Predictive Maintenance depends on the very important principle, what is this principle? And what are the techniques of this principle?

The basics of predective maintenance are given by the four steps :

1- Event : reference to a timeline  in relation to an event type (auto diagnostic information from a sensor, measurement of wear, etc.)

2-Maintenance methods :systematic preventive maintenance / conditional preventive maintenance

/ corrective maintenance

3- maintenance inspection, monitoring, troubleshooting, repair, etc.

4- Related activities: Maintenance Improvement, renovation, reconstruction, modernization, new construction, security, etc.

predictive maintenance is done after condition monitoring which includes vibration analysis and keen observation of local  parameters such as amps. noise, any abnormalities etc. one could do predictive maintenance only after collecting  these valuable data.