SOS NERC PREP – EXAM QUESTIONS
WITH CORRECT ANSWERS
The Reliability Coordinator just informed you of a slow time error correction which will
begin at the top of the next hour. Your EMS system will not let you change your
scheduled frequency. Your Frequency Bias Setting is -100 MW/.1Hz. What action
should you take?
A) Increase Net Interchange Schedule by 20 MWs.
B) Inform the Reliability Coordinator that you cannot participate in the time error
correction.
C) Decrease Net Interchange Schedule by 20 MWs.
D) Increase Net Interchange Schedule by 10 MWs. - Answer-A) Increase Net
Interchange Schedule by 20 MWs.
A Balancing Authority has a sudden loss of a large block of load in its area. This loss
will be seen instantaneously in the change of which of the following values?
1. Actual Net Interchange
2. Scheduled Frequency
3. Scheduled Net Interchange
4. Area Control Error
A) 4 only
B) 1 & 3
C) 1 & 4
D) 3 & 4 - Answer-C) 1 & 4
Metered Data included in the calculation of ACE are: dynamic schedules, pseudo ties,
actual frequency, and all __________.
A) Tie lines readings
B) Generators output
C) Scheduled frequency indications
D) Transformer load - Answer-A) Tie lines readings
Balancing Authority A is currently reading a system frequency of 60.00 Hz. Its Net
Actual Interchange is +100 MW and its Net Scheduled Interchange is +200 MW. If
Balancing Authority A's frequency bias setting is 100 MW/0.1 Hz, what is ACE?
A) -100
B) 0
,C) 10
D) 100 - Answer-A) -100
A Balancing Authority has a Net Interchange Schedule of -250 MWs from 1200 to 1600
on a summer day. The Net Interchange Actual for those same hours respectively were -
230 MW, -275 MW, -250 MW and -270 MW. What was the Balancing Authority's
Inadvertent Interchange for the 4-hour period?
A) 6 MWs out
B) 25 MWs in
C) 25 MWs out
D) 6 MWs in - Answer-B) 25 MWs in
For the ACE equation to work properly, dynamic schedules, pseudo ties, frequency, and
all ________________ must be metered.
A) Generation
B) Communications
C) Transformers
D) Tie lines - Answer-D) Tie lines
If the frequency bias setting is set to a less negative value than the frequency response
of a Balancing Authority and a frequency increase is caused by a sudden loss of load in
an external balancing area, what will be the result?
A) The ACE will be zero and will take no AGC action
B) The ACE will be a negative value and AGC will increase generation
C) The ACE will be a positive value and AGC will lower generation
D)This will not affect the ACE - Answer-B) The ACE will be a negative value and AGC
will increase generation
If the frequency bias setting is less negative 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 negative value and AGC will increase generation.
B) This will not affect the ACE.
C) The ACE will be a positive value and AGC will lower generation.
D) The ACE will be zero and will take no AGC action. - Answer-C) The ACE will be a
positive value and AGC will lower generation.
,It is the responsibility of which entity/entities to develop, maintain, and implement load
shedding plans?
A) Transmission Operators and Balancing Authorities
B) Reliability Coordinator
C) Load Serving Entities
D) Balancing Authority - Answer-A) Transmission Operators and Balancing Authorities
A Transmission line is loaded 25% above its SOL. A parallel line is out for routine
maintenance and can be placed in service in 10 minutes. What is the first step the
Operator should take to reduce the line loading?
A)Shed load at the downstream bus.
B) Open the line.
C) Re-Dispatch Generation.
D) Initiate the restoration of the parallel line. - Answer-D) Initiate the restoration of the
parallel line.
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?
A) Transformer Underload Tap Changers
B) Shunt Capacitor Banks
C) Generator Reactive Output
D) All answers are correct - Answer-D) All answers are correct
Voltage reduction for load relief should be made on the __________.
