Fluke VIBGUARD compact, Manual, Page: 28 / 50

6.3 RPM sensor
The following section regarding the mounting of an inductive proximity switch is intended for use with GL-
certified VIBGUARD CMS on wind turbines
The machine RPM is a measurement taken with an inductive proximity switch as standard. The proximity switch is
to be mounted as close to the measurement marks on the shaft as possible (e.g. mounted on a separate toothed
washer).
In every revolution the measurement marks generate a pulse with an electrical field change. The RPM is then deri-
ved from the frequency divided by the number of measurement marks on the shaft. The function display (LED) of
the sensor responds during an RPM measurement.
The RPM sensor supplies the raw signal to the VIBGUARD compact directly. It is not averaged. This is specifically
necessary for variable speed units.
A laser optical sensor (e.g. PRUFTECHNIK laser sensor, VIB 6.631) must be used to measure very low
speeds (< 50 RPM). For high-speed applications, the reference mark is to be fastened to the shaft using a
suitable adhesive (e.g. Loctite). The reference mark is to be fastened to a clearly defined position (e.g.
key).
The quicker the shaft rotates and the more switching cams are measured, the more precisely the RPM can
be determined. It is therefore recommended that the RPM sensor is installed on the shaft. The number of
switching cams mustbe noted in the installation log andentered in the measurement configuration in the
OMNITREND Center PC software (context: measuring channel).
CAUTION! When installing the RPM sensor, ensure that the function of the unit's safety equipment is not
impaired.
Mounting the RPM sensor
The RPM sensor of type VIB 5.992-xx is electrically insulated. You can mount it on the machine housing using a sui-
table mounting profile.
RPM sensor mounted, toothed washer as encoder.
28 Edition: 10.2018
Installation and Operation