Question

Steam turbines are governed by the following methods :
1. Throttle governing
2. Nozzle control governing
3. By-pass governing
4. All of these

Answer 1

Correct Answer - Option 4 : All of these

Explanation:

The objective of governing is to keep the turbine speed fairly constant irrespective of load.

The principal methods of steam turbine governing are as follows 

1. Throttle governing
2. Nozzle governing
3. By-pass governing
4. Combination of 1 and 2 and 1 and 3.

Throttle Governing:

• It is the most widely used particularly on small turbines because its initial cost is less and the mechanism is simple.
• The object of throttle governing is to throttle the steam whenever there is a reduction of load compared to economic or design load for maintaining speed and vice versa.

Nozzle Governing: 

• In this method, the nozzles are grouped together as groups, and the supply of steam to each group is controlled by regulating valves.
• At full load conditions, the valves remain fully open.

By-pass governing: 

• In the case of by-pass governing arrangement is made for a by-passing surplus quantity of steam without allowing total steam quantity to contribute to turbine output when load reduces.