Kaman DIT-5200L - Manual (Page 7)

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Kaman Precision Products PART NO: 860522-001
www.kamansensors.com Last Revised 11/16/2012
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3.2 Sensor Mounting and Installation
The sensors must be securely clamped. A collet type fixture is the best. It is best to clamp the
fixture as close to the sensor face as possible (without causing additional loading on the sensor) –
this is to minimize expansion differences between the two sensor housings. To insure that the
fixturing does not load the sensor and cause performance errors you should have any metal parts
approximately 3 sensor diameters away from the tip.
The target must not strike the sensor face. The sensor should have a null gap and measuring
range specified on the calibration record. As an example a 15N sensor may have a null gap of 15
mils (0.015” / 0.381mm) and a range of +/-10 mils (+/-0.010” / +/-0.254 mm). The difference
between the null gap and measuring range is the offset distance for the sensors. In this example
the offset would be 15-10=5 mils for an offset. The offset is the closest distance the sensor gets
to the target during normal operation. This offset is necessary both to optimize performance and
to keep the target from contacting and possibly damaging the coils in the sensor face.
Install the sensors so that only the target interacts with the sensor’s field. No conductive material
other than the target should be present within the sensor’s field. Because the sensor field
radiates in all directions, excessive back loading can also be a problem.
3.3 Electrical Nulling Procedure
Note: Although both sensors may appear to be positioned mechanically, this can cause a
cumulative error. By electrically positioning the second sensor using the system output, the error
is minimized.
The sensor coil is mounted at the face of both sensors. For purposes of mechanical nulling,
measure distance from the sensor face. (Use care not to damage the sensor coil)
1. Sensor position relative to the target is critical. Make sure the target is in the null position.
Install the first sensor of a pair (start with X-) in the application fixture. Using a dimensional
standard, precisely locate the sensor at the null gap. Secure the sensor and recheck its
position.
2. Now install the second sensor of the pair (X+) in the fixture and position it to within a few mils
(10’s of microns) of the required null gap. Connect the Power/Signal line and apply power to
the system. The system must be energized for a minimum of 30 minutes for best results. Use
the output from the system as a guide in the final positioning of this sensor (electrical nulling).
Slowly move the second sensor toward or away from the target as necessary until the system
output reads 0VDC (typically +/-10mV). Secure the sensor and recheck that the output is
0VDC. This output indicates the sensor is positioned correctly.
3. Repeat steps 1 and 2 for sensor Y- and Y+.
The system is now ready for use.