Section 7. Installation
adjusted gage factor (GF
adj
), which is then used as the gage factor in
StrainCalc()
. GF is stored in the CAL file and continues to be used in
subsequent calibrations. Non-linearity of the bridge is compensated for by
selecting a shunt resistor with a value that best simulates a measurement near
the range of measurements to be made. Strain-gage manufacturers typically
specify and supply a range of resistors available for shunt calibration.
3. Shunt calibration verifies the function of the CR1000.
4. The zero function of
FieldCalStrain()
allows a particular strain to be set as an
arbitrary zero, if desired. Zeroing is normally done after the shunt calibration.
Zero and shunt options can be combined ina single CRBasic program.
CRBasic example
FieldCalStrain() Calibration
(p. 225)
is provided to demonstrate
use of
FieldCalStrain()
features. If a strain gage configured as shown in figure
Quarter-Bridge Strain-Gage with RC Resistor Shunt
(p. 225)
is not available, strain
signals can be simulated by building the simpl
e circuit, substituting a 1000 Ω
potentiometer for the strain gage. To reset calibration tests, use the support
software
File Control
(p. 515)
menu to delete .cal files, and then send the
demonstration program again to the CR1000.
Ex
ample Case: A 1000 Ω strain gage is placed into a resistive bridge at position
R1. The resulting circuit is a quarter-bridge strain gage with alternate shunt-
resistor (Rc) positions shown. Gage specifications indicate that the gage factor is
2.0 and that w
ith a 249 kΩ shunt, measurement should be about 2000 microstrain.
Send CRBasic example
FieldCalStrain() Calibration
(p. 225)
as a program to a
CR1000 datalogger.
7.9.12.6.2 Field Calibration Strain Examples
CRBasic example
FieldCalStrain() Calibration
(p. 225)
is provided to demonstrate
use of
FieldCalStrain()
features. If a strain gage configured as shown in figure
Quarter-Bridge Strain-Gage with RC Resistor Shunt
(p. 225)
is not available, strain
signals can be si
mulated by building the simple circuit, substituting a 1000 Ω
potentiometer for the strain gage. To reset calibration tests, use the support
software
File Control
(p. 515)
menu to delete .cal files, and then send the
demonstration program again to the CR1000.
Case
: A 1000 Ω strain gage is placed into a resistive bridge at position R1. The
resulting circuit is a quarter-bridge strain gage with alternate shunt-resistor (Rc)
positions shown. Gage specifications indicate that the gage factor is 2.0 and that
with a 249 kΩ shunt, measurement should be about 2000 microstrain.
Send CRBasic example
FieldCalStrain() Calibration
(p. 225)
as a program to a
CR1000 datalogger.
224
Summary of Contents for CR1000
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Page 457: ...Section 8 Operation 8 8 1 3 Final Memory Tables Figure 119 Final Memory Tables 457 ...
Page 458: ...Section 8 Operation 8 8 2 Run Stop Program Figure 120 Run Stop Program 458 ...
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Page 461: ...Section 8 Operation 8 8 4 PCCard Memory Card Display Figure 123 PCCard CF Card Display 461 ...
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