MTS Axial Extensometers - Manual (Page 49)

Calibration 49
3. Adjust compression.
A. Remove the zero pin, fixture, or release the zero stop.
B. Adjust the calibrator between zero and 100% compression of
the extensometer's full-scale range three times. This exercises
the extensometer to remove any hysteresis.
C. Adjust the calibrator for the 80% compression setting (or the
range being calibrated) and note the voltmeter reading.
• If the meter reading is less than -8 V DC you can adjust gain.
Adjust the gain control to set the extensometer signal to
-8 V DC (or 80% of your calculated output).
• If you cannot adjust the gain control to set the extensometer
signal to -8 V DC, you can change the excitation voltage.
4. Readjust the zero and compression.
Repeat Step 2 and Step 3 until the zero and gain outputs can be
measured without readjustment.
5. Adjust tension.
A. Adjust the calibrator between zero and 100% tension of the
extensometer’s full-scale range three times. This exercises the
extensometer to remove any hysteresis.
B. Adjust the calibrator for 80% tension (or for the maximum
positive travel) of the range you are calibrating. Note the
meter reading.
• If the extensometer signal is above +8 V DC (or your
calculated output), adjust the
Δ K (delta K) control for an
extensometer signal of +8 V DC.
• 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).