Vibration diagnosis method and apparatus for rotary machines

A vibration diagnosis method for rotary machines comprising the steps of measuring vibration of the rotor shaft of a rotary machine;

• extracting from the measured overall vibration the vibration component synchronous with the revolution of said rotor shaft;
• comparing the amplitude of the synchronous vibration with the amplitude of the overall vibration;
• analyzing said synchronous vibration;
• judging the result of the analysis of the synchronous vibration component;
• and displaying the result of the judgement in a diagrammatical manner;
• the step of analyzing the synchronous vibration component further including the step of comparing a difference between the rates of change of the amplitude of vibration components at two adjacent points of time with a second predetermined value.

A vibration diagnosis method for rotary machines comprising the steps of measuring vibration of the rotor shaft of a rotary machine;

• extracting from the measured overall vibration the vibration component synchronous with the revolution of said rotor shaft;
• comparing the amplitude of the synchronous vibration with the amplitude of the overall vibration;
• analyzing said synchronous vibration;
• judging the result of the analysis of the synchronous vibration component;
• and displaying the result of the judgement in a diagrammatical manner;
• and further comprising the step of memorizing a plurality of vibration data synchronous with the revolution of rotor shaft and obtained in a predetermined period of time;
• and wherein the step of analyzing the synchronous vibration component includes the steps of successively calculating, when the vibration of said rotor shaft is not attributable to an abrupt generation of mass unbalance, change of vibration vectors of the memorized vibration data with the passage of time, and judging whether there exists an unbalanced vibration due to thermal bow of said rotor, through analyzing change of vibration vector with the passage of time, in respect to phase and amplitude.

A vibration diagnosis apparatus for rotary machines, comprising:

• a vibration detector for detecting vibration of a rotor shaft of a rotary machine;
• an A/D converter for analog-to-digital conversion of said vibration signal;
• a data processing unit for extracting from the converted vibration signal the vibration component synchronous with the revolution of said rotor shaft;
• a waveform converter for imparting a phase reference signal to said data processing unit;
• a timer clock adapted to impart a timing signal to said data processing unit;
• a first judging device adapted to make a judgement as to whether the synchronous vibration component delivered by said data processing unit is an unbalanced vibration or not;
• means for analyzing the cause of said synchronous vibration component;
• and a display unit for displaying the result of the analysis made by the analyzing means.