Fundamentals of Rotating Machinery Diagnostics
5 The Orbit
In the chapter on timebase plots, we saw how rotor dynamic motion along the measurement axis of a single transducer can be displayed as a time varying waveform. While the timebase plot can provide important and useful information, it is inherently limited to one dimension of rotor motion. Since, in any lateral plane along the rotor, the rotor moves in a two-dimensional path, or orbit, this one-dimensional picture provided by a single transducer is not adequate.