PRÜFTECHNIK VIBXPERT II - RPM Measurements; Installation and Adjustment

5-4
VIBXPERT II 05.2012
Measurement tasks
RPM measurements
The Laser-TriggerSensor(VIB6.631)isusedforRPMmeasurement
and as a trigger encoder. The sensor detects the signals optically, i.e.
without contacting rotating machine parts during the measurement.
Red laser light is emitted from the sensor head and strikes a measure-
ment mark on the rotating shaft. The measurement mark can be light
amplifying(e.g.reectivelmVIB3.306)orlightattenuating(ablack,
high contrast line on a light-colored surface). Each time the sensor de-
tects a difference in brightness, it sends an electric impulse. VIBXPERT
calculates the shaft RPM* based on the repeat rate of the pulses.
Installation and adjustment
• Mount the laser trigger sensor on the machine with the trigger
stand(VIB6.632).Themaximumdistancetotheshaftis2meters.
• Applyasuitablemeasurementmarkertothestationaryshaft(e.g.
areectivetape-VIB3.306).
• Connectthelasertriggersensortothemeasurementdeviceusing
thetriggercable(VIB5.432-2.9).
• To adjust the system, point the laser beam at the measurement
marker while the machine is at a standstill.
 Switchonlaserforadjustment:Inthecaseofcoast-downmeasure-
mentsthelaserautomaticallyswitchesonpriortothemeasurement;
duringbalancingthelasercanbeswitchedonmanually;inallother
cases, you must start an RPM measurement for adjustment.
The laser beam should be slightly inclined to the shaft surface and
shaft axis. The maximum permissible angle deviation depends on
the type of measurement marker.
Do not look into the laser beam! Risk of eye damage!
Do not open the housing!
Laser trigger sensor (VIB 6.631)
(technical data: see the sensor catalog)
Laser / sensor
* If shaft speed < 0,1 Hz (= 6 rpm), then
change the 'Keyphaser - Timeout' set-
ting in the Device setup (p. 2-23).
WARNING!
Signal response
Light reinforcing mark (VIB 3.306):
signal rises from 0 V to 5 V.
Light damping mark (black line):
signal drops from 5 V to 0 V.
Acceptable angular deviation:
± 45° (Reflective mark)
± 15° (Contrast mark)
Sensor
Shaft
Adjusting
0 V
5 V
0 V
5 V