VMI VIBER X4, Manual, Page: 36 / 58

Vibration Measurement Instruments
Measure Envelope
There are three windows at the top of the screen. The left win-
dow shows the amplitude of the cursor, the middle window
shows the frequency of the cursor and the right window shows
the total value.
The scale for the value is displayed above the spectrum chart and
the range below the spectrum chart.
During measurements, the following actions can be performed:
•
Default zoom Ctrl + F1
Set the zoom back to default mode.
• Cursor type Ctrl + F2 Change cursor type between LINE,
PEAK and FREE.
• Settings F3
Enter the settings menu.
• Aux cursors Ctrl + F3 Add different types of cursors such as
Harmonic or Sideband.
• Move the cursor using the Left and Right arrow keys. When
pressing the key once the cursor will move one line at a time,
when keeping the key pressed the cursor will move fast 10 lines
at a time.
• Zoom in or out of the X Scale using the Ctrl + Right arrow
or Ctrl + Left arrow keys. During zooming, the cursor remains
visible on the spectra.
• Zoom in or out of the Y Scale using the Up or Down arrow
keys. Notice that once the zoom occurs on the X or Y Axis, the
plot will not be auto scaled. Instead, the manual settings are used.
Press Ctrl + F1 (Default Zoom) to re-enable the auto-scaling
mode.
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Envelope
Envelope is a spectrum measurement that enhances the energy in the high frequency signals and is used to
find early signs of bearing faults. Envelope can also be used to detect cavitation in pumps. When you want to
see the fluctuations of high frequencies it is better to use the unit “g” (acceleration) because the acceleration
signal increases in signal level when the frequency increases.
Envelope signals have their own unit “gE” (Envelope acceler- ation). The level of an envelope signal de -
pends more on how much fluctuation a certain fault can create in the original signal, and not on the serious -
ness of the fault itself. It is therefore difficult to compare two different measuring points, but it is possible to
compare two Envelope spectra at the same measuring point.