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C.5 Measuring rate (number of measurement points)
An important criteria for the quality of the results is the number
of measurement values saved. The more measurement values, the
more meaningful the measurement. The decisive factor here is how
quickly the machine reaches the operating RPM or how quickly
it comes to a standstill. The greater the time required for this, the
more measurement values VIBXPERT can record. If the time period
is too short for a sufficient number of measurement values, the
'Overlap' parameter can be increased in the measurement setup in
order to increase the measurement rate (see below and P. 3-21).
In machines the coast up and down very slowly, the number of
saved measurement values can be very high without significantly
improving the quality of the results. In this case, you can reduce the
measuring rate - i.e. the number of saved measurement values per
change in RPM - and save memory space at the same time. In the
measurement setup, set the 'RPM deviation' parameter to a higher
value - either in the measurement setup or immediately before
beginning the measurement (see p. 5-6). In the example below, a
measurement is saved whenever the RPM (rotational frequency*)
changes by 1 Hz.
The 'RPM deviation' parameter in the measurement setups set at the
factory can also be changed.
To display the number of measurement values saved, press the
MENU key in the result screen and click on 'Result Details' (see
below).
Measurement tasks
* 1Hz = 60 rpm.
Note
Left:
Runup / Coastdown - meas. setup
Setup parameters 'overlap', RPM devia-
tion
Right:
Number of saved meas. values
in the 'Result details' screen
5-11
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