Question 588Steam Plants - Assistant Engineer

The correct answer is D) prevent uneven cooling of the turbine rotors. When securing the main turbines, the jacking gear must be engaged as quickly as possible to prevent uneven cooling of the turbine rotors. This is because rapid cooling can cause thermal distortion and stresses in the rotor, which can lead to damage. Engaging the jacking gear helps maintain an even, controlled cooling process to avoid these issues. The other options are incorrect because they do not directly address the need to prevent uneven cooling of the turbine rotors, which is the primary reason for engaging the jacking gear quickly when securing the main turbines.