NERC EXAM, TEST, PRACTICE EXAM AND STUDY GUIDE
LATEST ACTUAL EXAM
What is ACE? - ANSWER: (NIa - NIs) - 10β(fa - fs) - Ime
Calculated every 6 seconds
Uses Tie line Frequency Bias
What is Tie line deviation? - ANSWER: Largest offset to ACE
What is NIA? - ANSWER: Net Interchange Actual (sum of all tie-line values)
What is NIS? - ANSWER: Net Interchange Scheduled (sum of all interchange
schedules)
What is the multiplier for frequency bias? - ANSWER: 10
What is β? - 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? - ANSWER: Frequency Actual
What is FS? - ANSWER: Frequency Schedule - normally 60.00 HZ except for time
corrections - +/- .02 Hz
What is IME? - ANSWER: Meter error
fudge factor
used for inadvertent bilateral payback
Negligible
What should be done if unable to calculate ACE for 30 minutes? - ANSWER: Contact
RC
How often should time error and frequency devices be checked/calibrated? -
ANSWER: Annually
Negative Ace - ANSWER: The BA is Undergenerating
Positve ACE - ANSWER: The BA is Overgenerating
What happens during Internal Loss of Load? - ANSWER: Frequency and ACE increase.
What happens during External Loss of Load? - ANSWER: Frequency increases, no
change in ACE.
, What is the Frequency Bias Setting? - ANSWER: Monthly average >= 1% of estimated
yearly peak demand per 0.1 Hz
When should the Balancing Authority recalculate its Frequency Bias Setting? -
ANSWER: By January 1 of each year
What happens when there is internal generation loss? - ANSWER: Frequency and
ACE drop, tie-line flows increase into the system
What happens when there is external generation loss? - 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? -
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? -
ANSWER: 1% - 2% change in load
What is the load reduction when Transmission Customer Voltage is reduced by 5%? -
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? - 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? - ANSWER: ACE will be
a positive value and AGC will lower generation
What is the normal schedule frequency? - ANSWER: 60.00 Hz
What is the frequency correction for fast clock schedule? - ANSWER: 59.98 Hz
What is the frequency corrections for a slow clock schedule? - ANSWER: 60.02 Hz
When does frequency increase? - ANSWER: Generation increases or load decreases
When does frequency decrease? - ANSWER: Generation decreases or load increases
Who is the Time Monitor? - ANSWER: Can only be RC
one per Interconnection
Who is designated as Interconnection Time Monitor? - ANSWER: Single RC
designated by NERC Operating Committee
LATEST ACTUAL EXAM
What is ACE? - ANSWER: (NIa - NIs) - 10β(fa - fs) - Ime
Calculated every 6 seconds
Uses Tie line Frequency Bias
What is Tie line deviation? - ANSWER: Largest offset to ACE
What is NIA? - ANSWER: Net Interchange Actual (sum of all tie-line values)
What is NIS? - ANSWER: Net Interchange Scheduled (sum of all interchange
schedules)
What is the multiplier for frequency bias? - ANSWER: 10
What is β? - 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? - ANSWER: Frequency Actual
What is FS? - ANSWER: Frequency Schedule - normally 60.00 HZ except for time
corrections - +/- .02 Hz
What is IME? - ANSWER: Meter error
fudge factor
used for inadvertent bilateral payback
Negligible
What should be done if unable to calculate ACE for 30 minutes? - ANSWER: Contact
RC
How often should time error and frequency devices be checked/calibrated? -
ANSWER: Annually
Negative Ace - ANSWER: The BA is Undergenerating
Positve ACE - ANSWER: The BA is Overgenerating
What happens during Internal Loss of Load? - ANSWER: Frequency and ACE increase.
What happens during External Loss of Load? - ANSWER: Frequency increases, no
change in ACE.
, What is the Frequency Bias Setting? - ANSWER: Monthly average >= 1% of estimated
yearly peak demand per 0.1 Hz
When should the Balancing Authority recalculate its Frequency Bias Setting? -
ANSWER: By January 1 of each year
What happens when there is internal generation loss? - ANSWER: Frequency and
ACE drop, tie-line flows increase into the system
What happens when there is external generation loss? - 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? -
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? -
ANSWER: 1% - 2% change in load
What is the load reduction when Transmission Customer Voltage is reduced by 5%? -
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? - 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? - ANSWER: ACE will be
a positive value and AGC will lower generation
What is the normal schedule frequency? - ANSWER: 60.00 Hz
What is the frequency correction for fast clock schedule? - ANSWER: 59.98 Hz
What is the frequency corrections for a slow clock schedule? - ANSWER: 60.02 Hz
When does frequency increase? - ANSWER: Generation increases or load decreases
When does frequency decrease? - ANSWER: Generation decreases or load increases
Who is the Time Monitor? - ANSWER: Can only be RC
one per Interconnection
Who is designated as Interconnection Time Monitor? - ANSWER: Single RC
designated by NERC Operating Committee