A) Distribution system
B) Entire Interconnection simultaneously
C) Tie-lines with other Balancing Authority Areas
D) Transmission System - Answer-A) Distribution system
Under Frequency Load Shedding (UFLS) is to stabilize the imbalance between
generation and load that has been created by a system disturbance. This is
accomplished by ____________.
, A) Tripping generation first
B) Voltage reduction on the distribution system.
C) Shedding all load to arrest frequency
D) Shedding load prior to generation tripping - Answer-D) Shedding load prior to
generation tripping
Failure to meet the DCS criteria of recovery within 15 minutes results in which
consequence for a specified time period for the Balancing Authority's failure to recover?
A) Increased Contingency Reserve requirements
B) Decertification as a Balancing Authority
C) Not allowed to supply regulation services
D) Expulsion from the Reserve Sharing Group - Answer-A) Increased Contingency
Reserve requirements
A Balancing Authority foresees or is experiencing conditions where all available
resources are committed to meet firm load, and firm transactions. The BA should
request which level of the Energy Emergency Alerts?
A) Energy Emergency Alert Level 2
B) Energy Emergency Alert Level 4
C) Energy Emergency Alert Level 1
D) Energy Emergency Alert Level 3 - Answer-C) Energy Emergency Alert Level 1
Preparations are being made to tie two islands together during restoration. Island "A"
has a frequency of 58.95 Hz and Island "B" has a frequency of 59.97 Hz. What action
should be taken to synchronize the two islands?
A) Shed load in Island "B"
B) Shed load in Island "A".
C) Disable the Synch Check Relay.
D) Increase generation in Island "B". - Answer-B) Shed load in Island "A".
You experience a full system shutdown. You are in the process of restoring load and
you are concerned about re-collapsing the system. Which is the best approach in the
restoration process that will help ensure your system will be restored successfully?
A) Maintain frequency between 59.5 HZ and 60.5 HZ.
B) If the system has stabilized at below 60 HZ, shed 15% - 20% of the load to raise the
frequency to 61 HZ.
C) Avoid energizing loads in excess of 5% of the online generation capacity of the
system.
WITH CORRECT ANSWERS
The Reliability Coordinator just informed you of a slow time error correction which will
begin at the top of the next hour. Your EMS system will not let you change your
scheduled frequency. Your Frequency Bias Setting is -100 MW/.1Hz. What action
should you take?
A) Increase Net Interchange Schedule by 20 MWs.
B) Inform the Reliability Coordinator that you cannot participate in the time error
correction.
C) Decrease Net Interchange Schedule by 20 MWs.
D) Increase Net Interchange Schedule by 10 MWs. - Answer-A) Increase Net
Interchange Schedule by 20 MWs.
A Balancing Authority has a sudden loss of a large block of load in its area. This loss
will be seen instantaneously in the change of which of the following values?
1. Actual Net Interchange
2. Scheduled Frequency
3. Scheduled Net Interchange
4. Area Control Error
A) 4 only
B) 1 & 3
C) 1 & 4
D) 3 & 4 - Answer-C) 1 & 4
Metered Data included in the calculation of ACE are: dynamic schedules, pseudo ties,
actual frequency, and all __________.
A) Tie lines readings
B) Generators output
C) Scheduled frequency indications
D) Transformer load - Answer-A) Tie lines readings
Balancing Authority A is currently reading a system frequency of 60.00 Hz. Its Net
Actual Interchange is +100 MW and its Net Scheduled Interchange is +200 MW. If
Balancing Authority A's frequency bias setting is 100 MW/0.1 Hz, what is ACE?
A) -100
B) 0
,C) 10
D) 100 - Answer-A) -100
A Balancing Authority has a Net Interchange Schedule of -250 MWs from 1200 to 1600
on a summer day. The Net Interchange Actual for those same hours respectively were -
230 MW, -275 MW, -250 MW and -270 MW. What was the Balancing Authority's
Inadvertent Interchange for the 4-hour period?
