MONITORING DEVICE OF TORSIONAL VIBRATION OF SHAFT

PURPOSE:To monitor the status of a motor shaft by finding out the shaft twisting torque of the shaft from electric torque applied to the motor and a attenuation constant calculated on the basis of evaporating status. CONSTITUTION:Main steam discharged from a boiler 1 passes through a main steam valve 5 and the evaporation output is detected by a pressure gauge 6. Steam from a turbine 2 is cooled by a condenser 8 and detected by a flow meter 7. A self-attenuation constant is calculated by an attenuation constant operating device 10 on the basis of the pressure of the steam and the quantity of the steam detected by the pressure gauge 6 and the flow meter 7 respectively and inputted to a shaft twisting vibration torque calculating device 11. Shaft twisting vibration torque in each point is found out on the basis of the self- attenuation constant and the electric torque and an inertia constant and a shaft twisting spring constant which are previously inputted by an arithmetic unit 11 and inputted to a fatigue life operating device 13. The device 13 calculates and displays the life consumption ratio of the shaft room a shaft fatigue curve which is previously inputted, so that the status of the shaft can be monitored.