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NERC mix question | Actual Questions and Answers Latest Updated
2025 /202 6 (Graded A+)
The Disturbance Control Standard measures a Balancing Authority's response to a rapid loss of . demand for energy. interchange. ACE. supply of energy. - ✔✔supply of energy A Balancing Authority's largest single contingency is a unit rated at 1,000 MW. Which of the following disturbances would constitute a reportable disturbance for Disturbance Control Performance evaluation based on the NERC DCS criteria? The loss of a 950 MW generating unit at 100% output. The loss of 3 generating units totaling 1,300 MW over a period of 3 hours. The loss of a 750 MW generating unit at 100% output. The loss of 715 MW of firm load. - ✔✔The loss of a 950 MW generating unit at 100% output. Balancing Authority informs the Reliability Coordinator that the projected load in a Balancing Area for the next four hours (over the morning peak) is trending above the available generation that had been committed for the day. Operating Reserves will be required to be converted into energy to cover the shortfall. Which Energy Emergency Alert (EEA) level should the RC declare? No EEA should be declared until load shed is expected. EEA 1 EEA 2 EEA 3 - ✔✔EEA 1
A Balancing Authority anticipating an operating capacity or energy emergency shall perform all actions necessary which includes: Bringing on all available generation All answers are correct Preparing to reduce firm load Postponing equipment maintenance - ✔✔All answers are correct As a Transmission Operator, you realize that the voltage level is starting to decline in the North West part of the system. Which of the following devices should you, as a Transmission Operator, be able to operate, and/or have another entity operate to raise the voltage level back to normal in the North West part of the system? Generator Reactive Output Transformer Underload Tap Changers All answers are correct Shunt Capacitor Banks - ✔✔All answers are correct If a Balancing Authority, Reserve Sharing Group is experiencing conditions where all available resources are committed to meet firm load, firm transactions, and reserve commitments, what does the deficient entity need to request their Reliability Coordinator to issue? Energy Emergency Warning Energy Emergency Alert Level 2 Energy Emergency Alert Level 3 Energy Emergency Alert Level 1 - ✔✔Energy Emergency Alert Level 1 One of the functions of underfrequency load shedding is to within an electrical island that may have been created by a system disturbance. establish balance between load and interchange
A Balancing Authority foresees or is experiencing conditions where all available resources are committed to meet firm load, firm transactions. The BA should request which level of the Energy Emergency Alerts? Energy Emergency Alert Level 1 Energy Emergency Alert Level 4 Energy Emergency Alert Level 2 Energy Emergency Alert Level 3 - ✔✔Energy Emergency Alert Level 1 The System Operator experiences a major transmission system disturbance which results in a large loss of load. Which of the following results is most likely to occur? an increase in system frequency an increase in system voltage in a wide-area a decrease in system voltage a decrease in system frequency - ✔✔an increase in system frequency A Balancing Authority is assessing its system by reviewing the frequency at locations in its area and notices a frequency reading at one location varies significantly from the other locations. What might the Balancing Authority conclude? AGC is not working correctly. Interchange schedules are not correct. Frequency bias is not correct. An island condition has occurred - ✔✔An island condition has occurred A Transmission Operator is implementing their system restoration plan after a major system disturbance. When they are ready to energize a blacked out area, the system operator must . Close any capacitor banks which are open Increase blackstart generator to maximum output
Turn all voltage regulators to the manual position Isolate the load - ✔✔Isolate the load When a Balancing Authority has exhausted all other options and can no longer provide its customers' expected energy requirements, what can be used to obtain needed capacity and energy? Capacity Warning Demand Alert Imbalance Event Energy Emergency Alerts - ✔✔Energy Emergency Alerts The Interconnections is not experience any disturbances or overloads. A Balancing Authority notifies the Reliability Coordinator that the projected load in a Balancing Area for the next three hours (over the morning peak) is trending above the available generation that had been committed for the day. Operating Reserves will be required to be converted into energy to cover the shortfall. What is the most likely cause of the shortfall? The largest capacity generator in the Balancing Area tripped off line. The Load Forecast for the day was greatly underestimated. A generator operator failed to notify the Balancing Authority that one of their generators was de-rated by 30% of its capacity. There was a curtailment of the largest import on the Interchange Schedule. - ✔✔The Load Forecast for the day was greatly underestimated. The coordination of the emergency operating plans the Transmission Operator and Balancing Authority shall include which of the following? Process to prepare for and mitigate Emergencies All the above. Cancellation of transmission or generator outages Roles and responsibilities for activating operating plan - ✔✔All the above.
