Which device is responsible for protecting the steam turbine from excessive speed?

The governor assembly plays a crucial role in safeguarding the steam turbine by regulating its speed. It continuously monitors the speed of the turbine and makes real-time adjustments to the input of steam. If the turbine speed begins to exceed safe operational limits, the governor assembly responds by controlling the steam flow, either by reducing the supply or diverting it, ensuring that the turbine does not experience excessive speed. This mechanism is vital for preventing mechanical failure and maintaining the integrity of the turbine system.

In contrast, while pressure relief valves are essential for protecting against overpressure conditions and control valves manage the flow of steam, they do not directly control the turbine's rotational speed. Similarly, flow meters are used to measure the amount of steam passing through a system but do not have a regulatory function to prevent excessive speed in turbines.