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NERC Exam Prep: Balancing, Interchange, and
Transmission Questions 2025/2026, Exams of
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b. NERC Operating Committee - ANSWERS -What group can
approve a change in the Disturbance Recovery Period for an Interconnection? a. NERC Interconnection Working Group b. NERC Operating Committee c. NERC Regional Council d. NERC Disturbance Analysis Working Group
c. Check targets and equipment - ANSWERS -What is the first
thing an operator should do after a relay operation? a. Check power system stabilizers b. Notify adjacent Transmission and Balancing areas c. Check targets and equipment d. Notify their PSE that the transmission path is out of service
c. Tie Lines - ANSWERS -For the ACE equation to work properly,
dynamic schedules, pseudo ties, frequency calculations, and all ________ must be metered. a. Communications b. Transformers c. Tie Lines
d. Generation
c. Energy Emergency Alert Level I - ANSWERS -What Energy
Alert Level would the following example be categorized as? "A Balancing Authority, Reserve Sharing Group, or Load Serving Entity foresees, or is experiencing conditions where all available resources are committed to meet firm load, firm transactions, etc, and requests an Energy Emergency Alert." a. Energy Emergency Alert Level IV b. Energy Emergency Alert Level III c. Energy Emergency Alert Level I d. Energy Emergency Alert Level II b. Implement the appropriate congestion management procedure.
- ANSWERS -You are a Reliability Coordinator in the Eastern Interconnection. A flow gate has become overloaded because a parallel 345kV line has relayed out and part of that load has transferred over to the flow gate causing an SOL and possible IROL violation. What would you do to relieve this violation? a. Notify another Reliability Coordinator and ask them if they are having any problem, and what should you do. b. Implement the appropriate congestion management procedure. c. Issue a Transmission warning to the Transmission Operators that lost the 345kV line. d. Place the line back in service within 30 minutes.
a. That all involved reliability entities determined that there is no reliability problems with the Arranged Interchange. b. The Department of Energy (DOE) made an in-depth study of the Interchange Agreement and determined that it would have an adverse affect on the Interconnection. c. There are available resources to meet the load. d. All parties involved realized that they would not lose money for their company with this Interchange Agreement.
b. He violated NERC standards - ANSWERS -Early in the
afternoon, a system operator notices that frequency has dropped to 59.95Hz and his balancing area's ACE is 0. In order to correct the under frequency condition, the operator pulses his generators to increase generation. Which statement best describes his actions? a. He followed NERC guidelines b. He violated NERC standards c. He helped the system d. He has not impacted the system
d. 81 MVars - ANSWERS -Voltage of a 345kV transmission line is
at 90% of normal. If you energize a capacitor rated at 100MVar, what will the actual MVars gained? a. 60 MVars b. 30 MVars c. 50 MVars d. 81 MVars
b. No further system operating action is required. - ANSWERS -A
Balancing Area's pre-contingency ACE is -40 MW (below the zero balance point). At 1525, event time ZERO, the BA looses 800 MW of generation; initial governor action arrests frequency decay and shows the BA's ACE is now -825 MW. At 1542 the BA's ACE has returned to -42 MW and the system frequency is 60.001Hz. Assuming that this event is within the DCS reporting criteria, what other action is the BA required to take? a.BA must notify the RC that Energy Emergency Alert is required to return ACE to ZERO. b. No further system operating action is required. c. The BA recovered more than 80% of its most severe single largest contingency within 15 minutes. No EEA is required. d. The BA must notify the RC that a unit has been lost and EEA Level 1 is required.
b. Ground Fault - ANSWERS -A tree has been growing under a
230kV transmission line getting closer every year. As a result of the heavy transfer of megawatts on this particular day, the line sags too close and flashes over to the tree causing the transmission line to relay out. What type of fault would this fault be classified as? a. Overvoltage Fault b. Ground Fault c. Differential Fault d. Positive Sequence Fault
a. No tag is needed because the emergency transaction has duration less than 60 minutes. b. The PSE must provide a tag for the emergency energy within 60 minutes c. The Sink Balancing Authority must provide a tag for the emergency energy within 60 minutes d. The Source Balancing Authority for the emergency energy must provide a tag within 60 minutes a. Notify the RC that this BA is in an EEA Level 2; start all available generation; schedule interchange purchases; prepare to reduce
firm load. - ANSWERS -A Balancing Authority Area has a load
forecast for 5,000 MWs for today's peak at 1430. The Interchange Schedule shows 1,500 MWs of imports for HE 0400 through HE 2200; the largest single transaction is 1,200 MWs. The total generation on line is 7,500 MWs. The largest single generator in the area is an 800 MW coal unit. At 1215 a thunder storm trips 3,000 MWs of generation with a minimum resynchronizing time of 3 hours. And simultaneously trips 1,500 MW of generation in the area exporting 1,200 MWs to this BA. The exporting BA instantly cuts the schedule to ZERO. This BA is NOT part of a Reserve Sharing Group. What action must this BA take? a. Notify the RC that this BA is in an EEA Level 2; start all available generation; schedule interchange purchases; prepare to reduce firm load. b. Notify the RC that this BA is in EEA Level 1; notify all power plants to be on alert; purchase emergency power. c. Notify the RC that this BA is in EEA Level 3; notify Transmission Operator and all Load Serving Entities that Load Shed is eminent.
