National Instruments Order Analysis Toolset - Manual (Page 46)

Chapter 4 Resampling-Based Order Analysis
LabVIEW Order Analysis Toolset User Manual 4-6 ni.com
When monitoring shaft vibration with a proximity probe, the acquired
signal contains not only the vibration of the shaft but also the shaft runout,
such as a nonconcentric shaft condition at the probe measurement plane.
You can measure the shaft runout at a slow roll speed and can compensate
for it in the raw proximity probe signal. Figure 4-4 shows the raw signal
acquired from a nonconcentric shaft and the compensated signal.
Figure 4-4. Slow Roll Compensation
The LabVIEW Order Analysis Toolset can perform the vector-based slow
roll compensation on order magnitudes and phases. The toolset performs
slow roll compensation subtracting a slow roll vector from the measured
magnitude and phase. Use the OAT Extract Slow Roll Vector VI to compute
the slow roll vector from a slow roll signal. Use the OAT Slow Roll
Compensation VI to remove the runout components from the measured
magnitude and phase. If no slow roll vector is provided, the OAT Slow Roll
Compensation VI automatically uses the first magnitude and phase pair as
the slow roll vector.
Shaft Center
Rolling Center
Amplitude
Amplitude
Raw Signal
Compensated Signal