5-14
VIBXPER
T II 05.2012
Measurement tasks
Phase measurement
The phase measurement is used to identify machine faults that cause
lines at the same position in the spectrum (e.g. static/ dynamic unbal-
ance). The
synchronous phase measurement
determines the amplitude
and the phase angle of the vibration pointer from the RPM-synchro-
nous components of the vibration signal. The reference transducer in
this case is a trigger sensor (see p. 5-5). To simplify the diagnosis, the
measured signal is processed in an order filter. For example, an un-
balance causes severe vibrations in the first order whereas alignment
faults dominate in the second order.
Synchronous phase measurement can be performed in one or in two
planes. With two channel measurements the phase difference in both
planes can be determined. This indicates whether, e. g. static, dynam-
ic or coupled unbalance is present.
In contrast to synchronous phase measurement, the
Cross Channel
Phase Measurement
is determined without a reference transducer.
The measurement is carried out as a 2-channel measurement where,
in addition to the signal amplitudes, the phase difference of the two
channels is determined. Depending on where and in which direction
measurements have been carried out on the machine, the phase dif-
ference is an indicator of the presence of a machine fault.
Enter the RPM of the machine before the measurement as a measure-
ment parameter. The size of the RPM range to be evaluated is set in
the measurement setup ('RPM range' parameter, see P. 3-23). Note the
setting of the active edge for the trigger signal (see: Keyphaser Menu/
Device Setup, p. 2-23).
The measurement result is displayed in a polar diagram. The respec-
tive values for amplitude and phase angle are displayed in the result
field below the diagram (see below).
2 channels
'Advanced' tab
1 channel
'Overall values' tab
Synchronous Phase
Cross Channel Phase
A: Result for channel A
B: Result for channel B
Max. display range
Left:
Synchronous phase measurement
Right:
Cross Channel phase measurement
2 channels
'Advanced' tab
Содержание VIBXPERT II
Страница 175: ......