d. Notify the RC that this BA is contacting TOPs and LSEs to shed 200 MW of load.
a. Differential Relay - ANSWERS -A substation maintenance
employee calls the control room and says that the west bus at one of your substations has relayed with a target 87 showing on the bus relay panel. What type of relay has operated? a. Differential Relay b. Distance Relay c. Time Overcurrent Relay d. Lockout Relay
d. Dynamic - ANSWERS -Examples of __________ reactive
resources include generators, synchronous condensers, SVC's and lightly loaded transmission lines. a. Costly b. Static c. Stationary d. Dynamic
d. 1% - ANSWERS -NERC has established minimum bias setting
standards for Balancing Authorities. The bias setting for Balancing Authorities serving native load must be at least what percent of the Balancing Authorities' estimated yearly peak demand per 0.1Hz change in frequency? a. 10% b. 5%
a and d only - ANSWERS -According to NERC, by the end of the
business day following the actual operation, two adjacent Balancing Authorities must agree upon what values with regard to inadvertent interchange? a. The hourly values of Net Interchange Schedule b. The hourly values of each Interchange Transaction c. The hourly megawatt-hour values of individual interconnecting tie lines d. The hourly megawatt-hour values of Net Actual Interchange
c. Shed load at the end of the line - ANSWERS -A radial
transmission line feeding a load is overloaded. The transmission operator must do which of the following to unload the line? a. Lower interchange schedules b. Raise interchange schedules c. Shed load at the end of the line d. Notify BA to adjust AGC
c. Current Transformers - ANSWERS -Protective relays such as
Transmission Line relays and Transformer Differential relays have current flowing to them that is proportional to the current that is in the primary circuit. In most cases, what is used to transform the current from the primary circuit to a similar proportional amount that flows to the protective relay? a. Vacuum Interrupters b. Positive Sequence Instruments c. Current Transformers
d. Series Capacitors d. The Transmission Operator for the area the generator is
located. - ANSWERS -As a Generator Operator, you realize that
your generator voltage is swinging wildly. You place your generator voltage regulator on manual, and adjust the voltage and reactive levels on the generator. Who do you contact and inform about the status of your generator voltage regulator? a. The Balancing Authority b. Power Marketers c. The Reliability Coordinator d. The Transmission Operator for the area the generator is located.
d. Prepare for the next contingency - ANSWERS -A Transmission
Operator experiences loss of a 230kV transmission line on a permanent fault. It will be out of service for two hours. In addition to making proper notifications, the Transmission Operator should take which of the following actions? a. Do nothing. In two hours, the system will be back to normal. b. None of the choices provided are correct. c. Issue an urgent public appeal for energy conservation d. Prepare for the next contingency
b. Misoperation - ANSWERS -"Any failure of a Protection System
element to operate within the specified time when an abnormal condition occurs within a zone of protection". This definition is more closely related to which of the following term?
b. 180 c. 90 d. 20
c. Angle stability limitations - ANSWERS -A power system with
long transmission lines that connect remote generation to load centers is more likely to have SOLs or IROLs determined by: a. Transmission thermal limitations b. Generator thermal limitations c. Angle stability limitations d. Generator voltage limitations
d. Voltage decreased and the current increased - ANSWERS -A
storm blows A phase and B phase conductors of a 138kV transmission line together, creating a phase to phase fault. The magnitude of the current and voltage changed instantly allowing the line distance relays at each end of the line to operate. How did the current and voltage on that line change providing the input for the relay to indicate a fault on the line? a. Voltage decreased and the current decreased b. Voltage increased and the current decreased c. Voltage increased and the current increased d. Voltage decreased and the current increased a. The PSE should provide an updated tag for the next available
scheduling hour and future hours. - ANSWERS -When a dynamic
interchange schedule of 150 MW finishes the hour with an
integrated value of 180 MWH, which of the following should occur? a. The PSE should provide an updated tag for the next available scheduling hour and future hours. b. The PSE should update the tag for future hours, but leave the next scheduling hour alone.
