Steam turbine shaft vibration and vibration of relations

Shaft vibration of rotating shaft radial vibration and axial vibration of steam turbine unit now prevailing eddy current probe is used to measure. Its probe with high frequency current in coil, produces the high frequency electromagnetic field and the induced current measured rotor shaft neck appearance, translate into voltage. And the voltage between the shaft appearance and sensor interval changes and changes, so the measurement of shaft vibration is completed. Axis normal use of vibration displacement value, the unit is microns. If the spread of vortex sensor fixed on the bearing shell, acquisition is the relative vibration between the shaft and bearing; If the sensor is fixed on the bedrock, the acquisition of approximate thought it was the absolute vibration of rotor vibration. The bearing vibration of vibration, also calls the bearing vibration. Ordinary by the contact of the speed or acceleration sensor, ordinary fixed on the bearing cover directly or through magnetic adsorption on it, is sometimes called a shell vibration, vibration. Vibration measurement is given priority to with vertical direction and degree of findings and the direction of axial vibration as a reference. Turbine and generator rotor is supported by bearings, the vibration of the rotor is bound to be transmitted to the bearing, so there are both some contact, including amplitude, phase, frequency, etc. 1, and the size of the amplitude of the two relations. Axial vibration and tile vibration amplitude ratio relation with the stiffness of the bearing has a lot to do, usually, if the bearing seat rigid support ( Such as ordinary floor bearing) That the shaft vibration amplitude value is about 3 ~ 6 times of the vibration. If support such as weak stiffness, the ratio will be reduced accordingly, so that can present the conditions (tile vibration is greater than the shaft vibration Such as the east steam 60 tile sets of low-pressure rotor bearing cylinder type) ； 2, phase relationship. Tile common for speed value of vibration and its phase front axle vibration displacement value of 90 °, line speed values to transform for the displacement demand 90 ° phase Angle. If the vibration is provoked by the disequilibrium, uneven quality of phase and has a fixed shaft vibration phase, at the same time it relation with tile boost phase is similar, it is because of such a relationship, make it possible to site after tile stop vibration dynamic equilibrium. 3, the relationship between the frequency. Can divide frequency components, both difference will speed value integral red shift value, local high-frequency lose weight, so in the rolling bearing, fan wheel, pump body, impeller structure complicated mechanical vibration measurement, habits with vibration velocity values to stop problem, because it can provide more abundant spectral information. The vibration of turbo-generator set is used more domestic relative axial vibration, it reflects the rotor related to support or vibration of the cylinder block, the axial vibration of the rotor, said when the rotor rotation in a week, separate equilibrium interval of large displacement. Vibration is an absolute vibration, and reflect the bearing seat and other related to the vibration of the foundation. In the modern steam turbine vibration testing, axial vibration and vibration are necessary. If a relative rotor shaft vibration is very small and vibration is very big, means standing in a solid in the movement of the cylinder body coordinates, the rotation associated with changes in displacement of the support system is small, the relative contact can prevent; But the rotor dynamic stress and the dynamic stress of bearing branch received still depends on the cylinder body own vibration value; Large cylinder body and bearing vibration, accept the dynamic stress of rotor and components must be high, so any excessive axial vibration and tile vibration is unsustainable.