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2.1 Instructions for use of strain gauge sensors
Notice:
Strain gauge sensors with a small range are extremely sensitive to improper handling. Force
transducers can be destroyed simply by touching. Same applies for the diaphragms of pressure transducers.
So, bear in mind: handle with care!
Loading the transducer in excess of the nominal range may result in an increased and lasting zero balance
offset as well as damage to the sensor. The same applies to short-term force or pressure impulses that
exceed the nominal range.
To most force transducers the force must be applied centrically in order to avoid shear forces, that may be
harmful to the sensor, or may cause measurement inaccuracy. Centric force transmission can be ensured
by rounded surfaces, joint heads or other suitable guides.
Tightening torques while mounting any sensors may result in an increased zero balance offset.
If the sensor has been replaced, the calibration of the amplifier must be checked. A new adjustment might
be necessary.
3 Technical description
The described single channel measuring amplifier serves to supply one to 4 parallel connected strain
gauge sensors with each a resistance of 300 Ohms or more and the amplification of the sensor signals.
The supply voltage of the amplifier is galvanically isolated from analogue output, sensor supply and sensor
signal.
The circuitry is in 4-wire technology. Standard analogue outputs are available for further evaluation. The
amplifier is built in a robust aluminum die cast housing, which is suited for rough and industrial
environment.
The coarse amplification is determined by an internal resistor and can be fine adjusted by a potentiometer.
After opening the lid, the potentiometer mentioned before as well as the potentiometer for zero-
adjustment allow a correction of the calibration. In addition, a dip-switch allows to change the width of the
zero-adjustment range. If even this expansion of the range should not be sufficient, an internal resistor
can be soldered in to add a tare.
In addition the amplifier allows, in combination with option “2G”, the monitoring of the signal with 2 freely
adjustable and potential-free relays.