5-16
VIBXPER
T II 05.2012
Orbit
The movement of the shaft axis* at constant speed is measured with
two non-contact sensors that are installed in an angular distance of
90 °.
This enables identification of machine faults and damage to the shaft
that become apparent in the vibration behavior of the shaft and di-
rectly affect the path of the shaft (e.g. unbalance, misalignment, shaft
crack, rotation fault - for more details, see VDI 3839 Sheets 1 and 2).
When using 'filtered orbit', the signal is processed in an order filter
and therefore requires a keyphaser to provide a reference.
A typical measurement installation is shown in the following figure:
- The two displacement sensors are mounted in a single measure-
ment plane at an angular displacement of 90° on the machine.
If this angular displacement is not possible, you can mount the
sensors at any angular displacement between 5° and 175°. Then
enter the angular displacement in the measurement setup ('Sen-
sor angle' parameter). However, measurement accuracy is limited
when the sensor angle
≠
90°.
- The sensor on channel A defines the X direction and the 0° posi-
tion.
- The keyphaser is mounted in the 0° position.
- Note the setting of the active edge for the trigger signal (see: Key-
phaser Menu/Device Setup, p. 2-23).
The procedure for an orbit measurement is described in the follow-
ing standards: ISO 7919, ISO 10817-1, VDI 3839 Sheet1.
A description of the measurement procedure with VIBXPERT can
be found in the Technical Information CM # 18 'Analysis of radial
shaft movement in journal bearings’ - available free on our website.
Typical installation
with inductive displacement sensors
Measurement tasks
Note
filtered
unfiltered
* The movement of the shaft axis while
the machine is running up / coasting
down is recorded with a shaft centerline
plot (see p. 5-12).
Channel A
(VIB 6.640)
Channel B
(VIB 6.640)
Keyphaser
(VIB 6.631)
Summary of Contents for VIBXPERT II
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