NERC 601 Exam Study Guide | Actual Questions and Answers
Latest Updated 2026/2027 (Graded A+)
•
What is the ACE equation?
- ✔✔(NIa-NIs)-10B(Fa-Fs)
•
What effect does an internal loss of load have on frequency and ACE?
- ✔✔Frequency increases, ACE increases
•
What effect does an external loss of load have on frequency and ACE?
- ✔✔Frequency increases, No change in ACE
•
What happens to your frequency, ACE value, and Tie-line flow when you experience a loss of
generation external to your area?
- ✔✔Frequency drops, No change in ACE, Tie-line flows increase out of your system
•
What happens to your frequency, ACE value, and Tie-line flow when you experience a loss of
generation inside your balancing area?
- ✔✔Frequency drops, ACE drops, Tie-flows increase into your area
•
How is Frequency Response Obligation (FRO) calculated?
- ✔✔It is calculated based on the BA's annual percentage of generation and load in it's
interconnection
•
How is the FRO of a Frequency Response Sharing Group calculated?
- ✔✔FRO determined by adding individual FROs of each member
•
How is the Frequency Response Measure (FRM) calculated?
- ✔✔It is the median of all frequency responses observed for frequency deviations events
identifies by NERC for the previous year
•
How should the Frequency Response Measure be set compared to the Frequency Response
Obligation?
- ✔✔Frequency Response Measure should be set equal to or more negative than Frequency
Response Obligation
•
Who determines your Frequency Bias Setting?
,- ✔✔It is determined by NERC based on previous years Frequency Response Measure
•
What is CPS 1 (Control Performance Standard)?
- ✔✔One minute clock average over a year and is based on ACE deviation in correlation to
frequency deviation. CPS 1 has a 100% minimum compliance. Measures how well a BA
balances load and generation to support the interconnection.
•
What is BAAL (Balancing Authority ACE Limit)?
- ✔✔ACE does not exceed its BAAL for more than 30 consecutive minutes
•
When does BAAL high apply? When does BAAL low apply?
i. - ✔✔BAAL high applies when frequency actual is greater than frequency scheduled
ii. BAAL low applies when frequency actual is lower than frequency scheduled
•
What is DCS and what is the minimum compliance for DCS (Disturbance Control Standard)?
- ✔✔100% compliance, Measures BA's ability to carry adequate Operating Reserve
•
What is the time limit for Disturbance Recovery Period?
- ✔✔15 minutes
•
If ACE is positive or 0 at the time of a DCS event what does have to be returned to and in what time?
- ✔✔ACE of 0 in 15 minutes
•
If ACE is negative at the time of a DCS event what does ACE have to be returned to and in what time?
- ✔✔ACE must be returned to the negative pre-contingency value in 15 minutes
•
Your MSSC is 160 MW. You have an ACE Value of 0 when a DCS event causes ACE to drop 100 MW.
90 seconds later you have another event that causes ACE to drop an additional 50 MW. What value
must ACE be returned to?
- ✔✔-100
•
What is considered a DCS event?
- ✔✔A loss of generation greater than or equal to 80% of your MSSC, multiple generator
losses are considered a single event if occurring within 60 seconds of each other.
•
When does the Contingency Reserve restoration period begin? How long do you have to restore
contingency reserve equal to your MSSC?
, - ✔✔At the end of the Disturbance control recovery period, 90 minutes
•
What makes up Operating reserves?
- ✔✔Regulating reserves (must be spinning), Contingency reserves (both spinning and
non-spinning)
•
How much of your contingency reserve should be spinning reserves?
- ✔✔50%
•
What is Regulating reserves used for?
- ✔✔Used to meet load forecasting errors, system tie-line and frequency regulation needs
•
What can be considered contingency reserve?
- ✔✔Generation, controllable load, coordinated adjustments to interchange schedules
•
For controllable load to be considered a contingency reserve what must it be?
- ✔✔must be available within 15 minutes
•
For generation to be considered spinning contingency reserve what must it be?
- ✔✔must be synchronized to the system and available within the DCS period
•
What is State Estimator?
- ✔✔A real time model of the current conditions of the power system
•
What is Contingency analysis? what does Contingency analysis rely on? How often should
Contingency analysis be ran?
- ✔✔evaluates potential outages and their impact on the remaining system, relies on State
Estimator values, should be ran every 30 minutes
•
what is the scan rate for ACE related data?
- ✔✔6 seconds
•
What must a BA experience to declare an EEA?
- ✔✔the BA is or expects to be unable to provide its customers load demands
•
Who request an EEA?
