Superior Signal Company LLC
AccuTrak
®
VPX-WR
User’s Manual
© 2015
16
DATA COLLECTION AND TRENDING
The VPX-WR provides the user with a narrow band signal that is used to detect and record
ultrasonic sounds in the range of 34 to 42 kHz. Use the special cable option that converts
the Multi-pin plug to a BNC. Plug the BNC to a spectrum or a vibration analyzer to record
the waveform.
Set the VPX-WR control to maximum. Set the analyzer attenuation at midrange. Take a
reading. If the waveform fills the screen completely, increase the attenuation of the
analyzer (Less sensitive). If the waveform is barely visible decrease the attenuation, and
repeat this process until you learn the settings for the analyzer. In certain situations you
may need to decrease the sensitivity of the VPX-WR if there is strong background noise.
Start testing new machines or new bearings first. This will help you establish a base line
in the amplitude and the nature of the harmonics present at the test point. Periodic tests
at the same location will show the difference between the normal condition and a
developing fault. New frequencies that were not present in previous tests will appear, the
amplitude of existing ones will change. Early frictional faults will appear as high
frequencies.
The amplitude of the output signal is 0 to 750 mV, and the frequency range is 0 to 4 kHz.
The actual ultrasonic frequency is 38 kHz plus (or minus) the observed translated
frequency. This means that if you observe a peak in your analyzer at 1600 Hz it comes
from a 38+1.6=39.6 kHz source. (or 38-1.6=36.4 kHz).
TIPS ON USE:
Use Excel or a similar spreadsheet software tool to graph your results. Excel has an
extensive graphing capability. If you need more graphing power including curve fitting
use Axum.
