During the startup sequence of a steam turbine, which action is performed first?

• A. Open the steam inlet valve slightly to start the turbine rolling.
• B. Close the casing drain valve and ensure the casing drain steam trap remains in service.
• C. Reset the overspeed trip.
• D. Manually test the overspeed trip.

Answer: (C)

Before bringing a steam turbine up to speed, you must ensure the protective devices are in a ready state. The overspeed trip is a crucial safety system that must be reset so it is armed and can respond correctly if speed rising becomes dangerous. If it’s left in a tripped or latched condition from a previous operation, the startup could be blocked or the protection could misbehave, increasing the risk of an uncontrolled overspeed.

Opening the steam inlet valve a little is something you do once the protection is ready, to begin rolling the turbine smoothly. Checking casing drains and traps is important for removing condensate during startup, but these actions don’t enable the turbine to start in the way resetting the protection does. Manually testing the overspeed trip is typically done during commissioning or maintenance, not as the first step in a normal startup sequence.