Under what condition does the MFP turning gear operate?

The MFP (Main Feedwater Pump) turning gear operates specifically when the turbine speed drops below 2 rpm. This condition is crucial because the turning gear's primary function is to maintain the mechanical integrity of the turbine. When the turbine is at low speeds, particularly below this threshold, the turning gear helps to prevent damage to turbine bearings and other components by rotating the turbine slowly. This continuous slow rotation ensures proper lubrication, distributes heat, and avoids areas of stagnation or localized wear.

In scenarios where the turbine speed is higher or during normal operational conditions, the turning gear is not typically required, as the turbine system is capable of maintaining its own mechanical stability. The turning gear is specifically engaged when the turbine is in a vulnerable state, such as during a shutdown process or when the turbine is not rotating sufficiently, underscoring the importance of its operation in preserving the life and efficiency of the turbine system.