Power Engineering - 2B1 exam 2023 with 100% correct answers

What is bowing and what causes it? - correct answer When the turbine is still and left cold the mass of the rotor can cause it to sag What is hogging and what causes it? - correct answer When the turbine is still and left hot. The bottom half will cool quicker than the upper half causing the rotor to bend upwards What are turning gears? What are they also called? - correct answer Barring gears. Turn the turbine at slow speed to reduce hogging and bowing What speed do turning gears typically turn a turbine? - correct answer Between 20 and 40 RPM but some as low as 3 RPM How does running turning gears cool? What does it cool? - correct answer The fan action of the turbine cools the turbine and bearings How long do turning gears operate before starting up a steam turbine? - correct answer 3 hours How long do turning gears operate after shutting down a steam turbine? - correct answer 24 hours What can be said about hydrogen cooled generators and turning gears? - correct answer When shutdown the turning gears keep the turbine turning all the time. This is so as to prevent hydrogen from escaping through the shaft seals What type of lubrication is needed when turning gears are operating? - correct answer When turning gears are operating the mechanical oil pump will NOT provide enough lubrication. Therefor the auxiliary pump is use