LADWP ELECTRIC STATION OPERATOR ACTUAL EXAM 2026/2027
PRACTICE QUESTIONS AND A NEW UPDATED STUDY GUIDE
COMPLETE ACCURATE TEST APPROVED QUESTIONS AND CORRECT
VERIFIED SOLUTIONS WITH DETAILED RATIONALES (100% CORRECT
VERIFIED ANSWERS) CURRENTLY UPDATED VERSION 2026 EDITION
|GUARANTEED SUCCESS A+ |BRAND NEW!
1. A 500 kV transmission line experiences a sudden loss of load. The
primary protective action should be to:
A) Increase excitation to the generator
B) Trip the line circuit breaker immediately
C) Manually reduce generator field current
D) Bypass the transformer differential relay
Correct Answer: B – Trip the line circuit breaker immediately
Rationale: Loss of load on an EHV line can cause overvoltage and
instability. Immediate tripping of the line breaker isolates the faulted
section and prevents damage to equipment. Manual adjustments (A or
C) are too slow; bypassing relay (D) disables protection.
2. Which condition indicates a synchronous generator is losing
synchronism with the grid?
A) Constant terminal voltage
B) Slip frequency oscillations in active power
C) Unity power factor operation
D) Steady field current
Correct Answer: B – Slip frequency oscillations in active power
Rationale: Loss of synchronism (pole slipping) causes measurable
oscillations in real power and current at a slip frequency. Constant
,voltage (A) and steady field current (D) suggest stability; unity PF (C) is
normal under certain loads.
3. A station operator notices the differential relay on a 13.8 kV bus has
operated. What is the most likely cause?
A) External phase-to-ground fault
B) Current transformer (CT) saturation during external fault
C) Internal bus fault
D) Over excitation of transformer
Correct Answer: C – Internal bus fault
Rationale: Bus differential relays compare currents entering and leaving
a bus zone. Operation indicates an internal fault within the protected
zone. CT saturation (B) can cause disoperation but is less likely than an
actual fault.
4. In a gas-insulated substation (GIS), SF6 gas pressure drops to 80% of
nominal. The operator should FIRST:
A) Immediately de-energize the bus
B) Top up SF6 from a cylinder
C) Check for leaks while monitoring load
D) Bypass the low-pressure interlock
Correct Answer: C – Check for leaks while monitoring load
Rationale: Moderate pressure drop allows time for leak detection and
refill without immediate outage. De-energizing (A) is for severe drops;
topping up without locating leak (B) ignores safety; bypassing interlock
(D) disables critical protection.
5. What does an increasing trend in transformer dissolved gas analysis
(DGA) for acetylene indicate?
A) Normal paper insulation aging
B) Overloading within nameplate rating
,C) High-energy arcing fault
D) Moisture ingress
Correct Answer: C – High-energy arcing fault
*Rationale: Acetylene in oil is produced only by high-temperature arcs.
Normal aging (A) produces CO/CO2; overloading (B) yields ethylene;
moisture (D) does not generate acetylene. *
6. A 230 kV breaker fails to trip on a protection command. The
operator’s next action should be:
A) Manually open the breaker locally
B) Initiate breaker failure protection to trip upstream breakers
C) Close the breaker again and retry
D) Reduce load on the affected line
Correct Answer: B – Initiate breaker failure protection to trip upstream
breakers
Rationale: Breaker failure protection (BFP) automatically clears the
fault by removing all sources feeding the failed breaker. Manual
intervention (A) is too slow; reclosing (C) is dangerous; reducing load
(D) does not clear the fault.
7. Which meter reading best indicates a synchronous motor is operating
with leading power factor?
A) Field current higher than rated
B) Armature current minimum
C) Armature current higher than rated with lagging vats
D) Armature current higher than rated with leading vats
Correct Answer: D – Armature current higher than rated with leading
vats
Rationale: Leading PF (overexcited motor) draws increased armature
current and supplies reactive power (leading vats). Minimum current
, (B) occurs at unity PF; high field current (A) alone does not confirm
leading PF.
8. A sudden drop in station service voltage is accompanied by a loud
bang and smoke from a 4160 V switchgear cubicle. First priority action:
A) Call the shift supervisor
B) Try to reset the breaker remotely
C) Evacuate the area and de-energize if safe
D) Use a fire extinguisher on the smoke
Correct Answer: C – Evacuate the area and de-energize if safe
Rationale: Personnel safety is paramount. Smoke and bang indicate
possible arc flash or fire. Evacuation followed by remote de-
energization prevents injury. Calling supervisor (A) wastes time;
resetting (B) or fighting fire without power off (D) risks electrocution.
9. What does a Buchholz relay on an oil-filled transformer detect?
A) Winding temperature
B) Low oil level only
C) Incipient faults and gas accumulation
D) Overvoltage
Correct Answer: C – Incipient faults and gas accumulation
Rationale: Buchholz relay detects gas produced by partial discharges or
low-level arcing, and also oil surge from major faults. Temperature (A)
is monitored by RTDs; low oil (B) is part but not main; overvoltage (D)
is unrelated.
