What is the proper way to stop a steam turbine when taking it offline?

To properly stop a steam turbine when taking it offline, tripping the overspeed device by hand is an important safety measure and is generally the most effective action to take. The overspeed device is designed to automatically shut down the turbine if it exceeds safe operational speeds, which can occur during an emergency or fault condition.

Manually tripping the overspeed device ensures that the turbine stops quickly and safely, preventing potential damage from high-speed operation and ensuring that it comes to a stable stop. This action also allows the operator to take control of the shutdown process, ensuring it is done in line with the operational protocols and safety standards.

In contrast, shutting down the power supply does not directly address the immediate need to control the turbine's operational speed and can lead to unsafe conditions if the turbine continues to run for a moment. Draining the turbine’s steam might be part of a complete shutdown procedure, but it should occur only after ensuring the turbine has safely come to a stop. Reducing the fuel supply is typically a method used for managing the turbine’s output but is not an immediate or effective means of shutting it down rapidly and safely.