c. None of these ANSWERS are correct
d. No action is necessary because the deviation was not large enough for a schedule of less than 250 MW.
c. Reliability Coordinator - ANSWERS -After an EEA has been
declared, it is the responsibility of the __________ to mitigate the emergency condition? a. Transmission Owner b. Balancing Authority c. Reliability Coordinator d. Transmission Operator
c. Important - ANSWERS -Monitoring equipment must notify
operating personnel of ______________ deviations in operating conditions. a. Constant b. All c. Important d. Consistent
d. Contact the Regional Reliability Organization
b. 90 degrees - ANSWERS -Transient instability occurs when a
disturbance such as a fault on the system causes power angle excursions greater than ______ that makes the system unstable. a. 120 degrees b. 90 degrees c. 10 degrees d. 180 degrees b. The reactive requirements will change; the operator must
respond accordingly - ANSWERS -A Transmission Operator
should remember that if the system can support voltage now, as system load increases, _________________ and _____________________. a. All capacitor banks should be removed from service; generator should be operating a maximum reactive output. b. The reactive requirements will change; the operator must respond accordingly. c. The reactive requirements will change very little; no further action will be necessary d. Tap changing transformers should be turned to manual; capacitor banks should be removed from service. d. To ensure that, over the long term, Balancing Authority Areas do not excessively depend on other Balancing Authority Areas for
meeting their demand or Interchange obligations. - ANSWERS -
For what reason is NERC concerned with balancing Inadvertent Interchange among the Balancing Authorities? a. To provide a benefit to those organizations that take on the responsibility of operating a Balancing Authority. b. So that larger energy providers can demonstrate the profitability of owning and operating generation and transmission facilities. c. To maintain adequate reliability of energy transactions across each Interconnection. d. To ensure that, over the long term, Balancing Authority Areas do not excessively depend on other Balancing Authority Areas for meeting their demand or Interchange obligations. a. The ACE will be a positive value and AGC will lower generation -
ANSWERS -If the frequency bias setting is a lower value than
the frequency response of a Balancing Authority and a frequency decline is caused by a sudden loss of generation in an external balancing area, what will be the result? a. The ACE will be a positive value and AGC will lower generation b. This will not affect the ACE c. The ACE will be a negative value and AGC will increase generation d. The ACE will be zero and will take no AGC action
c. Suspend AGC and investigate - ANSWERS -Interconnection
frequency is 59.80Hz. Your ACE is a large negative value and your AGC is pulsing your units down. What should you do? a. Place AGC in flat tie line control
b. During projected light loading c. When all other reactive sources in that area are scheduled for an outage d. During winter peak loading b. Enable all governors to share in frequency regulation, and ensure the bulk system does not enter into power oscillations. -
ANSWERS -What does governor droop accomplish?
a. A decrease in generator shaft speed and in increase in generator's MW output. b. Enable all governors to share in frequency regulation, and ensure the bulk system does not enter into power oscillations. c. A graphical method of representing the performance of a governor. d. The demand at a given instant of time and the demand averaged over an hour.
d. 2 - ANSWERS -Load increases or decreased according to the
increase or decrease in frequency. For every 1% change in frequency, load will change approximately _______% in the same direction? a. 1 b. 5 c. 3 d. 2
a. Arrest Frequency Variations - ANSWERS -Governor droop is
used to: a. Arrest Frequency Variations b. Restore Frequency to normal c. Represent energy lost due to inefficiencies in generation a. By averaging the frequency response for several disturbances
during on-peak hours - ANSWERS -A Balancing Authority has
determined it will use fixed Frequency Bias. How should it determine the value to use? a. By averaging the frequency response for several disturbances during on-peak hours b. By averaging the frequency response for all disturbances during on-peak hours. c. By averaging the frequency response for all disturbances d. By averaging the frequency response for several disturbances during off-peak hours d. 21 Distance and a 64 Ground or 67 Directional Overcurrent -
ANSWERS -What type of relays would you most likely find on
each end of a 75 mile 230kV transmission line? a. 49 Thermals b. 27 Voltage or 25 Synchronous check c. 87 Differentials d. 21 Distance and a 64 Ground or 67 Directional Overcurrent