10. During synchronization of a generator to the grid, the synchro scope
rotates slowly in the “fast” direction. The operator should:
A) Increase generator speed slightly
B) Decrease generator speed slightly
PRACTICE QUESTIONS AND A NEW UPDATED STUDY GUIDE
COMPLETE ACCURATE TEST APPROVED QUESTIONS AND CORRECT
VERIFIED SOLUTIONS WITH DETAILED RATIONALES (100% CORRECT
VERIFIED ANSWERS) CURRENTLY UPDATED VERSION 2026 EDITION
|GUARANTEED SUCCESS A+ |BRAND NEW!
1. A 500 kV transmission line experiences a sudden loss of load. The
primary protective action should be to:
A) Increase excitation to the generator
B) Trip the line circuit breaker immediately
C) Manually reduce generator field current
D) Bypass the transformer differential relay
Correct Answer: B – Trip the line circuit breaker immediately
Rationale: Loss of load on an EHV line can cause overvoltage and
instability. Immediate tripping of the line breaker isolates the faulted
section and prevents damage to equipment. Manual adjustments (A or
C) are too slow; bypassing relay (D) disables protection.
2. Which condition indicates a synchronous generator is losing
synchronism with the grid?
A) Constant terminal voltage
B) Slip frequency oscillations in active power
C) Unity power factor operation
D) Steady field current
Correct Answer: B – Slip frequency oscillations in active power
Rationale: Loss of synchronism (pole slipping) causes measurable
oscillations in real power and current at a slip frequency. Constant
,voltage (A) and steady field current (D) suggest stability; unity PF (C) is
normal under certain loads.
3. A station operator notices the differential relay on a 13.8 kV bus has
operated. What is the most likely cause?
A) External phase-to-ground fault
B) Current transformer (CT) saturation during external fault
C) Internal bus fault
D) Over excitation of transformer
Correct Answer: C – Internal bus fault
Rationale: Bus differential relays compare currents entering and leaving
a bus zone. Operation indicates an internal fault within the protected
zone. CT saturation (B) can cause disoperation but is less likely than an
actual fault.
4. In a gas-insulated substation (GIS), SF6 gas pressure drops to 80% of
nominal. The operator should FIRST:
A) Immediately de-energize the bus
B) Top up SF6 from a cylinder
C) Check for leaks while monitoring load
D) Bypass the low-pressure interlock
Correct Answer: C – Check for leaks while monitoring load
Rationale: Moderate pressure drop allows time for leak detection and
refill without immediate outage. De-energizing (A) is for severe drops;
topping up without locating leak (B) ignores safety; bypassing interlock
(D) disables critical protection.
5. What does an increasing trend in transformer dissolved gas analysis
(DGA) for acetylene indicate?
A) Normal paper insulation aging
B) Overloading within nameplate rating
,C) High-energy arcing fault
D) Moisture ingress
Correct Answer: C – High-energy arcing fault
*Rationale: Acetylene in oil is produced only by high-temperature arcs.
Normal aging (A) produces CO/CO2; overloading (B) yields ethylene;
moisture (D) does not generate acetylene. *
6. A 230 kV breaker fails to trip on a protection command. The
operator’s next action should be:
A) Manually open the breaker locally
B) Initiate breaker failure protection to trip upstream breakers
C) Close the breaker again and retry
D) Reduce load on the affected line
Correct Answer: B – Initiate breaker failure protection to trip upstream
breakers
Rationale: Breaker failure protection (BFP) automatically clears the
fault by removing all sources feeding the failed breaker. Manual
intervention (A) is too slow; reclosing (C) is dangerous; reducing load
(D) does not clear the fault.
7. Which meter reading best indicates a synchronous motor is operating
with leading power factor?
A) Field current higher than rated
B) Armature current minimum
C) Armature current higher than rated with lagging vats
D) Armature current higher than rated with leading vats
Correct Answer: D – Armature current higher than rated with leading
vats
Rationale: Leading PF (overexcited motor) draws increased armature
current and supplies reactive power (leading vats). Minimum current
, (B) occurs at unity PF; high field current (A) alone does not confirm
leading PF.
8. A sudden drop in station service voltage is accompanied by a loud
bang and smoke from a 4160 V switchgear cubicle. First priority action:
A) Call the shift supervisor
B) Try to reset the breaker remotely
C) Evacuate the area and de-energize if safe
D) Use a fire extinguisher on the smoke
Correct Answer: C – Evacuate the area and de-energize if safe
Rationale: Personnel safety is paramount. Smoke and bang indicate
possible arc flash or fire. Evacuation followed by remote de-
energization prevents injury. Calling supervisor (A) wastes time;
resetting (B) or fighting fire without power off (D) risks electrocution.
9. What does a Buchholz relay on an oil-filled transformer detect?
A) Winding temperature
B) Low oil level only
C) Incipient faults and gas accumulation
D) Overvoltage
Correct Answer: C – Incipient faults and gas accumulation
Rationale: Buchholz relay detects gas produced by partial discharges or
low-level arcing, and also oil surge from major faults. Temperature (A)
is monitored by RTDs; low oil (B) is part but not main; overvoltage (D)
is unrelated.
10. During synchronization of a generator to the grid, the synchro scope
rotates slowly in the “fast” direction. The operator should:
A) Increase generator speed slightly
B) Decrease generator speed slightly
