LADWP Electric Station Operator Exam Actual
Exam 2026/2027 with Detailed Rationales |
Complete Exam-Style Questions | Pass
Guaranteed – A+ Graded
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SECTION 1: POWER SYSTEM FUNDAMENTALS Q1 – Q10
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Question 1 of 50
A 230kV substation transformer bank is loaded to 80 MVA at a 0.80 power factor.
Calculate the reactive power (MVAR) demanded by this load.
. 64.0 MVAR
A
B. 36.0 MVAR
C. 48.0 MVAR ✓ CORRECT
D. 80.0 MVAR
orrect Answer: C
C
Rationale: Reactive power is calculated using the formula MVAR = MVA × sin(θ), where
θ is the angle whose cosine is the power factor; an 80 MVA load at 0.80 PF yields 48
MVAR. Selecting 64 MVAR incorrectly assumes this value represents reactive power
when it actually represents the real power (MW) component of the apparent power
triangle. Always resolve the power triangle carefully to distinguish between real,
reactive, and apparent power under varying load conditions.
Question 2 of 50
,A generating station operator notices system frequency has dropped to 59.85 Hz. The
governor response on a 500 MW generator adjusts output to restore the 60 Hz standard.
Determine the generator's operational priority in this scenario.
. Maintain voltage output at the expense of frequency
A
B. Decrease prime mover torque to prevent over-excitation
C. Increase prime mover torque to arrest the frequency decline ✓ CORRECT
D. Increase excitation current to stabilize the grid
orrect Answer: C
C
Rationale: Arresting a frequency decline requires increasing the mechanical power input
to the generator, which directly increases prime mover torque and restores the
machine's rotational speed to synchronous speed. Decreasing prime mover torque
would exacerbate the frequency drop, while adjusting excitation only controls voltage
and reactive power, not frequency. Remember the governor control loop: frequency
dictates mechanical torque (real power), while excitation dictates voltage (reactive
power).
Question 3 of 50
A technician is analyzing a balanced three-phase wye-connected system where the
line-to-line voltage is measured at 13.8 kV. Identify the line-to-neutral voltage magnitude
for this system.
. 23.9 kV
A
B. 13.8 kV
C. 8.0 kV
D. 7.97 kV ✓ CORRECT
, orrect Answer: D
C
Rationale: In a wye-connected system, the line-to-neutral voltage equals the line-to-line
voltage divided by the square root of three, making 13.8 kV divided by 1.732
approximately 7.97 kV. Assuming 13.8 kV is the line-to-neutral voltage is a common
error that ignores the 30-degree phase shift and magnitude difference inherent to
three-phase phasor math. Memorize the core three-phase relationships: wye
connections have V_LN = V_LL / √3, while delta connections have V_LN = V_LL.
Question 4 of 50
During a peak loading condition, a 230 kV bus voltage drops to 218 kV. Operators must
apply capacitor bank switching to improve the voltage profile. Explain the primary
electrical effect of energizing the capacitor bank.
. Absorbs reactive power to stabilize the voltage
A
B. Decreases line current by increasing power factor lag
C. Increases system impedance to limit fault current
D. Supplies reactive power to reduce the reactive voltage drop ✓ CORRECT
orrect Answer: D
C
Rationale: Energizing a capacitor bank injects reactive power (MVARs) into the system,
which offsets the inductive reactive power demand and reduces the reactive voltage
drop along the transmission line. Absorbing reactive power would describe an inductor
or reactor, which would further pull the voltage down rather than support it. On the
LADWP system, capacitor bank switching is the primary method operators use for local
voltage support during heavy load conditions.
Question 5 of 50
, An operator reviews protection settings for a 34.5 kV distribution feeder and notes an
intentional time delay on the overcurrent relay. State the primary purpose of this
deliberate time delay.
. Ensures the breaker operates faster during severe faults
A
B. Allows downstream devices to clear faults first via coordination ✓ CORRECT
C. Provides time for the breaker to rebuild its dielectric strength
D. Prevents nuisance tripping during transient inrush currents
orrect Answer: B
C
Rationale: Time delays on overcurrent relays are fundamentally designed for protective
coordination, ensuring that the relay closest to the fault operates first to isolate the
problem without tripping upstream devices. Preventing nuisance tripping during inrush
is typically handled by harmonic restraint or a long initial time delay, but standard time
delays exist specifically for coordination grading margins. Always map the time-current
curves in your switching plan to understand which device operates first during a fault.
Question 6 of 50
A station operator monitors a 500 kV transmission line and observes that the current
magnitude is 1500 A while the voltage is 500 kV line-to-line. Calculate the approximate
three-phase apparent power flowing through this line.
