Kaman KDM-8200 - Manual (Page 26)

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Kaman Precision Products
Calibration
Factory
All systems are factory calibrated; even so, we recommend that upon receipt you check the
Calibration calibration and recalibrate the system using one of the procedures outlined on pages of this
section. At the factory, systems are calibrated with a typical output sensitivity as shown in Part 3:
THE EQUIPMENT, sensor specification table on page 23. We use flat aluminum to optimize for
nonmagnetic targets and 4130 cold rolled steel to optimize for magnetic targets.
Calibration
The importance of proper calibration cannot be overemphasized because it is calibration which
Interval firmly establishes the accuracy of the measuring device. Rather than accept the measurement
from the device, it is usually best to make at least a simple calibration check to be sure of the
validity of the measurements. The typical calibration cycle required for this device is twelve
months. However, the user’s application environment and performance criteria could dictate that
a more frequent calibration cycle be used to ensure system performance in a particular
application. The final calibration interval is left to the discretion of the end user of the device.
Dimensional
Calibration is a means to verify that system output relates to some known physical displacement,
Standards a reference or dimensional standard with a known degree of accuracy. When choosing a
dimensional standard, keep in mind that accuracy of the dimensional standard has a direct effect
on accuracy of calibration, and thus on the accuracy of any measurements you take.
A micrometer fixture is available from Kaman Precision Products for use as a dimensional standard
repeatable to within 100 micro inches (.0001"). The micrometer has a non-rotating spindle with
an attached target. It is suitable for use with all Kaman sensors up to 2S (up to 8C with a larger
target) and may be rigidly mounted.
For some applications (i.e. larger sensors) nonconductive phenolic or ceramic spacers can be used
in calibration. Ceramic spacers are available from Kaman in sizes ranging from .025” (.635mm)
to 1.000" (25.4mm).
Offset Offset is the minimum space or gap between the sensor and target. You should position your
sensor so that the target never enters this area. When offset has not been considered, linearization
of the system can be difficult as the target enters the offset region. The required offset for a given
sensor is typically 10 to 20% of its full-scale measuring range. See the Sensor Specifications
table in Part 3: EQUIPMENT for sensor offsets.
Offset provides clearance for a moving target, preventing sensor/target contact. Contact could
cause sensor damage and contact errors in measurement.
If you need to transfer the sensor from a calibration fixture to an application fixture, maintain the
offset initially used in calibration. The maximum allowable tolerance on repositioning the sensor
is -2% to +5% of the offset. To re-establish offset, note system output when the calibration target
is at minimum displacement (plus offset)— usually 0 Vdc. Remove the sensor from the
calibration fixture and move it to the application fixture. When the system output equals 0.000
Vdc (or other desired voltage) without adjusting the controls, the original offset has been re-
established.