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Edition 06/2009
At least four WSGs per load cell are connected in a full Wheatstone bridge. The
stretched or upset WSGs are wired so that the positive or negative changes in
resistance add up to a total upset of the bridge.
The feed voltage (in 6-wire technology also the sensor voltage, SENSE) is applied
at one bridge diagonal. The measuring voltage is tapped at the other diagonal.
At a constant feed voltage (EXC), the measured voltage (SIG) changes
proportionally to the applied load (figure 1-2). In practice load cells contain other
resistors for temperature compensation, zero point and parameter adjustment.
These may be in the input or output of the load cell depending on the type and on
requirements.
Figure 1-2 Principle diagram of a Wheatstone bridge
The SIWAREX R load cells are usually made of high-grade steel and are welded
hermetically sealed. This provides high corrosion protection and protection rating.
Most series are licensed for use in scales with mandatory calibration of class III
according to DIN EN 45501 and comply with OIML R60 3000d. Load cells with
greater accuracy and/or EEx (i) approval are available on request.
SIWAREX R load cells are electrically calibrated as standard. As a result, no
reference load adjustment is necessary for example when commissioning a
platform scales. A load cell can also be exchanged without readjustment.
An exception to this rule is the series K and possibly load cells delivered outside
the standard scope of delivery. The respective technical data apply for these load
cell types.
SIWAREX R Load Cells Operating Manual
A5E00159640
Technical Description
6
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