On the principle of the key phase of the unit shafting.

Condition monitoring of machinery and equipment is a course; I haven’t studied it either, but I can read books on the topic, such as Condition Monitoring and Fault Diagnosis of Mechanical Equipment

With an axis diameter of 360 degrees, the keyway serves as the reference point at 0 degrees. By determining the time when the vibration peak occurs in relation to the key pulses, it is possible to calculate at which position on the axis the vibration peak takes place, as well as the degree distance from the keyway

It’s better to just look at displacement and vibration; use this for measuring speed, though it’s usually the 45 or 30 key.

I don’t really understand it either; I only know that the rotation speed can be used as a reference. This information was taken from the internet, and I hope it will be helpful. 1. Key phase is also known as phase reference. 2. Phase measurement is achieved by placing a groove on the shaft under test, known as a phase mark. When this groove moves to the probe position, it results in a sudden change in the distance between the probe and the surface being measured; the sensor then generates a pulse. One pulse is produced for each full rotation of the shaft, and the timing of these pulses indicates the position of the shaft during each rotation cycle. Therefore, by counting the pulses, the rotational speed of the shaft can be measured, and by comparing the pulses with the vibration signals of the shaft, the phase angle of the vibration can be determined, which is useful for dynamic balance analysis of the shaft as well as for fault analysis and diagnosis of equipment. 3. The key functions of phase are four: The first function is to measure the rotational speed, and it is mainly used in devices with variable frequency drives ； The second function is that, whether the equipment is starting up or shutting down, it must pass through the critical speed (except for rigid shafts); by using key phase in combination with a shaft vibration probe, it is possible to capture the vibration trends during startup and shutdown ； The third is to detect axial distortion of the rotating shaft during normal use, as such an abnormality can lead to the destruction of the rotating shaft*, although it occurs very rarely! However, since this kind of deformation cannot be detected by a regular shaft vibration probe on its own, this is called phase angle measurement ； The fourth function is to, in conjunction with the shaft vibration probe, obtain the real-time axis position of the rotating shaft in order to analyze bearing disturbances or eddy currents. Phasor analysis is primarily used for vibration analysis of rotating equipment. It is said that when the rotor vibrates excessively, counterweights need to be added; however, to determine where the vibration is most severe and where to place the counterweights, phasor analysis is necessary. The phasor represents the starting point and ending point on the rotor’s circumference, and it helps identify at which angle on the phasor the exact point of vibration lies when the rotor vibrates heavily. It is mainly used in conjunction with eccentricity to assess the vibration condition of the main shaft