PRÜFTECHNIK VIBXPERT - DC measurements; Application examples; Setting up a measurement task for measuring the DC components

5-30
VIBXPERT 11.2010
Measurement tasks
DC measurements
For the following measurement tasks, the DC component in the signal
can be recorded in addition:
- Time waveform with the measuring quantity set to vibration
displacement or user-defined*.
- Spectrum with the measuring quantity set to vibration displace-
ment or user-defined*.
- Phase with the vibration displacement measuring quantity .
- Coastdown, amplitude/phase with the measuring quantity set to
vibration displacement or user-defined*.
- Orbit (unfiltered), with the measuring quantity set to vibration
displacement or user-defined*.
- Time waveform recorder, with vibration displacement measuring
quantity.
Application examples
The DC component in the time waveform can be evaluated when
process parameters or distances are measured.
When a 2-channel coastdown curve is measured with the vibration
displacement measuring quantity, the shaft centerline plot during
runup or coastdown in a machine with journal bearings can be
calculated from the DC component of the signal (see p. 5-12).
Setting up a measurement task for measuring the DC components
You can activate a DC measurement in the measurement setup using
the 'Lower frequency = DC' parameter (see p. 3-21 / 3-23). You must
also set up the 'Vibration displacement' or 'User-defined' measuring
quantity and assign a suitable sensor.
Setting up a DC measurement
Measuring quantity = 'Displacement'
or 'User'
Lower frequency = 'DC'
* see page 5-19