Over speed test will be executed to ensure that the pump will tripped due to over speed.
There is an electronic tripped set point by governor valve closing when the actual speed reach to maximum governor speed as well as Mechanical trip which will occur when the speed reach to electronic tripped and the valve not close due to malfunction of governor valve. Mechanical latch lever will slid to cut the HP steam.
Electronic maximum governor speed will be less than mechanical speed set point.
It could overspeed and wreck itself-but there are emergency stop valves as well as the governor, so it is unlikely.
Overspeed trip.
Steam is redirected back into the boiler from the high-pressure turbine for reheating, but the steam from the low-pressure turbine enters into a condenser to become water again.
manish
axial shift of a steam turbine is the shifting of turbine rotor in the forward and backward direction due to steam thrust on blades of rotor.
Run the turbine up to about 75% speed and trip it manually. Reset the trip linkage. Restart the turbine. Adjust the governor up until the overspeed trip mechanism trips the stop valve. Watch the tachometer, the overspeed trip should activate within 10% over the maximum allowable speed of the turbine, if it doesn't trip it manually and repair the trip.
by means of mechanical or electrical overspeed protection mechanism
Overspeed is usually the result of too small of a turbine housing/wheel used.
It could overspeed and wreck itself-but there are emergency stop valves as well as the governor, so it is unlikely.
in a steam turbine, it is the speed at which the turbine should not go above. some time they call it overspeed trip. because the turbine rotor and berings are not design for such high speed and is not capable to handle this huge cenerfugal forces. usually there is two type of trip system: Electronic and Mechanical. some Steam Turbins have both protaction system.
Typically two balls with springs holding them down, When the turbine spins too fast, the centrifugal force pushes the balls past the resistance of the springs at which point they hit a lever that stops steam/compressed gas flow to the turbine and the turbine shuts down. They are designed to keep the turbine from going so fast that it damages itself or the piece of equipment it is driving.
The TSI system is Turbine Supervisory Instrumentation system, consists of multiple instruments, including speed sensors, speed monitors and so on. The system continuously monitors the steam turbines of all important parameters, such as: rotational speed, overspeed protection, eccentricity, shaft vibration, cover vibration, axial displacement, differential expansion, and thermal expansion. The system helps to improve the availability of steam turbine unit.
Overspeed trip.
Why extractions are taken out from steam turbine.
Steam is redirected back into the boiler from the high-pressure turbine for reheating, but the steam from the low-pressure turbine enters into a condenser to become water again.
The preventive maintenance of steam turbine mainly entails frequent servicing of the parts. This will ensure a smooth performance of the steam turbine.
manish