What Do These Phase Angles Mean ?

We have checked the radial vibration at 2 angular locations around a single bearing. This has provided us with two valuable pieces of information. The first is: When triggering the strobe light from the vibration signal, the shaft appeared frozen. In other words, the mark was not rotating - it remained stationary (even if it wobbled back and forth a bit). What does this mean ? It means the vibration IS coming from this shaft. This is now established as FACT - something only a phase reading can do (as we will see later in the 'Plots' section). What is the second piece of information ? When moving the transducer to a new angular location (moving from horizontal to vertical is 90°), the location of the mark (the phase angle) shifted the same amount (90°). What does this mean ? The shaft is vibrating in a more circular orbit that typically indicates unbalance. Let's examine each of these facts more closely and see how they were arrived at from the phase measurements we recorded.