5-14
VIBXPERT 11.2010
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
unbalance). The
synchronous phase measurement
determines the
amplitude and the phase angle of the vibration pointer from the
RPM-synchronous 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 unbalance 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,
dynamic 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
difference is an indicator of the presence of a machine fault.
Enter the RPM of the machine before the measurement as a
measurement 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
respective values for amplitude and phase angle are displayed in the
result field below the diagram (see below).
A: Result for channel A
B: Result for channel B
Max. display range
2 channels
'Advanced' tab
1 channel
'Overall values' tab
Synchronous Phase
Cross Channel Phase
2 channels
'Advanced' tab
Left:
Synchronous phase measurement
Right:
Cross Channel phase measurement
Summary of Contents for VIB 5.300 EX Series
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