How to conduct a mechanical overspeed test? What are the qualification criteria?

1. Disconnect the coupling； 2. The supply of water, electricity, and steam for the unit’s auxiliary systems is normal ； 3. The oil circulation of the unit is satisfactory, and the oil pressure is normal ； 4. Over-speed interlock cut-off ； 5. Start the turbine following the normal startup procedure ； 6. After sufficient warm-up, increase the speed in accordance with the speed-up curve, paying attention to changes in bearing temperature and vibration levels ； 7. Check whether the mechanical trip value of the unit meets the requirements; if it exceeds the rated trip value, and there are abnormalities in the unit’s noise level, vibration levels, or bearing temperature, shut down the unit immediately by activating the brake. For the unit to be considered qualified, its speed upon three consecutive mechanical overspeed trips should be within ±1% of the rated trip speed.