Question 630Steam Plants - Assistant Engineer

The correct answer is A) interstage steam leakage along the turbine rotor. Labyrinth packing rings are installed on turbine diaphragms to minimize interstage steam leakage along the turbine rotor. These rings create a tight, labyrinth-like seal that prevents steam from escaping between the stationary diaphragm and the rotating turbine rotor, improving the overall efficiency of the turbine. The other options are incorrect because they do not accurately describe the primary function of labyrinth packing rings. Option B is incorrect as the rings do not directly prevent steam from escaping to the atmosphere. Option C is incorrect as the rings do not minimize pressure buildup on both sides of the diaphragm. Option D is incorrect as the rings do not prevent air leakage from entering the turbine casing.