ELECTRIC UTILITY OPERATIONS
LADWP ELECTRIC STATION OPERATOR (CIRCUIT BREAKERS, DISCONNECTS,
TRANSFORMERS) EXAM QUESTIONS WITH ALREADY PASSED ANSWERS!!
2026/2027
A+
Complete Blueprint Coverage | Station Equipment Domains | Verified Rationales
A+ 5 100%
QUESTIONS VERIFIED EXAM DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
Circuit Breaker Types, Operation, and Maintenance
Disconnect Switches and Isolating Devices
Power Transformers: Principles, Cooling, and Protection
Switching Procedures, Safety Clearances, and Lockout/Tagout
Fault Conditions, Relay Protection, and Operational Troubleshooting
STUVIAACTUALEXAM
, CIRCUIT BREAKER TYPES, OPERATION, AND MAINTENANCE
A station operator is preparing to open a 230 kV SF6 circuit breaker under normal load. The breaker control
Q1 switch is turned to the OPEN position, but the breaker fails to open and the green light remains illuminated.
The most appropriate first action is to:
A. Immediately climb the structure and manually trip the breaker with the mechanical lever.
B. Verify control power, check for trip-coil continuity or blown fuses, and confirm interlock status before attempting further
operations.
C. Close the adjacent breaker to parallel the circuit and then force the original breaker open.
D. Declare the breaker failed and de-energize the entire bus without further investigation.
Correct Answer: B
Rationale:
Control-power loss, trip-coil failure, or interlock conditions are common reasons a breaker will not open. Manual mechanical
operation or forcing paralleling without diagnosis risks equipment damage and personnel injury.
During a routine inspection of an oil circuit breaker, the operator notes that the oil level is below the minimum
Q2 mark on the sight glass and the oil appears dark and carbonized. The correct operational response is to:
A. Continue normal switching because oil level does not affect interrupting capability.
B. Remove the breaker from service for oil replacement or filtration and internal inspection before further load-breaking
operations.
C. Add any available insulating oil without testing dielectric strength.
D. Operate the breaker only for closing operations and never for opening.
Correct Answer: B
Rationale:
Low or degraded oil reduces dielectric strength and arc-quenching ability. The breaker must be taken out of service for proper
maintenance rather than continued operation.
A vacuum circuit breaker has just interrupted a fault. The operator is reviewing the event record and notices
Q3 that the contact wear counter has reached the manufacturer's recommended limit. The appropriate action is
to:
A. Reset the counter and continue normal operation indefinitely.
B. Schedule contact inspection or replacement according to the manufacturer's maintenance interval and document the
finding.
C. Increase the trip setting so the breaker operates less frequently.
D. Replace the entire breaker immediately without further evaluation.
Correct Answer: B
Rationale:
Vacuum interrupter contacts have a finite life measured by the wear counter. Reaching the limit requires planned maintenance, not
indefinite continued use or arbitrary setting changes.
LADWP ELECTRIC STATION OPERATOR (CIRCUIT BREAKERS, DISCONNECTS,
TRANSFORMERS) EXAM QUESTIONS WITH ALREADY PASSED ANSWERS!!
2026/2027
A+
Complete Blueprint Coverage | Station Equipment Domains | Verified Rationales
A+ 5 100%
QUESTIONS VERIFIED EXAM DOMAINS COVERED RATIONALES INCLUDED
CATEGORIES
Circuit Breaker Types, Operation, and Maintenance
Disconnect Switches and Isolating Devices
Power Transformers: Principles, Cooling, and Protection
Switching Procedures, Safety Clearances, and Lockout/Tagout
Fault Conditions, Relay Protection, and Operational Troubleshooting
STUVIAACTUALEXAM
, CIRCUIT BREAKER TYPES, OPERATION, AND MAINTENANCE
A station operator is preparing to open a 230 kV SF6 circuit breaker under normal load. The breaker control
Q1 switch is turned to the OPEN position, but the breaker fails to open and the green light remains illuminated.
The most appropriate first action is to:
A. Immediately climb the structure and manually trip the breaker with the mechanical lever.
B. Verify control power, check for trip-coil continuity or blown fuses, and confirm interlock status before attempting further
operations.
C. Close the adjacent breaker to parallel the circuit and then force the original breaker open.
D. Declare the breaker failed and de-energize the entire bus without further investigation.
Correct Answer: B
Rationale:
Control-power loss, trip-coil failure, or interlock conditions are common reasons a breaker will not open. Manual mechanical
operation or forcing paralleling without diagnosis risks equipment damage and personnel injury.
During a routine inspection of an oil circuit breaker, the operator notes that the oil level is below the minimum
Q2 mark on the sight glass and the oil appears dark and carbonized. The correct operational response is to:
A. Continue normal switching because oil level does not affect interrupting capability.
B. Remove the breaker from service for oil replacement or filtration and internal inspection before further load-breaking
operations.
C. Add any available insulating oil without testing dielectric strength.
D. Operate the breaker only for closing operations and never for opening.
Correct Answer: B
Rationale:
Low or degraded oil reduces dielectric strength and arc-quenching ability. The breaker must be taken out of service for proper
maintenance rather than continued operation.
A vacuum circuit breaker has just interrupted a fault. The operator is reviewing the event record and notices
Q3 that the contact wear counter has reached the manufacturer's recommended limit. The appropriate action is
to:
A. Reset the counter and continue normal operation indefinitely.
B. Schedule contact inspection or replacement according to the manufacturer's maintenance interval and document the
finding.
C. Increase the trip setting so the breaker operates less frequently.
D. Replace the entire breaker immediately without further evaluation.
Correct Answer: B
Rationale:
Vacuum interrupter contacts have a finite life measured by the wear counter. Reaching the limit requires planned maintenance, not
indefinite continued use or arbitrary setting changes.