A Balancing Area has separated from the Interconnection during a severe thunder storm and is in a blackout condition. Several plants tripped off-line including a 200 MW blackstart capable unit and a blackstart capable hydro plant located 175 miles from the load center connected by a 345 kV system. What actions should the BA take to restore the area? Close all the breakers that tripped to the blackstart capable units. Isolate the transmission paths into the power plants, Bring the 200 MW blackstart unit on line to support the power plants auxiliaries, Add load in 10 MW blocks while increasing generation, Bring on additional generation. Open all breakers in area first then isolate the transmission paths into the power plants. Isolate the transmission paths into the power plants. Order the hydro plant on line and begin energizing customer loads. - ✔✔Isolate the transmission paths into the power plants, Bring the 200 MW blackstart unit on line to support the power plants auxiliaries, Add load in 10 MW blocks while increasing generation, Bring on additional generation. Once a deficient Balancing Authority informs the Reliability Coordinator of future or current Capacity and Energy Emergencies, it is the responsibility of the to mitigate the emergency condition? Reliability Coordinator Transmission Operator Transmission Owner Deficient Balancing Authority - ✔✔Deficient Balancing Authority The load in Balancing Authority "A" is currently 2000 MWs. The Interconnection frequency drops from 60.00 Hz to 59.70 Hz due to a disturbance in another Balancing Authority. What change in load can BA "A" expect to see? The load should increase approximately 40 MWs. The load should decrease approximately 40 MWs. The load should decrease approximately 20 MWs. The load should increase approximately 20 MWs - ✔✔The load should decrease approximately 20 MWs.
Load on the power system changes with frequency. For every 1% change in frequency, - ✔✔change approximately 2% in the same direction After declaring an NERC EEA Level 3, load goes higher than your generation resources, what is an effective tool in restoring generation to load balance? Voltage Reduction Exceeding emergency limits Firm Load Shed TLR - ✔✔Firm Load Shed If you are still in an emergency after utilizing your own reserves and readily available operating reserve and your own resources including scheduling assistance from others, you should. put reactor banks in service manually shed load reduce voltage on the transmission system - ✔✔manually shed load A report shall be submitted to NERC following the shedding of a least how much firm load? 100 MW 50 MW 300 MW 200 MW - ✔✔ 100 MW You are a Reliability Coordinator experiencing a flow gate that has become overloaded because a parallel 345 kV line has relayed out causing an SOL violation and possible IROL violation. What would you do to relieve this violation?
