IMC C SERIES User Manual page 112

112 Device description
5.8.2 Bridge measurement
Measurement of measurement bridges such as strain gauges. The measurement channels have an
adjustable DC voltage source which supplies the measurement bridges. The supply voltage for a group
eight inputs is set in common. The bridge supply is asymmetric, e.g., for a bridge voltage setting of
VB=5 V, Pin +VB is at +VB=5 V and Pin -VB at -VB=0 V. The terminal -VB is simultaneously the device's
ground reference.
Per default 5 V and 10 V can be selected as bridge supply. As an option the amplifier can be build with
2.5 V bridge supply. Depending on the supply set, the following input ranges are available:
Bridge voltage [V]
10
5
2.5
Fundamentally, the following holds: For equal physical modulation of the sensor, the higher the selected
bridge supply is, the higher are the absolute voltage signals the sensor emits and thus the measurement's
signal-to-noise ratio and drift quality. The limits for this are determined by the maximum available
current from the source and by the dissipation in the sensor (temperature drift!) and in the device
(power consumption!)
·
For typical measurements with strain gauges, the ranges 5 mV/V to 0.5 mV/V are relevant.
·
There is a maximum voltage which the potentiometer sensors are able to return, in other words
max. 1 V/V; a typical range is then 1000 mV/V.
Bridge measurement is set by selecting as measurement mode either Bridge: Sensor or Bridge: Strain
gauge in the operating software. The bridge circuit itself is then specified under the tab Bridge circuit,
where quarter bridge, half bridge and full bridge are the available choices.
We recommend setting channels which are not connected for voltage measurement at the highest
input range. Otherwise, if unconnected channels are in quarter- or half-bridge mode, interference may
occur in a shunt calibration!
© 2018 imc Test & Measurement GmbH
Measurement range [mV/V]
±1000 to ± 0.5
±1000 to ± 1
±1000 to ± 2
Note
imc C-SERIES - Manual, Version 4 R 3 - 2018-10-19