Introduction
All SKF Eddy Current Probes are sealed units and contain
no user-serviceable parts. The only maintenance
performed by the user consists of making sure all
connections are tight and clean. This section explains
how to calibrate the probe drivers and troubleshooting
techniques associated with suspected probe failures.
Periodic/preventative
maintenance
SKF Eddy Probes will give many years of maintenance-
free service if used within the parameters listed in the
eddy probe specification data sheets. See SKF Condition
Monitoring publication “Eddy Probe Systems Catalog”
(CM2004).
Calibration
Calibrating probes just prior to extensive equipment testing
ensures the accuracy of test information and optimizes
very costly test time.
Section 6
Maintenance
CMSS 601 Series Field
Calibrators
Description
The Model CMSS 601 Series Field Calibrators are basically
a micrometer with a magnetic base and adapters to accept
either the CMSS 60, CMSS 61, CMSS 65, or CMSS 68
Series Eddy Probes. The CMSS 601-1 measures the gap
in milli-inches (mil) and the CMSS 601-2 and
CMSS 601-8 measures in micrometers. The CMSS 601-1
and CMSS 601-2 can be used with the more common
short eddy probe case lengths however the Model CMSS
601-8 MUST BE used with eddy probe case lengths
GREATER than 2.5 inches (65 mm).
The field calibrator provides an adjustable static gap across
which the probe observes a target of precisely the same
material that the probe will observe when installed as part
of the machine monitoring system. Due to differences
in conductivity and permeability, different materials
(metals) have different gap-to-voltage sensitivity. The
length of the gap and the output of the eddy probe can
be both accurately measured, and a calibration curve
can be generated from the readings. The calibration
potentiometer on the various models of the eddy probe
drivers is then adjusted for a 200 mV/mil scope of the
calibration curve.
Note: Wherever possible, mount the field calibrator on the
actual shaft to be observed by the eddy probe being
calibrated. Calibrators for long probes use an integral
calibrator target only … will not observe actual shaft.
Section 6 – Maintenance
6-1
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