A Transmission Operator area has an instantaneous automatic Under-Frequency Load Shed Scheme segmented into a sequence of 4 Steps: Step 1 = 59.500Hz. removes 25MW; Step 2 = 59.300Hz. removes 20MW; Step 3 = 59.100Hz. removes 20MW; Step 4 = 58.900Hz. removes an additional 15MW. Step 3 & 4 will automatically reset and re-close restoring load when the frequency returns to 60.00 Hz. A large event occurs causing the system frequency to fall to 59.000Hz. and returns to 60.00Hz after 12 minutes. Assuming a constant load factor, what is the total load the TOP must restore manually once the frequency has recovered to 60.000Hz.? 25 MW 45 MW 80 MW 65 MW - ✔✔ 45 MW A Transmission Operator anticipating load reductions to support voltage, must notify which entities? The Reliability Coordinator only All Balancing authorities and Transmission Operators Its Reliability Coordinator and known impacted Balancing Authorities and Transmission Operators The Interconnection via interconnection communications - ✔✔Its Reliability Coordinator and known impacted Balancing Authorities and Transmission If a Balancing Authority is unable to purchase capacity or energy to meet its demand and reserve requirements on a day-ahead or hour-by-hour basis, which entity (or entities), is it expected to notify? All Reliability Coordinators. Transmission Operators
Its Reliability Coordinator and other Balancing Authorities All Reliability Coordinators and Marketers - ✔✔Its Reliability Coordinator and other Balancing Authorities Which of the following would be techniques in managing an approaching System Operating Limit violation or IROL violation? Removing overloaded transmission facilities Re-dispatch, Reduce Interchange or Load Shed Replace transmission lines Reduce power flow by denying market activity - ✔✔Re-dispatch, Reduce Interchange or Load Shed When two identical A/C generating units are operated in parallel on governor control, and one machine has a 5% droop and the other has a 10% droop, the unit with the greater governor droop will... Tend to take the greater portion of load changes. Share load equally with the other machine. Tend to take the lesser portion of load changes. No adjustment for frequency changes. - ✔✔Tend to take the lesser portion of load changes. The lower the droop % - ✔✔the more a unit will respond to a frequency deviation. - Geomagnetic Disturbance can impact the power system in what way? Generator output varies Transformers can become saturated Abnormal VAR direction Increase static electricity - ✔✔Transformers can become saturated
The point where irreversible damage occurs in an element - ✔✔Local operating boundaries A System Operator must operate the transmission system so that instability, uncontrolled separation, or cascading outages will not occur as a result of. External disturbances Normal operations The most severe single contingency Any unplanned outage - ✔✔The most severe single contingency Transmission line AB has a SOL of 375 is currently loaded at 450. Generator A has a shift factor of (- .50) and Generator B has a shift factor of (.25) related to this line. If these are the only units available to relieve the overload, what would be the re-dispatch order to relieve the overloaded line? Decrease Gen B 100 and increase Gen A 100. Decrease Gen A 50 and decrease Gen B 25. Increase Gen B by 25 and decrease Gen A 50. Decrease Gen A 100 and increase Gen B 100. - ✔✔Decrease Gen B 100 and increase Gen A 100. Which entity integrates resource plans ahead of time, maintains load-interchange-generation balance within a Balancing Authority Area, and supports Interconnection frequency in real time? Transmission Operator Regional Reliability Organization Reliability Coordinator Balancing Authority - ✔✔Balancing Authority The load on a power transformer is 80 MW and 60 MVAR. What is the Power Factor at the transformer? .90 PF
.57 PF
.75 PF
.80 PF - ✔✔.80 PF
Which action (s) does a Reliability Coordinator have the authority to direct all reliability entities within its area to take to return the system to a reliable state. Re-dispatch generation Re-configure transmission Reduce load All the Above - ✔✔All the Above A Generator Operator has determined that one of its generators cannot meet its maximum rated reactive power due to bearing vibration. Which of the following actions should the Generator Operator take? Should take the generator off line until problem can be fixed. No action is required. Should notify its Transmission Operator of the new limit. Should place the AVR in manual and increase MVARs to maximum. - ✔✔Should notify its Transmission Operator of the new limit. If a Transmission Operator is experiencing an SOL and anticipates having to shed firm load to return to within limits, which entity (ies) must be notified? Its Reliability Coordinator and all other potentially affected Balancing Authorities and Transmission Operators. Its Reliability Coordinator only. All Reliability Coordinators and Balancing Authorities. All Reliability Coordinators and all Balancing Authorities and Transmission Operators. - ✔✔Its Reliability Coordinator and all other potentially affected Balancing Authorities and Transmission Operators.