. 750 MVA
A
B. 433 MVA
C. 1500 MVA
D. 1300 MVA ✓ CORRECT
Correct Answer: D
Exam 2026/2027 with Detailed Rationales |
Complete Exam-Style Questions | Pass
Guaranteed – A+ Graded
═════════════════════════════════════
═
SECTION 1: POWER SYSTEM FUNDAMENTALS Q1 – Q10
══════════════════════════════════════
Question 1 of 50
A 230kV substation transformer bank is loaded to 80 MVA at a 0.80 power factor.
Calculate the reactive power (MVAR) demanded by this load.
. 64.0 MVAR
A
B. 36.0 MVAR
C. 48.0 MVAR ✓ CORRECT
D. 80.0 MVAR
orrect Answer: C
C
Rationale: Reactive power is calculated using the formula MVAR = MVA × sin(θ), where
θ is the angle whose cosine is the power factor; an 80 MVA load at 0.80 PF yields 48
MVAR. Selecting 64 MVAR incorrectly assumes this value represents reactive power
when it actually represents the real power (MW) component of the apparent power
triangle. Always resolve the power triangle carefully to distinguish between real,
reactive, and apparent power under varying load conditions.
Question 2 of 50
,A generating station operator notices system frequency has dropped to 59.85 Hz. The
governor response on a 500 MW generator adjusts output to restore the 60 Hz standard.
Determine the generator's operational priority in this scenario.
. Maintain voltage output at the expense of frequency
A
B. Decrease prime mover torque to prevent over-excitation
C. Increase prime mover torque to arrest the frequency decline ✓ CORRECT
D. Increase excitation current to stabilize the grid
orrect Answer: C
C
Rationale: Arresting a frequency decline requires increasing the mechanical power input
to the generator, which directly increases prime mover torque and restores the
machine's rotational speed to synchronous speed. Decreasing prime mover torque
would exacerbate the frequency drop, while adjusting excitation only controls voltage
and reactive power, not frequency. Remember the governor control loop: frequency
dictates mechanical torque (real power), while excitation dictates voltage (reactive
power).
Question 3 of 50
A technician is analyzing a balanced three-phase wye-connected system where the
line-to-line voltage is measured at 13.8 kV. Identify the line-to-neutral voltage magnitude
for this system.
. 23.9 kV
A
B. 13.8 kV
C. 8.0 kV
D. 7.97 kV ✓ CORRECT
, orrect Answer: D
C
Rationale: In a wye-connected system, the line-to-neutral voltage equals the line-to-line
voltage divided by the square root of three, making 13.8 kV divided by 1.732
approximately 7.97 kV. Assuming 13.8 kV is the line-to-neutral voltage is a common
error that ignores the 30-degree phase shift and magnitude difference inherent to
three-phase phasor math. Memorize the core three-phase relationships: wye
connections have V_LN = V_LL / √3, while delta connections have V_LN = V_LL.
Question 4 of 50
During a peak loading condition, a 230 kV bus voltage drops to 218 kV. Operators must
apply capacitor bank switching to improve the voltage profile. Explain the primary
electrical effect of energizing the capacitor bank.
. Absorbs reactive power to stabilize the voltage
A
B. Decreases line current by increasing power factor lag
C. Increases system impedance to limit fault current
D. Supplies reactive power to reduce the reactive voltage drop ✓ CORRECT
orrect Answer: D
C
Rationale: Energizing a capacitor bank injects reactive power (MVARs) into the system,
which offsets the inductive reactive power demand and reduces the reactive voltage
drop along the transmission line. Absorbing reactive power would describe an inductor
or reactor, which would further pull the voltage down rather than support it. On the
LADWP system, capacitor bank switching is the primary method operators use for local
voltage support during heavy load conditions.
Question 5 of 50
, An operator reviews protection settings for a 34.5 kV distribution feeder and notes an
intentional time delay on the overcurrent relay. State the primary purpose of this
deliberate time delay.
. Ensures the breaker operates faster during severe faults
A
B. Allows downstream devices to clear faults first via coordination ✓ CORRECT
C. Provides time for the breaker to rebuild its dielectric strength
D. Prevents nuisance tripping during transient inrush currents
orrect Answer: B
C
Rationale: Time delays on overcurrent relays are fundamentally designed for protective
coordination, ensuring that the relay closest to the fault operates first to isolate the
problem without tripping upstream devices. Preventing nuisance tripping during inrush
is typically handled by harmonic restraint or a long initial time delay, but standard time
delays exist specifically for coordination grading margins. Always map the time-current
curves in your switching plan to understand which device operates first during a fault.
Question 6 of 50
A station operator monitors a 500 kV transmission line and observes that the current
magnitude is 1500 A while the voltage is 500 kV line-to-line. Calculate the approximate
three-phase apparent power flowing through this line.
. 750 MVA
A
B. 433 MVA
C. 1500 MVA
D. 1300 MVA ✓ CORRECT
Correct Answer: D
