Voltage and Reactive Control (VAR-001 & VAR-002) on the NERC RC Exam: Test Tips and 5 Practice Questions

Voltage problems are local, they develop fast, and they kill more exam candidates than they should. The VAR standards split responsibility cleanly between the Transmission Operator and the Generator Operator, and the exam loves to test whether you know which entity does what. If you've worked a shift where a unit dropped its AVR to manual, you already know why this matters in the control room — low voltage in one pocket of the system can slide toward voltage collapse while frequency looks perfectly normal.

Test Tips

• Know who owns what. The Transmission Operator specifies the voltage schedule and directs voltage/reactive operations. The Generator Operator runs the machine to that schedule. Exam writers routinely swap in "Balancing Authority" or "Reliability Coordinator" as distractors — the BA balances MW and frequency, not local voltage. VAR is TOP/GOP territory.
• Memorize the default AVR state. Under VAR-002, a generator connected to the interconnected transmission system normally operates in automatic voltage control mode — AVR in service and controlling voltage — unless the Transmission Operator has instructed a different mode. "Constant power factor mode" and "constant MVAr mode" are the classic trap answers.
• Know the 30-minute notification. A status change on the AVR or power system stabilizer triggers a Generator Operator notification to the Transmission Operator within 30 minutes. Distractors will offer "immediately," "one hour," or "end of shift." Thirty minutes is the number to anchor.
• Watch for "normal conditions only." VAR-001 requires the Transmission Operator to schedule sufficient reactive resources to regulate voltage under normal and Contingency conditions. Any answer choice that limits the obligation to normal conditions is wrong.
• Understand that reactive power is local. MVArs don't travel well — reactive losses climb quickly with distance. When a question describes sagging voltage in a load pocket, the right operational answer involves reactive support near the problem area, not more MW imported from far away.
• Concepts beat version numbers. NERC revises standards periodically, and version suffixes change. The exam tests what the requirement obligates, who it applies to, and the time frames — not the revision history. Always confirm the current enforceable version at nerc.com when you study.

5 Practice Questions

Question 1

Under VAR-001, which functional entity is responsible for specifying a system voltage schedule for its area?

• A. Generator Operator
• B. Balancing Authority
• C. Transmission Operator
• D. Reliability Coordinator

Question 2

According to VAR-002, how should a Generator Operator normally operate a generator that is connected to the interconnected transmission system?

• A. In constant power factor mode
• B. In automatic voltage control mode, with the AVR in service and controlling voltage
• C. In manual excitation control
• D. In constant reactive power (MVAr) mode

Question 3

A generator's automatic voltage regulator trips out of service. Under VAR-002, within what time frame must the Generator Operator notify its Transmission Operator of the status change?

• A. Immediately, defined as within 5 minutes
• B. Within 30 minutes
• C. Within 1 hour
• D. By the end of the operating day

Question 4

Under VAR-001, a Transmission Operator must schedule sufficient reactive resources to regulate voltage levels under which conditions?

• A. Normal conditions only
• B. Contingency conditions only
• C. Normal and Contingency conditions
• D. Only during declared energy emergencies

Question 5

Voltage in a heavily loaded metropolitan load pocket is declining. Which action addresses the problem most directly?

• A. Import additional MW from a remote generating station
• B. Add or dispatch reactive support close to the low-voltage area
• C. Raise the Interconnection frequency setpoint
• D. Reduce spinning reserve requirements

Answer Key & Explanations

1. C — Transmission Operator. VAR-001 R1 places the obligation to specify a system voltage schedule on the Transmission Operator as part of its plan to operate within limits. The GOP follows the schedule; it doesn't set it.
2. B — Automatic voltage control mode. VAR-002 R1 requires the Generator Operator to operate each applicable generator with its AVR in service and controlling voltage, unless the Transmission Operator has instructed a different control mode. Power factor and MVAr modes are the distractors.
3. B — Within 30 minutes. VAR-002 R3 requires the Generator Operator to notify its Transmission Operator of a status change on the AVR or power system stabilizer within 30 minutes.
4. C — Normal and Contingency conditions. VAR-001 R2 requires the Transmission Operator to schedule sufficient reactive resources to regulate voltage under both normal and Contingency conditions. "Normal only" is the trap.
5. B — Local reactive support. Reactive power cannot be moved efficiently over long distances because reactive losses grow with distance and loading. Voltage problems are solved near the problem: capacitor banks, condensers, or generator reactive output in or near the affected area. Importing distant MW can actually worsen the voltage profile by loading the lines further.

Working toward your RC certification? EPG Solutions builds exam prep written by operators who have actually sat in the seat — practice tests, study guides, and the GridCert RC program. Browse the full lineup at epgsolutions.services.