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WorksheetsPASGT Lec Midterm Quiz 2
Total questions: 25
Worksheet time: 19mins
How do emergency stop (E-stop) controls contribute to turbine safety?
They accelerate turbine deceleration to synchronize with exhaust pressure.
They provide immediate shutdown capability in hazardous conditions.
They enhance combustion efficiency during startup.
They regulate vibration damping mechanisms during load changes.
Which preventive measure reduces the risk of failed startup caused by interlock malfunction?
Bypassing the interlock to allow manual startup which ensures that the engine can actually be operated.
Increasing fuel pressure above normal thresholds.
Conducting regular calibration and verification of interlock sensors.
Running the starter motor at higher speeds than recommended.
Why is it important to confirm “ready” status on fire suppression systems before introducing fuel?
To maintain correct lubrication film thickness during acceleration
To improve sensor accuracy in detecting vibration
To increase exhaust gas velocity during startup which avoids overheating in the combustion chamber
To ensure immediate fire response capability if ignition leads to flameout
What does a “ready” signal from the lube oil system interlock indicate?
The turbine can now operate under partial load conditions.
Oil pressure and temperature are sufficient for safe rotor operation.
Exhaust temperature is below ignition threshold levels.
The compressor speed is adequate for fuel injection.
Why is continuous communication with the control room essential during turbine preparation?
It ensures coordinated responses to system alarms.
It increases air intake pressure for optimal combustion.
It improves lubrication film strength before acceleration.
It maintains pressure differential in the cooling circuit.
Why is verifying the operation of pre-lube pumps crucial before rotating the turbine rotor?
It ensures that oil seals are pressurized before the turbine is shut down which prevents overheating.
It prevents air pockets from forming in the turbine combustion chamber.
It verifies that the cooling system can maintain stable thermal conditions.
It confirms that all lubrication components are functioning before ignition.
During preparation, what would the most likely consequence be if air is not fully purged from the fuel system?
The turbine will start but operate with reduced exhaust velocity.
The ignition may fail due to inconsistent fuel delivery during startup.
The lubrication system will overheat due to incomplete oil flow.
The air intake system will draw in unfiltered atmospheric gases.
Which situation best illustrates the function of a pressure interlock in a marine gas turbine system?
Preventing fuel introduction if lube oil pressure is below safe levels.
Reducing exhaust backpressure when turbine speed exceeds the set limit.
Halting the air intake fan if vibration exceeds acceptable parameters.
Shutting down the generator if voltage fluctuations are detected.
Why must cooling system flow indicators be checked before turbine startup?
To ensure the turbine reaches maximum power output immediately and ensure efficiency.
To guarantee proper alignment of rotor bearings and seals.
To verify that the fuel system has adequate pressure for combustion.
To confirm sufficient thermal regulation and avoid overtemperature trips.
What is the primary reason for confirming the readiness of fire suppression systems before introducing fuel?
It ensures that ignition occurs only at maximum turbine speed.
It guarantees compliance with maintenance scheduling requirements.
It prepares the system for rapid response in case of combustion anomalies.
It prevents air ingestion during turbine acceleration.
A gas turbine trips automatically during startup because the vibration level exceeds the preset limit. What does this indicate about the interlock system?
It is malfunctioning and failed to detect the pressure variation.
It is functioning correctly by preventing potential mechanical failure.
It is bypassed and allowing the turbine to start under unsafe conditions.
It is incorrectly calibrated to allow excessive rotational speed.
Which action is most critical when a cooling system pressure differential is outside acceptable limits before startup?
Proceed with startup but limit turbine load to 50%.
Bypass the cooling interlock and monitor exhaust temperature closely.
Abort the start sequence and investigate pump or flow restrictions.
Continue operation but increase lube oil flow to compensate.
Why is proper calibration of temperature, pressure, and vibration sensors essential during preparation?
It verifies the accuracy of real-time data for safety and trip decisions.
It ensures the control system can compensate for external weather conditions.
It allows the turbine to operate beyond its rated power limits.
It reduces the need for manual checks and maintenance schedules.
What could result if intake dampers are not fully open during turbine startup?
Combustion will be delayed due to low fuel pressure.
Air starvation may lead to incomplete combustion and temperature spikes.
The exhaust system will accumulate excessive backpressure due to insufficient air intake.
Lube oil flow will exceed the rated pump capacity.
Why must emergency shutdown (E-stop) controls be verified before starting the turbine?
They regulate the load-sharing system during propulsion changeover.
They calibrate the speed governor to match operating conditions.
They ensure immediate shutdown capability if unsafe conditions occur.
They allow automatic restart in case of sensor malfunction making it safer to operate.
A turbine is prevented from starting because the fuel valve remains closed. Which interlock is most likely responsible?
Start interlock related to minimum oil pressure.
Vibration interlock associated with rotor imbalance.
Temperature interlock linked to exhaust gas temperature.
Speed interlock requiring minimum compressor speed.
What is the most probable consequence of starting a gas turbine without confirming lube oil pressure?
Uncontrolled acceleration due to excessive combustion energy.
Rapid bearing wear and possible mechanical seizure of the rotor.
Overheating of combustion chambers due to air starvation.
Activation of the fire suppression system due to incomplete ignition.
How do start interlocks contribute to safe turbine operation?
They delay fuel introduction until critical startup parameters are satisfied.
They increase turbine RPM beyond normal startup limits.
They prevent cooling system pumps from operating during startup to aid in warming-up the combustion chamber.
They synchronize turbine output with the ship’s main generator.
Why is it necessary to inspect intake filters and silencers before startup?
It ensures smooth fuel injection and atomization during ignition.
It optimizes exhaust gas velocity for efficient turbine acceleration during startup.
It prevents foreign object ingestion that could cause compressor damage.
It reduces the requirement for vibration damping mechanisms.
What action should be taken if the turbine fails to start due to a low lube oil pressure alarm?
Bypass the alarm to initiate emergency operation to avoid unnecessary delays.
Reduce the starting motor speed to allow oil circulation.
Increase fuel pressure to improve combustion stability.
Inspect pumps, filters, and oil supply systems for faults before restarting.
Why must the control panel undergo a diagnostic check prior to turbine ignition?
To verify operational readiness of control logic, alarms, and trip functions.
To synchronize generator frequency with ship electrical systems.
To ensure maximum power output during the acceleration phase and ensure efficiency.
To purge the combustion chamber before ignition begins.
If an overtemperature alarm occurs immediately after startup, what is the most likely root cause?
Incomplete purge of the fuel system before ignition.
Low lube oil pressure causing bearing overheating.
Cooling system malfunction leading to insufficient heat removal.
Intake air filters producing excessive pressure drop.
Which of the following illustrates proper compliance with Safe Working Practices during turbine preparation?
Starting the turbine immediately after inspection which confirms system verification.
Conducting lock-out/tag-out procedures before maintenance activities.
Operating the turbine with minor sensor faults if backup alarms are active.
Bypassing fire suppression systems during diagnostic tests.
What is the main reason for continuously monitoring vibration levels during turbine startup?
To ensure proper alignment between the turbine and reduction gearbox.
To identify and eliminate fuel pressure fluctuations caused by rapid combustion.
To verify lubrication viscosity and flow distribution.
To prevent excessive thermal stress on the exhaust system.
How do interlocks improve overall system reliability in marine gas turbines?
By reducing fuel consumption during acceleration phases which increases efficiency.
By automatically preventing operations that could result in equipment damage.
By enabling the turbine to bypass trip conditions for emergency operation.
By lowering exhaust emissions during low-load conditions.
