Beckhoff ELX3351, Руководство по эксплуатации

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Basic function principles
ELX3351 29 Version: 1.3.1
Structure of a load cell with a strain gauge
One application of the strain gauge is the construction of load cells.
This involves gluing strain gauges (full bridges as a rule) to an elastic mechanical carrier, e.g. a double-
bending beam spring element, and additionally covered to protect against environmental influences.
The individual strain gauges are aligned for maximum output signals according to the load direction (2 strain
gauges in the elongation direction and 2 in the compression direction).
Fig. 23: Example of a load cell
The most important characteristic data of a load cell
Note
Characteristic data
Please enquire to the sensor manufacturer regarding the exact characteristic data!
Nominal load E
max
Maximum permissible load for normal operation, e.g. 10 kg
Nominal characteristic value mV/V
The nominal characteristic value 2mV/V means that, with a supply of U
S
=10 V and at the full load E
max
of the
load cell, the maximum output voltage U
D
= 10 V * 2 mV/V = 20 mV. The nominal characteristic value is
always a nominal value – a manufacturer’s test report is included with good load cells stating the
characteristic value determined for the individual load cell, e.g. 2.0782 mV/V.
Minimum calibration value V
min
This indicates the smallest mass that can be measured without the maximum permissible error of the load
cell being exceeded [RevT].
This value is represented either by the equation V
min
= E
max
/ n (where n is an integer, e.g. 10000), or in % of
E
max
(e.g. 0.01).