Next Meas Functions - Adash VA4 Pro II User Manual

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Samples
time length is displayed under this item.
Lines
under this item.
Orders
Avg
How the averaging is used depends of type of trigger:
freerun
continuously
external
without waiting for next trigger
tacho
amplitude
manual
Averaging
Time synchro averaging works in this way: the time signals are averaged (must be controlled by tacho in most
cases) and from averaged time waveform is calculated the final spectrum. It can be set for non-enveloped and
non-zoomed spectra.
Overlap
Resolution
measurement, the choice of resolution is available. The number of FFT lines must be chosen in the
computational procedure. The FFT with fewer lines is faster and displays results more often. When you select
higher resolution (e.g.speed / 64 or even speed / 1024), then more lines must be used and you will wait for
results longer time. If you have some considerable spectrum amplitude near the speed frequency, then you
need to select the higher resolution. It eliminates the disturbing influence of the non speed frequency near the
speed.
Example: the speed is 25Hz. The resolution is speed/4, i.e. 6.25Hz. The speed line bandwidth in FFT will be
6.25Hz. It means, that speed line contains all frequencies in the interval (21.875 , 28.125). If any disturbing
frequency is in that interval, then higher resolution must be used.
Frequency speed, value
manually (value) or can be used the speed frequency from tacho sensor.
Full spectrum

Next Meas functions

Copy copy of selected measurement to the new one
Info displays measurement properties
Edit enables changes in measurement properties
Delete deletes selected measurement
Export to uff exports data of selected measurement to the uff file format (not for all measurement types), the
file is saved to uff folder on VA4_DISC.
If the Actual measurement is displayed then only this data will be exported.
If the saved data are displayed (View Trend) then you can export just one displayed data or all data saved in
memory. The unit asks you Export (All/One)? and then you select the button.
For further technical and contact information visit
value Number of samples ( Speed control = off). The correspondent signal
value Number of lines. The correspondent signal time length is displayed
(1/2,1-5), (1-5), (1/2,1-10), (1-10)
value averaging number
when the measurement is started, all signals needed for averaging is taken
when the external trigger comes, all signals needed for averaging is taken continuously
every signal for averaging is triggered (constant phase)
every signal for averaging is triggered (constant phase)
first signal for averaging is triggered manually, next signals are taken freerun
linear, peak hold, time synchro (for spectrum)
linear, maximum, minimum, median (for static values)
% value Overlapping of signals in averaging.
speed / 4 – speed / 1024
the frequency value for phase shift measurement can be entered
yes, no the spectrum will have two sides, positive and negative (see literature
about turbine analysis for more details).
It is important to define correct sequence of channels. It must match
the rotation direction. It means, the tacho mark must come to
A channelCH1 first and then to B channel. Otherwise the
positive/negative parts would be transposed.
When you use the tacho for 1x amp+phase
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Adash 4400 – VA4Pro