PRÜFTECHNIK VIB 5.300 EX Series, Руководство по эксплуатации

Страница: 127 / 172

5-11
VIBXPERT 11.2010
Measurement tasks
C.5 Measurement 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 measure-
ment 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 mea-
surement (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).

Note
* 1Hz = 60 rpm.
Left:
Runup / Coastdown - meas. setup
Setup parameters 'overlap', RPM
deviation
Right:
Number of saved meas. values
in the 'Result details' screen