigate IROL exceedances. Shedding firm load first (option B) skips the assessment step.
- B. PRC-016 addresses RAS Misoperations, including the analysis and corrective action. PRC-012 is the review and evaluation of the scheme; PRC-017 is maintenance and testing; PRC-006 is UFLS.
Standards get revised. Before you rely on a citation in an audit or a procedure, confirm the current enforceable version and requirement text at nerc.com.
Keep Studying
EPG Solutions builds RC exam prep from the control room out — written by a NERC-certified Reliability Coordinator, not a curriculum vendor. If you want more reps like these, look at the GridCert RC Prep Course with AI Instructor, the NERC RC 2026 Practice Test Book with 400+ questions, and the GridCert RC Test Lab exam simulator at epgsolutions.services.