eZ-Analyst
889691
Edit Menu 4-13
Time Sync
:
Time synchronous averaging uses a keyway, or a similar point of reference, as a trigger.
The blocksize is set to allow enough time for at least one full revolution. This must be performed in
Scope Mode. Channel trigger mode should be used in conjunction with this selection.
Number of Averages
: This number specifies the condition for terminating a data acquisition sample.
After the number of averages (blocks/frames of data) have been captured and averaged, the
eZ-
Analyst
will automatically stop taking new data. This sample can then be saved. If the number of
averages is set to zero, acquisition is continuous and must be halted by the user.
Continuous Measurement
: Checking this option restarts the
averaging process
without user
intervention. Note that the data itself is not continuous between measurements. This option is not
meaningful for
non-averaging
operations.
Save after Averaging:
When this option and continuous measurement are enabled, data will be
exported to function data sets when the desired number of averages has been completed. If this option
is not enabled, user has the option of manually saving an MDS file or exporting data.
How to Perform Negative Averaging
1. Perform an impact measurement, with Averaging set to “
” and “
Triggered
Acquisition
.” Take 5 to 10 impacts on a running machine.
2. Select “
Spectrum Display
.” View Results.
3. Then change to “
Free Run Acquisition
” with Averaging set to “
Linear –
.”
Take 10 to 20 averages.
4. Start
Scope Measurement
. Select “
Use Current Spectrum as Reference
.”
Note that the Displayed Spectrum is a
Negative Averaged Spectrum
. The running
Spectra is subtracted from the Running, and you are left with the Impact
vibration.
In regard to the following three screen shots, the first shows the impact spectra on the
non-
running motor
; the second shows the impact spectra on a
running motor
; and the third shows
the
Negative Average
spectra. If you compare the Negative Average spectra to the non-
running impact you will notice that the Running Speed vibration has been subtracted out,
leaving Resonances.
Reference Notes
:
The following sections of this document contain information that closely relates to the
subject of Averaging. Reading over the following material should improve your
understanding of the important concepts involved.
Function Data Sets,
page 3-12
Capturing Transient Data
, page 4-10.
How to Perform Negative Averaging
, 4-13.
Recording Setup,
page 4-33.
Block Rejection Tab
, page 4-36.
Considerations Regarding Double Hammer Rejection,
page 4-37.