Latest Updated 2026/2027 (Graded A+)
•
What is the ACE equation?
- ✔✔(NIa-NIs)-10B(Fa-Fs)
•
What effect does an internal loss of load have on frequency and ACE?
- ✔✔Frequency increases, ACE increases
•
What effect does an external loss of load have on frequency and ACE?
- ✔✔Frequency increases, No change in ACE
•
What happens to your frequency, ACE value, and Tie-line flow when you experience a loss of
generation external to your area?
- ✔✔Frequency drops, No change in ACE, Tie-line flows increase out of your system
•
What happens to your frequency, ACE value, and Tie-line flow when you experience a loss of
generation inside your balancing area?
- ✔✔Frequency drops, ACE drops, Tie-flows increase into your area
•
How is Frequency Response Obligation (FRO) calculated?
- ✔✔It is calculated based on the BA's annual percentage of generation and load in it's
interconnection
•
How is the FRO of a Frequency Response Sharing Group calculated?
- ✔✔FRO determined by adding individual FROs of each member
•
How is the Frequency Response Measure (FRM) calculated?
- ✔✔It is the median of all frequency responses observed for frequency deviations events
identifies by NERC for the previous year
•
How should the Frequency Response Measure be set compared to the Frequency Response
Obligation?
- ✔✔Frequency Response Measure should be set equal to or more negative than Frequency
Response Obligation
•
Who determines your Frequency Bias Setting?
,- ✔✔It is determined by NERC based on previous years Frequency Response Measure
•
What is CPS 1 (Control Performance Standard)?
- ✔✔One minute clock average over a year and is based on ACE deviation in correlation to
frequency deviation. CPS 1 has a 100% minimum compliance. Measures how well a BA
balances load and generation to support the interconnection.
•
What is BAAL (Balancing Authority ACE Limit)?
- ✔✔ACE does not exceed its BAAL for more than 30 consecutive minutes
•
When does BAAL high apply? When does BAAL low apply?
i. - ✔✔BAAL high applies when frequency actual is greater than frequency scheduled
ii. BAAL low applies when frequency actual is lower than frequency scheduled
•
What is DCS and what is the minimum compliance for DCS (Disturbance Control Standard)?
- ✔✔100% compliance, Measures BA's ability to carry adequate Operating Reserve
•
What is the time limit for Disturbance Recovery Period?
- ✔✔15 minutes
•
If ACE is positive or 0 at the time of a DCS event what does have to be returned to and in what time?
- ✔✔ACE of 0 in 15 minutes
•
If ACE is negative at the time of a DCS event what does ACE have to be returned to and in what time?
- ✔✔ACE must be returned to the negative pre-contingency value in 15 minutes
•
Your MSSC is 160 MW. You have an ACE Value of 0 when a DCS event causes ACE to drop 100 MW.
90 seconds later you have another event that causes ACE to drop an additional 50 MW. What value
must ACE be returned to?
- ✔✔-100
•
What is considered a DCS event?
- ✔✔A loss of generation greater than or equal to 80% of your MSSC, multiple generator
losses are considered a single event if occurring within 60 seconds of each other.
•
When does the Contingency Reserve restoration period begin? How long do you have to restore
contingency reserve equal to your MSSC?
, - ✔✔At the end of the Disturbance control recovery period, 90 minutes
•
What makes up Operating reserves?
- ✔✔Regulating reserves (must be spinning), Contingency reserves (both spinning and
non-spinning)
•
How much of your contingency reserve should be spinning reserves?
- ✔✔50%
•
What is Regulating reserves used for?
- ✔✔Used to meet load forecasting errors, system tie-line and frequency regulation needs
•
What can be considered contingency reserve?
- ✔✔Generation, controllable load, coordinated adjustments to interchange schedules
•
For controllable load to be considered a contingency reserve what must it be?
- ✔✔must be available within 15 minutes
•
For generation to be considered spinning contingency reserve what must it be?
- ✔✔must be synchronized to the system and available within the DCS period
•
What is State Estimator?
- ✔✔A real time model of the current conditions of the power system
•
What is Contingency analysis? what does Contingency analysis rely on? How often should
Contingency analysis be ran?
- ✔✔evaluates potential outages and their impact on the remaining system, relies on State
Estimator values, should be ran every 30 minutes
•
what is the scan rate for ACE related data?
- ✔✔6 seconds
•
What must a BA experience to declare an EEA?
- ✔✔the BA is or expects to be unable to provide its customers load demands
•
Who request an EEA?
