KNOWN NERC EXAM QUESTIONS
AND ANSWERS: From Class
A transmission line in your area is overloaded by 50 MWs. An area generator has a .25
shift factor on the line. How much generation change is required to return the line to its
limit?
a) 50 MWs
b) 100 MWs
c) 200 MWs
d) 250 MWs - CORRECT ANSWER- c) 200 MWs
A study shows that a single contingency would result in an IROL violation and the
corrective action would require opening a breaker with no SCADA control due to a failed
RTU. What should the system operator do first?
a ) Dispatch field personnel to the breakers substation
b) Shed load near the IROL location
c) Re-dispatch generation to reduce line loading
d) Develop a new response plan for the contingency - CORRECT ANSWER- a )
Dispatch field personnel to the breakers substation
A Balancing Authority notices that Operating Reserve has steadily declined throughout
the hour. What is the most likely cause?
a) Loss of a large generator in the area
b) An inaccurate load forecast
c) Loss of a major transmission line
d) A malfunction of EMS - CORRECT ANSWER- b) An inaccurate load forecast
Balancing Area A notices that the Interconnection frequency is 59.94 Hz and their ACE
is 0. Which of the following could be the cause of this reading?
a) A net under-generation in Balancing Area A
b) A net under-generation in the Interconnection
c) A loss of load in Balancing Area A
d) A loss of load in the Interconnection - CORRECT ANSWER- b) A net under-
generation in the Interconnection
What is the penalty for a Balancing Authority violating the Disturbance Control
Standard?
a) Must carry additional Contingency Reserve
b) Must develop a correction action plan
, c) Must re-evaluate and change its Frequency Bias Setting
d) Must increase its Regulating Reserve - CORRECT ANSWER- a) Must carry
additional Contingency Reserve
Your ACE is a large negative value and system frequency is 59.80 Hz. Your AGC
system is pulsing your units down. What should you do?
a) Place AGC in flat frequency control
b) Place AGC in flat tie line control
c) Suspend AGC and investigate
d) Do nothing as this is normal - CORRECT ANSWER- c) Suspend AGC and
investigate
When two identical generating units are operated in parallel on governor control, and on
machine has a 5% droop and the other has a 10% droop, the unit with the greater
(10%) governor droop will:
a) Respond less to frequency deviations
b) Respond more to frequency deviations
c) Respond the same to frequency deviations
d) Not adjust for frequency changes - CORRECT ANSWER- a) Respond less to
frequency deviations
On a radial transmission system a generator has a capacity of 600 MWs. The Droop
characteristic is at 5% and the generator is currently loaded at 300 MWs. If frequency
suddenly drops to 59.3 Hz, what would be the total generator output?
a) 350
b) 400
c) 440
d) 600 - CORRECT ANSWER- c) 440
What is the main purpose of the Frequency Bias Setting in the ACE equation?
a) Control frequency to 60 Hz for the entire Interconnection
b) Assist with arresting frequency deviations
c) Restore frequency to 60 Hz after a disturbance
d) maintains frequency between 59.95 and 60.05 Hz - CORRECT ANSWER- b)
Assist with arresting frequency deviations
A Balancing Authority has a Frequency Bias Setting of -200 MW/.1Hz. What is the
Balancing Authority's Frequency Response for a frequency of 59.95 Hz?
a) 10 MWs
b) 50 MWs
c) 100 MWs
AND ANSWERS: From Class
A transmission line in your area is overloaded by 50 MWs. An area generator has a .25
shift factor on the line. How much generation change is required to return the line to its
limit?
a) 50 MWs
b) 100 MWs
c) 200 MWs
d) 250 MWs - CORRECT ANSWER- c) 200 MWs
A study shows that a single contingency would result in an IROL violation and the
corrective action would require opening a breaker with no SCADA control due to a failed
RTU. What should the system operator do first?
a ) Dispatch field personnel to the breakers substation
b) Shed load near the IROL location
c) Re-dispatch generation to reduce line loading
d) Develop a new response plan for the contingency - CORRECT ANSWER- a )
Dispatch field personnel to the breakers substation
A Balancing Authority notices that Operating Reserve has steadily declined throughout
the hour. What is the most likely cause?
a) Loss of a large generator in the area
b) An inaccurate load forecast
c) Loss of a major transmission line
d) A malfunction of EMS - CORRECT ANSWER- b) An inaccurate load forecast
Balancing Area A notices that the Interconnection frequency is 59.94 Hz and their ACE
is 0. Which of the following could be the cause of this reading?
a) A net under-generation in Balancing Area A
b) A net under-generation in the Interconnection
c) A loss of load in Balancing Area A
d) A loss of load in the Interconnection - CORRECT ANSWER- b) A net under-
generation in the Interconnection
What is the penalty for a Balancing Authority violating the Disturbance Control
Standard?
a) Must carry additional Contingency Reserve
b) Must develop a correction action plan
, c) Must re-evaluate and change its Frequency Bias Setting
d) Must increase its Regulating Reserve - CORRECT ANSWER- a) Must carry
additional Contingency Reserve
Your ACE is a large negative value and system frequency is 59.80 Hz. Your AGC
system is pulsing your units down. What should you do?
a) Place AGC in flat frequency control
b) Place AGC in flat tie line control
c) Suspend AGC and investigate
d) Do nothing as this is normal - CORRECT ANSWER- c) Suspend AGC and
investigate
When two identical generating units are operated in parallel on governor control, and on
machine has a 5% droop and the other has a 10% droop, the unit with the greater
(10%) governor droop will:
a) Respond less to frequency deviations
b) Respond more to frequency deviations
c) Respond the same to frequency deviations
d) Not adjust for frequency changes - CORRECT ANSWER- a) Respond less to
frequency deviations
On a radial transmission system a generator has a capacity of 600 MWs. The Droop
characteristic is at 5% and the generator is currently loaded at 300 MWs. If frequency
suddenly drops to 59.3 Hz, what would be the total generator output?
a) 350
b) 400
c) 440
d) 600 - CORRECT ANSWER- c) 440
What is the main purpose of the Frequency Bias Setting in the ACE equation?
a) Control frequency to 60 Hz for the entire Interconnection
b) Assist with arresting frequency deviations
c) Restore frequency to 60 Hz after a disturbance
d) maintains frequency between 59.95 and 60.05 Hz - CORRECT ANSWER- b)
Assist with arresting frequency deviations
A Balancing Authority has a Frequency Bias Setting of -200 MW/.1Hz. What is the
Balancing Authority's Frequency Response for a frequency of 59.95 Hz?
a) 10 MWs
b) 50 MWs
c) 100 MWs
