Voltage & Reactive Power Control (VAR-002) on the NERC RC Exam: Test Tips and 5 Practice Questions

Voltage problems are local, fast, and unforgiving. A voltage collapse does not give you the hour you get on a thermal overload. The exam tests whether you know who controls voltage, who must tell whom, and what an operator does first when voltage sags after a contingency.

Test Tips

1. Voltage is a local problem. The Transmission Operator (TOP) owns voltage control in its area. The RC sees the wide-area picture and coordinates, but expect the TOP to be the first-line answer on schedule and setpoint questions.
2. Know the GOP's baseline duty. Under VAR-002, Generator Operators run generators in automatic voltage regulator (AVR) mode unless the TOP instructs otherwise, and they maintain the voltage or reactive schedule the TOP gives them.
3. Remember the 30-minute notification. VAR-002 requires the GOP to notify the TOP within 30 minutes when AVR status changes. Distractors will offer 15 or 60 minutes.
4. Dynamic beats static. Generators, SVCs, and synchronous condensers respond automatically during a disturbance. Capacitor banks are static and step-switched. If the question says the system must ride through the first seconds, think dynamic reserves.
5. Order of operations on low voltage. Add reactive support first (capacitors in, generator VARs up), then reduce transfers, and shed load last. Load shed is the last resort, not the first move.
6. Reactive power does not travel. It cannot be moved long distances efficiently. If an answer relies on a distant resource fixing a local voltage problem, it is probably a distractor.

5 Practice Questions

Question 1

Under VAR-002, unless instructed otherwise, how must a Generator Operator run a generator connected to the transmission system?

1. In manual excitation control
2. In automatic voltage regulator (AVR) mode
3. At unity power factor only
4. At the generator's minimum reactive output

Question 2

A generator's AVR goes out of service. Within what time must the GOP notify the TOP under VAR-002?

1. 15 minutes
2. 30 minutes
3. 60 minutes
4. At the end of the operating shift

Question 3

Who provides the voltage or reactive power schedule that a Generator Operator is expected to maintain?

1. The Transmission Operator
2. The Planning Coordinator
3. The Resource Planner
4. The Regional Entity

Question 4

Following a contingency, voltages in a load pocket are falling toward a collapse. Which action is the best first response?

1. Shed load in the pocket immediately
2. Switch in shunt capacitors and maximize reactive output from nearby generators
3. Increase transfers into the pocket
4. Wait for voltage to recover on its own

Question 5

Which resource gives the most dependable reactive response during the first seconds after a disturbance?

1. A switched shunt capacitor bank awaiting operator action
2. A distant generator with no AVR
3. A generator or SVC operating in automatic voltage control
4. A reactor taken out of service

Answer Key & Explanations

1. B. VAR-002 expects generators to operate in AVR mode unless the TOP directs a different control mode.
2. B. VAR-002 sets a 30-minute window to notify the TOP of an AVR status change.
3. A. The TOP directs the voltage or reactive schedule the GOP must maintain under VAR-002.
4. B. Reactive support goes first. Load shed is a last resort, and increasing transfers makes the voltage problem worse.
5. C. Automatic voltage control responds on its own and in real time. Switched capacitors wait on an operator or a control action, and a reactor absorbs reactive power instead of supplying it.

Verify before you test: always confirm the current effective version of VAR-002 at nerc.com.

Want the full RC question bank? EPG Solutions has RC exam prep resources built by working Reliability Coordinators. Visit the EPG Solutions store for the practice test book and study materials.