Structure And Mode Of Operation; Transducer; Strain Gage Covering Agent; Inline Amplifier - HBM C9C Mounting Instructions

Structure and mode of operation

4 Structure and mode of operation
4.1

Transducer

The measuring body is a steel loaded member on which strain gages (SG) are
installed. The influence of a force deforms the measuring body, so there is
deformation in places where the strain gages are installed. The SG are
attached so that two are stretched and two are compressed when a force is
applied. The strain gages are wired to form a Wheatstone bridge circuit. They
change their ohmic resistance in proportion to their change in length and so
unbalance the Wheatstone bridge. If there is an excitation voltage, the circuit
produces an output signal proportional to the change in resistance and thus
also proportional to the applied force. The strain gage arrangement is chosen
to compensate, as much as possible, for parasitic forces and moments (e.g.
lateral forces and eccentricity influences), as well as the effects of temperature.
4.2

Strain gage covering agent

To protect the SG, the force transducers have thin cover plates that are welded
on the bottom and, in versions with a nominal (rated) force of up to 200N, on
the top. This method offers very good protection against environmental
influences so that the C9C achieves protection class IP67. In order to retain
the protective effect, these plates must not be removed or damaged in any
way.
4.3

Inline amplifier

The sensors can optionally be ordered with an inline amplifier. This amplifier
module supplies the bridge circuit of the sensors with a suitable supply voltage,
and converts the small output signal of the force transducers with low noise
into a 0 ... 10 V voltage signal (VA1) or a 4 ... 20 mA current signal (VA2). The
delivery is then carried out as a measurement chain, and the test record
describes the correlation between the force input quantity and the output signal
in V or mA.
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A03729_03_YI0_01 HBM: public
C9C