In a power system, which type of power provides indication of voltage problems, is critical for support of heavily loaded transmission lines, and is necessary to have sufficient dynamic reserves in preparation for a contingency? Real Power Solar Power Apparent Power Reactive Power - ✔✔Reactive Power A car on a city street hit a 13kV power pole causing A and B phases to wrap around each other. The 13kV line relays at the substation fail to trip the 13kV circuit breaker feeding the troubled line. Which relay will likely pick up and trip the 138/13kV transformer feeding the 13kV system off line to protect it from damage. Phase Comparison Timed Overcurrent Differential Ground - ✔✔Timed Overcurrent Two generating units are operated in parallel. Generator A is 500 MWs with a droop setting of 3%, and Generator B is 1000 MWs with a droop setting of 6%. Which generator will have the greater response to a frequency drop on the system? Both generators should respond the same. Generator A will respond more. The response would be determined by the Frequency Bias Setting. Generator B will respond more. - ✔✔Both generators should respond the same. A Transmission line is loaded at 125% of its System Operating Limit. A parallel line is out for structure maintenance and will take several hours to return to service. Which of the following actions would be acceptable in these conditions?
Open the overloaded line immediately. Decrease the voltage setpoints on the generators in the area Re-dispatch generation to decrease loading on the line. Wait until the parallel line is restored. A 25% overload is acceptable as long as the parallel line is returned by the end of the day. - ✔✔Re-dispatch generation to decrease loading on the line. What is a contingency? The unexpected loss of telecommunications An operating procedure The unexpected failure of a system component Actual loading on a circuit - ✔✔The unexpected failure of a system component A line is operating at 125% (25% above its SOL) following several parallel line outages caused by a severe storm. The flow on this line is from Bus A, which is north, to Bus B, which is south. As a system operator you decide to use generation redispatch to relieve the line loading problem. Your course of action should be to. Decrease generation on the north side of Bus A and increase the generation on the south side of Bus B. Increase generation on the north side of Bus A and increase generation on the south side of Bus B. Decrease generation on the north side of Bus A and decrease generation on the south side of Bus B. Increase generation on the north side of Bus A, and decrease generation on the south side of Bus B. - ✔✔Decrease generation on the north side of Bus A and increase the generation on the south side of Bus B. The Transmission Operator shall develop, maintain, and implement one or more Reliability Coordinator- reviewed Operating Plan. What is the purpose of Operating Plans? To address and mitigate operating Emergencies Notify all Reliability Coordinators in NERC Notify the Reliability Coordinator
change on the ULTC to raise low side voltage as the high and low side voltages become closer together in magnitude? The high side voltage will increase. The high side voltage will stay the same. The low side voltage will increase very little. The low side voltage will increase considerably. - ✔✔The low side voltage will increase very little You receive an alarm that indicates low oil pressure on a underground transmission cable. SCADA shows the pressure is continuing to drop. What is the first step you would take to protect the line? Notify field personnel to identify the problem. Isolate the line. Schedule maintenance for the next day. Lower the line loading and dispatch maintenance personnel. - ✔✔Isolate the line. In order to predict the systems near term load pattern, a system operator must have information including weather forecasts and. Sufficient metering Generator overhaul schedules Past load patterns Generator efficiency ratings - ✔✔Past load patterns The Transmission Operator should not consider which of the following when reactive resources are limited? Request reactive power support from neighboring systems. Re-dispatch if necessary, even if running outside of the economic dispatch is necessary. Shed load only after neighbors have shed load.
Shift system generation patterns to unload heavily loaded lines - ✔✔Shed load only after neighbors have shed load. What is the purpose of a Transformer? Changing the voltage levels of electricity Allows for efficient long-distance transfer of electricity Minimize losses in the power system All the Above - ✔✔All the Above Part of a Transmission Operator's system has exceeded a System Operating Limit. The Transmission Operator has reported both the event and actions it is taking to the Reliability Coordinator. After 20 minutes, it is apparent to the Reliability Coordinator that the actions being taken will not return the system to within limits. What is the appropriate action for the Reliability Coordinator at this point? Wait for another ten minutes to see if the Transmission Operator comes up with actions to return the system to within limits. Remind the Transmission Operator that only ten minutes remain to return the system to within limits. None of these answers provide an appropriate action. Direct the Transmission Operator to take actions that will return the system to within limits. - ✔✔Direct the Transmission Operator to take actions that will return the system to within limits What is a thermal rating? Transmission line sagging capability Maximum amount of current before overheating damage occurs Heat Source Maximum load that can be transformed - ✔✔Maximum amount of current before overheating damage occurs