A) 6 MWs out
B) 25 MWs in
C) 25 MWs out
D) 6 MWs in - Answer-B) 25 MWs in
For the ACE equation to work properly, dynamic schedules, pseudo ties, frequency, and
all ________________ must be metered.
A) Generation
B) Communications
C) Transformers
D) Tie lines - Answer-D) Tie lines
If the frequency bias setting is set to a less negative value than the frequency response
of a Balancing Authority and a frequency increase is caused by a sudden loss of load in
an external balancing area, what will be the result?
A) The ACE will be zero and will take no AGC action
B) The ACE will be a negative value and AGC will increase generation
C) The ACE will be a positive value and AGC will lower generation
D)This will not affect the ACE - Answer-B) The ACE will be a negative value and AGC
will increase generation
If the frequency bias setting is less negative 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 negative value and AGC will increase generation.
B) This will not affect the ACE.
C) The ACE will be a positive value and AGC will lower generation.
D) The ACE will be zero and will take no AGC action. - Answer-C) The ACE will be a
positive value and AGC will lower generation.
,It is the responsibility of which entity/entities to develop, maintain, and implement load
shedding plans?
A) Transmission Operators and Balancing Authorities
B) Reliability Coordinator
C) Load Serving Entities
D) Balancing Authority - Answer-A) Transmission Operators and Balancing Authorities
A Transmission line is loaded 25% above its SOL. A parallel line is out for routine
maintenance and can be placed in service in 10 minutes. What is the first step the
Operator should take to reduce the line loading?
A)Shed load at the downstream bus.
B) Open the line.
C) Re-Dispatch Generation.
D) Initiate the restoration of the parallel line. - Answer-D) Initiate the restoration of the
parallel line.
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?
A) Transformer Underload Tap Changers
B) Shunt Capacitor Banks
C) Generator Reactive Output
D) All answers are correct - Answer-D) All answers are correct
Voltage reduction for load relief should be made on the __________.
A) Distribution system
B) Entire Interconnection simultaneously
C) Tie-lines with other Balancing Authority Areas
D) Transmission System - Answer-A) Distribution system
Under Frequency Load Shedding (UFLS) is to stabilize the imbalance between
generation and load that has been created by a system disturbance. This is
accomplished by ____________.
, A) Tripping generation first
B) Voltage reduction on the distribution system.
C) Shedding all load to arrest frequency
D) Shedding load prior to generation tripping - Answer-D) Shedding load prior to
generation tripping
Failure to meet the DCS criteria of recovery within 15 minutes results in which
consequence for a specified time period for the Balancing Authority's failure to recover?
A) Increased Contingency Reserve requirements
B) Decertification as a Balancing Authority
C) Not allowed to supply regulation services
D) Expulsion from the Reserve Sharing Group - Answer-A) Increased Contingency
Reserve requirements
A Balancing Authority foresees or is experiencing conditions where all available
resources are committed to meet firm load, and firm transactions. The BA should
request which level of the Energy Emergency Alerts?
A) Energy Emergency Alert Level 2
B) Energy Emergency Alert Level 4
C) Energy Emergency Alert Level 1
D) Energy Emergency Alert Level 3 - Answer-C) Energy Emergency Alert Level 1
Preparations are being made to tie two islands together during restoration. Island "A"
has a frequency of 58.95 Hz and Island "B" has a frequency of 59.97 Hz. What action
should be taken to synchronize the two islands?
A) Shed load in Island "B"
B) Shed load in Island "A".
C) Disable the Synch Check Relay.
D) Increase generation in Island "B". - Answer-B) Shed load in Island "A".
You experience a full system shutdown. You are in the process of restoring load and
you are concerned about re-collapsing the system. Which is the best approach in the
restoration process that will help ensure your system will be restored successfully?
A) Maintain frequency between 59.5 HZ and 60.5 HZ.
B) If the system has stabilized at below 60 HZ, shed 15% - 20% of the load to raise the
frequency to 61 HZ.
C) Avoid energizing loads in excess of 5% of the online generation capacity of the
system.
