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National Instruments Corporation
29
SCC-SG Series Strain-Gauge Modules User Guide
•
Compensates for the aggregate effect on the principle strain
measurement due to the Poisson’s ratio of the specimen material.
•
Compensates for lead resistance.
•
Sensitivity at 1000
µε
is
∼
1.3 m
V
OUT
/
V
EX
input.
•
Used with the SCC-SG04/24.
Signal Conditioning
The SCC-SG
XX
modules all contain some form of signal conditioning.
This signal conditioning can greatly increase the accuracy of your
measurements. The types of signal conditioning provided by the
SCC-SG
XX
are:
•
filtering
•
amplification
•
excitation
•
bridge completion
•
offset nulling adjustment
•
shunt calibration
Refer to the
, and
Shunt Calibration Using the SCC-SG11
sections
for more information about each type of signal conditioning.
Filtering
Each channel on the SCC-SGO
X
and SCC-SG24 has an output lowpass
filter. The filter is a single-pole, buffered RC filter with a cutoff frequency
of 1.6 kHz.
Amplification
Each channel on the SCC-SG0X and SCC-SG24 has an isolation amplifier
with a gain of 100. This amplifier improves signal measurements by
boosting strain measurements, typically approximately
±
100 mV, to levels
closer to the operating range of DAQ devices, usually
±
10 VDC.
Excitation
The SCC-SG0
X
and SCC-SG24 contain a single onboard voltage source
for bridge configuration excitation. On the SCC-SG0
X,
the
onboard-reg2.5 VDC excitation source supplies up to 42 mA,
which is enough to drive two 120
Ω
bridge configurations. The SCC-SG24
has an onboard-reg10 VDC excitation source that supplies up to
60 mA, which is enough to drive two 350
Ω
bridge configurations.
