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Steam Turbines Trivia Quiz

Most of this quiz is related to condensing steam turbines. Enjoy the trip.

A multiple-choice quiz by meremaleaus. Estimated time: 5 mins.

Author
meremaleaus

Time
5 mins

Type
Multiple Choice

Quiz #
308,252

Updated
Dec 03 21

# Qns
10

Difficulty
Tough

Avg Score
6 / 10

Plays
460

One at a Time - Single Page - Timed Game

Question 1 of 10

1. What turbine trip is designed to occur at 10% above normal operation? Hint

Out of phase trip.

High vibration trip.

Under frequency trip.

Overspeed trip.

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Question 2 of 10

2. What is the purpose of the thrust wear down, or low thrust oil pressure trip? Hint

To allow correct flow of oil to the rotor bearings.

To prevent excessive axial movement of the rotor.

To protect the labyrinth glands.

Stop white metal bearing from wearing.

NEXT>

Question 3 of 10

3. What causes the emergency steam trip valve to close? Hint

Spring pressure.

Loss of excitation.

Tripping oil pressure.

Negative phase sequence.

NEXT>

Question 4 of 10

4. What keeps the emergency steam trip valve to remain open? Hint

Tripping oil pressure.

Governor control oil pressure.

Stephensons link lever.

Thrust wear down limit.

NEXT>

Question 5 of 10

5. During a full load rejection test, what should occur? Hint

The turbine should trip to protect against blade tip turbulance.

Spring pressure holding the trip valve open will slam the trip valve shut.

The overspeed bolt will activate which trips the turbine.

The governor valve should control the speed of the turbine and not trip.

NEXT>

Question 6 of 10

6. What is the purpose of the low vacuum trip on a condensing turbine? Hint

To stop the turbine casing getting too hot.

To protect the mechanical integrity of the unit.

To protect the rupture disc from releasing steam to atmosphere.

To prevent live steam escaping from the sealing glands.

NEXT>

Question 7 of 10

7. The rotor turning gear trips on high amps just prior to a turbine run up. What has caused this? Hint

Field excitation has closed causing reststance in the alternator.

Low oil to the main turbine bearings causing the white metal surfaces to scrub.

Over heating and the labyrinth glands are touching, causing the rotor to jam up.

Steam is passing through and the rotor has begun turning.

NEXT>

Question 8 of 10

8. Your turbine has two critical speeds, during run up how do you manage these? Hint

Once increased vibration is noticed trip the turbine.

Lower the boiler pressure to reduce the impact of higher pressure steam.

Ignore the vibration as it will decrease once up to speed.

Momentarily push through these speeds to minimise vibration.

NEXT>

Question 9 of 10

9. What device manages the safe shutdown of the unit electrical breakers and excitation system? Hint

The turbine trip solinoid.

The burner management system.

The emergency trip lever.

The master trip relay.

NEXT>

Question 10 of 10

10. You have lost your boiler, it is not a range boiler. What do you do to manage the turbine? Hint

Trip the turbine immediately.

Reduce load to give you time to regain your boiler.

Start the main air ejector to protect the vacuum.

Close all bled steam valves to conserve steam.

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Quiz Answer Key and Fun Facts

1. What turbine trip is designed to occur at 10% above normal operation?

Answer: Overspeed trip.

The Australian electrical system runs at 50 cycles per second, therefore the turbine operating speed will be 3000 rpm. Taking into consideration any electrical grid fluctuations, the over speed trip is safely set above any such acceptable fluctuations at 3300 rpm.

2. What is the purpose of the thrust wear down, or low thrust oil pressure trip?

Answer: To prevent excessive axial movement of the rotor.

With the steam flow moving in parallel with the rotor, this causes axial thrust in that direction. The trip is designed to function before any moving parts make contact.

3. What causes the emergency steam trip valve to close?

Answer: Spring pressure.

Although there are many reasons why the trip valve would operate, it is the spring tension which actually closes the trip valve.

4. What keeps the emergency steam trip valve to remain open?

Answer: Tripping oil pressure.

Commonly known as tripping oil, this oil pressure remains in operation unless there is a cause to trip. Once a trip situation occurs, the tripping oil will be dumped and the emergency steam trip valve will shut.

5. During a full load rejection test, what should occur?

Answer: The governor valve should control the speed of the turbine and not trip.

Generally an annual test, the full load rejection test should prove the governor valve will maintain turbine speed regardless of load.

6. What is the purpose of the low vacuum trip on a condensing turbine?

Answer: To protect the mechanical integrity of the unit.

The condenser is not designed to hold a pressure and as such must be prevented from any positive pressure above atmospheric. Often rupture discs are fitted as a mechanical prevention against any pressure surge.

7. The rotor turning gear trips on high amps just prior to a turbine run up. What has caused this?

Answer: Over heating and the labyrinth glands are touching, causing the rotor to jam up.

If the steam passes through the governor valve prior to a run up, this can cause the rotor to overheat and expand. This expansion will eventually cause the gland sealing labyrinth ring tips to make contact with the non moving section and cause resistance. The turning gear will not be able to continue turning the rotor as this resistance increases.

8. Your turbine has two critical speeds, during run up how do you manage these?

Answer: Momentarily push through these speeds to minimise vibration.

Turbine rotors and steam blading have their own natural frequency and these are noticed during the run up phase. They are called critical speeds where vibration increases, time spent in these speed ranges should be minimized.

9. What device manages the safe shutdown of the unit electrical breakers and excitation system?

Answer: The master trip relay.

There are several reasons why a turbine protection trip will occur. To manage the electrical side of the turbine, the master trip relay will cause the turbine to disconnect from the electrical circuits.

10. You have lost your boiler, it is not a range boiler. What do you do to manage the turbine?

Answer: Reduce load to give you time to regain your boiler.

If conditions are right, and the operator is quick enough, a boiler recovery is possible without the need to shut down the turbine.

Source: Author meremaleaus

This quiz was reviewed by FunTrivia editor crisw before going online.
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