EPRI CORE EXAM 2026 TEST QUESTIONS AND ANSWERS
GRADED A+
✔✔Angle stability limits are the result of?
A. High torque and power angles
B. The thermal capability of system equipment
C. A reactive power deficiency
D. All of the above - ✔✔A. High torque and power angles
✔✔If the resistance is ignored, the maximum theoretical MW flow across a
transmission line will occur at a power angle of:
A. 0 degrees
B. 45 degrees
C. 90 degrees
D. 180 degrees - ✔✔C. 90 degrees
✔✔If the resistance is ignored, the maximum theoretical Mvar flow across a
transmission line will occur at a power angle of:
A. 0 degrees
B. 45 degrees
C. 90 degrees
D. 180 degrees - ✔✔D. 180 degrees
✔✔200 MW is scheduled to flow from Bus "X" to Bus "Y". Transmission
line "A-B" has a 10% distribution factor for this schedule. How much of
the 200 MW schedule will flow on transmission line "A-B"?
A. 20 MW
B. 40 MW
C. 180 MW
D. 200 MW - ✔✔A. 20 MW
✔✔According to the load/frequency relationship, a 1% change in frequency
will lead to what approximate magnitude of load change in a typical
10,000 MW system?
A. 500 MW
B. 1000 MW
C. 200 MW
D. 50 MW - ✔✔C. 200 MW
✔✔A governor with a 0% droop is called:
A. Flat frequency control
B. Transient droop
C. A blocked governor
D. An isochronous governor - ✔✔D. An isochronous governor
,✔✔Steam turbine generators typically have better governor response than
hydro-electric generating units.
A. True
B. False - ✔✔B. False
✔✔A Balancing Authority's frequency bias setting is equal to:
A. The Balancing Authority's frequency response characteristic
(FRC)
B. The natural response of the Balancing Authority
C. The AGC system's bias value
D. All of the above - ✔✔D. All of the above
✔✔All of the following are modes of AGC EXCEPT:
A. Flat tie-line control
B. Isochronous control
C. Flat frequency control
D. Tie-line bias control - ✔✔B. Isochronous control
✔✔In which stage of a generator's response to a system disturbance is the
power flow supported primarily by the generator's excitation system?
A. Governor response stage
B. AGC stage
C. Electromagnetic energy stage
D. Inertial stage - ✔✔C. Electromagnetic energy stage
✔✔If system frequency were to run at 60.02 HZ for two consecutive hours,
how much positive time error would occur?
A. 2.0 seconds
B. 2.4 seconds
C. 1.0 second
D. 1.2 seconds - ✔✔B. 2.4 seconds
✔✔A Balancing Authority has a bias of -150 MW. Frequency falls 0.05 HZ
due to an external disturbance. How many MW would you expect this
Balancing Authority to provide to the disturbance?
A. -75
B. +75
C. -150
D. +150 - ✔✔B. +75
✔✔An isochronous governor has a droop setting of:
A. 5%
B. 0%
, C. 10%
D. 8% - ✔✔B. 0%
✔✔What element of the power system is typically most susceptible to damage
from prolonged operation at frequencies above or below 60 HZ?
A. Transformers greater than 300 MVA
B. Low pressure turbine stage blades
C. Synchronous motors
D. Induction motors - ✔✔B. Low pressure turbine stage blades
✔✔What is the Mvar production of a 50 Mvar shunt capacitor that is
energized at 90% of its nominal voltage?
A. 40.5
B. 45
C. 55.6
D. 61.7 - ✔✔A. 40.5
✔✔A 5% change in voltage will typically lead to what change in the total load
magnitude?
A. 2%
B. 3%
C. 5%
D. 10% - ✔✔B. 3%
✔✔A transformer can be overexcited if exposed to:
A. High voltage
B. Low frequency
C. High voltage and low frequency
D. All of the above - ✔✔D. All of the above
✔✔What is the approximate Mvar/Mile production for a 345 kV overhead
line?
A. 1/3
B. 3/4
C. 2.0
D. 5.0 - ✔✔B. 3/4
✔✔A 345 kV transmission line operates at various voltage levels throughout
the day. At which voltage level does the transmission line produce more
Mvar?
