Turbine Control System Lecture Notes Review

A series of flashcards designed to help review key concepts and mechanisms related to turbine control systems for exam preparation.

What are the three main functions of the control oil system in a turbine?

1. High Pressure oil as a power supply, 2. Auto stop oil for emergency trip signal, 3. Emergency oil for protective devices.

What happens when the turbine speed reaches 110% of the rated speed?

The overspeed trip mechanism activates to stop all steam flow into the turbine.

Explain the function of the governing valve servomotor.

It controls the pressure of GV control oil according to electrical control signals and adjusts the position of the valve through relay movements.

What does the low vacuum trip device do?

It shuts down the turbine when exhaust pressure rises above a preset value.

When is the turbine emergency trip button used?

To manually trip the turbine and open the trip solenoid valve.

How does the auto stop oil system function in the case of an overspeed trip?

The overspeed trip weight moves out, opening the overspeed relay and draining the emergency oil, which leads to a stop in oil flow.

What is the purpose of the test lever in the emergency trip mechanism?

To lock the emergency device for testing the protective device under normal turbine operation without triggering an actual trip.

What is the role of the EH converter in the turbine control system?

To establish common control oil pressure signals for each main stop valve servomotor and position both valves simultaneously during acceleration.

Describe the construction and function of the torque motor in the electro-hydraulic converter.

It converts a d-c input current into a mechanical force to actuate the governing valve.

What is an important maintenance step for the governing valve concerning lubrication?

Regularly injecting grease into the sliding surfaces to prevent sticking.