How to find trend change in a time series?

Question

Analytics

Hello. I'm interested in a tool that can be used to evaluate the change in time series. Suppose there is a time series representing the dependence of vibration acceleration on time. A sensor that converts vibration accelerations into a signal is located on a certain machine. It is necessary, using sensor data, to understand when the machine was working and when it was at rest. How can this be done with math?