MTS Axial Extensometers - Manual (Page 46)

Calibration 46
• If the extensometer signal is below +8 V DC (or your
calculated output), the
Δ K adjustment cannot be made. Return
the Δ K adjustment to its original setting and use the gain
control to increase the voltage halfway from its present value
to +8 V DC (this splits the difference between compression
and tension).
How to Use a Calibration Block
MTS recommends using a calibration block to establish the initial gain
setting of the conditioner. The calibration block is a metal block with
grooves cut into it. The grooves allow you to adjust the gain for specific
displacements. The calibration block is usually provided by the
manufacturer of the extensometer. Use this procedure as a guideline to
calibrate other extensometers.
1. Set up the controller.
Your test controller must be configured to use the extensometer
signal.
A. Connect the extensometer to your controller.
B. Monitor the excitation voltage.
C. Monitor the extensometer signal.
D. Prepare to use the calibration controls on your controller.
E. Adjust the excitation control to set the excitation to +6 V DC
or the voltage specified in the extensometer documentation.
2. Zero the conditioner output.
The arms of the extensometer must be in the zero reference
position. Depending on the extensometer, this can be accomplished
using the zero pin, stop block, or a special fixture.
Adjust the zero control to set the extensometer signal to 0.00 V
DC.
Note Several extensometers have asymmetrical outputs. This means
that the compression and tension outputs are not equal. Ensure
that you are aware of the maximum ratings of the extensometer
you are calibrating.
3. Adjust compression.