When is the barring gear engaged on a hot turbine?

The barring gear is engaged on a hot turbine primarily to ensure that the rotor is rotated slowly and uniformly to distribute thermal stresses evenly. This action is crucial after the turbine has been operating at high temperatures. Engaging the barring gear helps prevent distortion, warping, or any structural stress that can occur due to temperature differences across the turbine's components.

It is common practice to engage the barring gear for an extended period after shutting down a turbine. Typically, allowing at least one hour or more is essential as it provides sufficient time for the components to cool down gradually and evenly. This method reduces the potential for damage caused by thermal shock and helps in maintaining the integrity of the turbine system during the cooling phase after operation.

Understanding the proper timing for engaging the barring gear is vital for the longevity and reliability of turbine systems, which is why the one hour plus option is the most appropriate choice in ensuring optimal condition for turbine components.