A. 345 kV
B. 340 kV
C. 350 kV
D. 360 kV - ✔✔D. 360 kV
GRADED A+
✔✔Angle stability limits are the result of?
A. High torque and power angles
B. The thermal capability of system equipment
C. A reactive power deficiency
D. All of the above - ✔✔A. High torque and power angles
✔✔If the resistance is ignored, the maximum theoretical MW flow across a
transmission line will occur at a power angle of:
A. 0 degrees
B. 45 degrees
C. 90 degrees
D. 180 degrees - ✔✔C. 90 degrees
✔✔If the resistance is ignored, the maximum theoretical Mvar flow across a
transmission line will occur at a power angle of:
A. 0 degrees
B. 45 degrees
C. 90 degrees
D. 180 degrees - ✔✔D. 180 degrees
✔✔200 MW is scheduled to flow from Bus "X" to Bus "Y". Transmission
line "A-B" has a 10% distribution factor for this schedule. How much of
the 200 MW schedule will flow on transmission line "A-B"?
A. 20 MW
B. 40 MW
C. 180 MW
D. 200 MW - ✔✔A. 20 MW
✔✔According to the load/frequency relationship, a 1% change in frequency
will lead to what approximate magnitude of load change in a typical
10,000 MW system?
A. 500 MW
B. 1000 MW
C. 200 MW
D. 50 MW - ✔✔C. 200 MW
✔✔A governor with a 0% droop is called:
A. Flat frequency control
B. Transient droop
C. A blocked governor
D. An isochronous governor - ✔✔D. An isochronous governor
,✔✔Steam turbine generators typically have better governor response than
hydro-electric generating units.
A. True
B. False - ✔✔B. False
✔✔A Balancing Authority's frequency bias setting is equal to:
A. The Balancing Authority's frequency response characteristic
(FRC)
B. The natural response of the Balancing Authority
C. The AGC system's bias value
D. All of the above - ✔✔D. All of the above
✔✔All of the following are modes of AGC EXCEPT:
A. Flat tie-line control
B. Isochronous control
C. Flat frequency control
D. Tie-line bias control - ✔✔B. Isochronous control
✔✔In which stage of a generator's response to a system disturbance is the
power flow supported primarily by the generator's excitation system?
A. Governor response stage
B. AGC stage
C. Electromagnetic energy stage
D. Inertial stage - ✔✔C. Electromagnetic energy stage
✔✔If system frequency were to run at 60.02 HZ for two consecutive hours,
how much positive time error would occur?
A. 2.0 seconds
B. 2.4 seconds
C. 1.0 second
D. 1.2 seconds - ✔✔B. 2.4 seconds
✔✔A Balancing Authority has a bias of -150 MW. Frequency falls 0.05 HZ
due to an external disturbance. How many MW would you expect this
Balancing Authority to provide to the disturbance?
A. -75
B. +75
C. -150
D. +150 - ✔✔B. +75
✔✔An isochronous governor has a droop setting of:
A. 5%
B. 0%
, C. 10%
D. 8% - ✔✔B. 0%
✔✔What element of the power system is typically most susceptible to damage
from prolonged operation at frequencies above or below 60 HZ?
A. Transformers greater than 300 MVA
B. Low pressure turbine stage blades
C. Synchronous motors
D. Induction motors - ✔✔B. Low pressure turbine stage blades
✔✔What is the Mvar production of a 50 Mvar shunt capacitor that is
energized at 90% of its nominal voltage?
A. 40.5
B. 45
C. 55.6
D. 61.7 - ✔✔A. 40.5
✔✔A 5% change in voltage will typically lead to what change in the total load
magnitude?
A. 2%
B. 3%
C. 5%
D. 10% - ✔✔B. 3%
✔✔A transformer can be overexcited if exposed to:
A. High voltage
B. Low frequency
C. High voltage and low frequency
D. All of the above - ✔✔D. All of the above
✔✔What is the approximate Mvar/Mile production for a 345 kV overhead
line?
A. 1/3
B. 3/4
C. 2.0
D. 5.0 - ✔✔B. 3/4
✔✔A 345 kV transmission line operates at various voltage levels throughout
the day. At which voltage level does the transmission line produce more
Mvar?
A. 345 kV
B. 340 kV
C. 350 kV
D. 360 kV - ✔✔D. 360 kV
