NERC RC Exam UPDATED Exam
Questions and CORRECT Answers
What is ACE? - CORRECT ANSWER -(NIa - NIs) - 10β(fa - fs) - Ime
Calculated every 6 seconds
Uses Tie line Frequency Bias
What is Tie line deviation? - CORRECT ANSWER -Largest offset to ACE
What is NIA? - CORRECT ANSWER -Net Interchange Actual (sum of all tie-line values)
What is NIS? - CORRECT ANSWER -Net Interchange Scheduled (sum of all interchange
schedules)
What is the multiplier for frequency bias? - CORRECT ANSWER -10
What is β? - CORRECT ANSWER -Frequency bias - represented as negative number in
ACE calculation - reflects area natural response to frequency changes (Inertia, Governor, Load) -
atleast 1% of annual peak load for areas with native load - 1% of peak generation output for area
with no load
What is FA? - CORRECT ANSWER -Frequency Actual
What is FS? - CORRECT ANSWER -Frequency Schedule - normally 60.00 HZ except for
time corrections - +/- .02 Hz
What is IME? - CORRECT ANSWER -Meter error
fudge factor
used for inadvertent bilateral payback
,Negligible
What should be done if unable to calculate ACE for 30 minutes? - CORRECT ANSWER -
Contact RC
How often should time error and frequency devices be checked/calibrated? - CORRECT
ANSWER -Annually
Negative Ace - CORRECT ANSWER -The BA is Undergenerating
Positve ACE - CORRECT ANSWER -The BA is Overgenerating
What happens during Internal Loss of Load? - CORRECT ANSWER -Frequency and
ACE increase.
What happens during External Loss of Load? - CORRECT ANSWER -Frequency
increases, no change in ACE.
What is the Frequency Bias Setting? - CORRECT ANSWER -Monthly average >= 1% of
estimated yearly peak demand per 0.1 Hz
When should the Balancing Authority recalculate its Frequency Bias Setting? - CORRECT
ANSWER -By January 1 of each year
What happens when there is internal generation loss? - CORRECT ANSWER -Frequency
and ACE drop, tie-line flows increase into the system
What happens when there is external generation loss? - CORRECT ANSWER -Frequency
drops, no change in ACE, net tie-line flows increase out of the system
, What happens when Frequency bias setting is lower than frequency response? - CORRECT
ANSWER -ACE will be positive causing the AGC to lower generation
What is the percentage change in load required for a 1% change in frequency? - CORRECT
ANSWER -1% - 2% change in load
What is the load reduction when Transmission Customer Voltage is reduced by 5%? -
CORRECT ANSWER -Load will reduce by 3%
What happens to ACE and AGC when 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? - CORRECT ANSWER -ACE will be a
negative value and AGC will increase generation
What happens to ACE and AGC when 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? - CORRECT ANSWER -ACE will be a
positive value and AGC will lower generation
What is the normal schedule frequency? - CORRECT ANSWER -60.00 Hz
What is the frequency correction for fast clock schedule? - CORRECT ANSWER -59.98
Hz
What is the frequency corrections for a slow clock schedule? - CORRECT ANSWER -
60.02 Hz
When does frequency increase? - CORRECT ANSWER -Generation increases or load
decreases
When does frequency decrease? - CORRECT ANSWER -Generation decreases or load
increases
Questions and CORRECT Answers
What is ACE? - CORRECT ANSWER -(NIa - NIs) - 10β(fa - fs) - Ime
Calculated every 6 seconds
Uses Tie line Frequency Bias
What is Tie line deviation? - CORRECT ANSWER -Largest offset to ACE
What is NIA? - CORRECT ANSWER -Net Interchange Actual (sum of all tie-line values)
What is NIS? - CORRECT ANSWER -Net Interchange Scheduled (sum of all interchange
schedules)
What is the multiplier for frequency bias? - CORRECT ANSWER -10
What is β? - CORRECT ANSWER -Frequency bias - represented as negative number in
ACE calculation - reflects area natural response to frequency changes (Inertia, Governor, Load) -
atleast 1% of annual peak load for areas with native load - 1% of peak generation output for area
with no load
What is FA? - CORRECT ANSWER -Frequency Actual
What is FS? - CORRECT ANSWER -Frequency Schedule - normally 60.00 HZ except for
time corrections - +/- .02 Hz
What is IME? - CORRECT ANSWER -Meter error
fudge factor
used for inadvertent bilateral payback
,Negligible
What should be done if unable to calculate ACE for 30 minutes? - CORRECT ANSWER -
Contact RC
How often should time error and frequency devices be checked/calibrated? - CORRECT
ANSWER -Annually
Negative Ace - CORRECT ANSWER -The BA is Undergenerating
Positve ACE - CORRECT ANSWER -The BA is Overgenerating
What happens during Internal Loss of Load? - CORRECT ANSWER -Frequency and
ACE increase.
What happens during External Loss of Load? - CORRECT ANSWER -Frequency
increases, no change in ACE.
What is the Frequency Bias Setting? - CORRECT ANSWER -Monthly average >= 1% of
estimated yearly peak demand per 0.1 Hz
When should the Balancing Authority recalculate its Frequency Bias Setting? - CORRECT
ANSWER -By January 1 of each year
What happens when there is internal generation loss? - CORRECT ANSWER -Frequency
and ACE drop, tie-line flows increase into the system
What happens when there is external generation loss? - CORRECT ANSWER -Frequency
drops, no change in ACE, net tie-line flows increase out of the system
, What happens when Frequency bias setting is lower than frequency response? - CORRECT
ANSWER -ACE will be positive causing the AGC to lower generation
What is the percentage change in load required for a 1% change in frequency? - CORRECT
ANSWER -1% - 2% change in load
What is the load reduction when Transmission Customer Voltage is reduced by 5%? -
CORRECT ANSWER -Load will reduce by 3%
What happens to ACE and AGC when 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? - CORRECT ANSWER -ACE will be a
negative value and AGC will increase generation
What happens to ACE and AGC when 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? - CORRECT ANSWER -ACE will be a
positive value and AGC will lower generation
What is the normal schedule frequency? - CORRECT ANSWER -60.00 Hz
What is the frequency correction for fast clock schedule? - CORRECT ANSWER -59.98
Hz
What is the frequency corrections for a slow clock schedule? - CORRECT ANSWER -
60.02 Hz
When does frequency increase? - CORRECT ANSWER -Generation increases or load
decreases
When does frequency decrease? - CORRECT ANSWER -Generation decreases or load
increases
