Page 28 of 82
Date: 27.01.06
6.9.1.3.4
Calibration using a shunt resistance
Note:
Shunt calibration is the least accurate technique of the four calibration methods
offered. Only select this option if there are no other means available. This method
can be used quite satisfactorily, however, for occasional electrical checks of the
measuring chain.
Calibration
In this method, a shunt resistance, which can be selected from a menu, is
connected across a bridge resistor of the strain gage full-bridge to deliberately
unbalance the bridge (calibration offset). Find the value of this shunt resistance
and the associated calibration offset from the sensor test certificate and select the
value under the menu option “Channel settings”
Input reference” (see
).
The required shunt resistance is listed under Channel settings.
Enter the “Lower scale value” of the sensor measurement range. Usually this will
be the zero point of the sensor (e.g. 0.0000). This value is assigned to the “Lower
calibration value”. This information can be obtained by teach-in or entered directly
from the test certificate
.
Enter the “Upper scale value” of the sensor measurement range.
Example calculation
Known:
Calibration offset
= 0.8955 mV/V
Calibration resistance = 100 k
Ω
Upper range value x Calibration offset
Upper scale value = --------
----------------------------------
---------
Sensitivity
100 N x 0.8955 mV / V
Upper scale value =
-------------------------------------------------------- = 84.978174 N
1.0538 mV/V
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