What device is tripped to safely conduct an offline process for steam turbines?

The overspeed device is critical for the safe operation of steam turbines, particularly when conducting offline processes. This device is designed to monitor the rotational speed of the turbine and is set to trip or shut down the turbine if it exceeds a predetermined safe speed. This is essential for preventing catastrophic failures, such as mechanical damage or even explosions that can occur if the turbine operates beyond its design limitations.

When a turbine is taken offline, there are various operational changes, and ensuring it does not reach overspeed conditions is paramount for safety. Thus, the overspeed device serves as a safeguard, helping to maintain control over the turbine during these processes, ensuring that the system operates within safe parameters.

Other options, while they play roles in system safety as well, serve different purposes. An emergency brake is generally used in other types of machinery or systems to stop movement quickly in urgent situations but is not specifically linked to safely managing steam turbine operations. A safety lock relates more to the locking out of equipment for maintenance and is aimed at preventing unauthorized access rather than directly managing operational speeds. A pressure relief valve is crucial for managing pressure within the system, safeguarding against overpressure conditions but does not directly control the speed of the turbine.