Siemens SIWAREX WL200 Series Operating Instructions Manual page 28

Commissioning
6.2 Application planning
Parallel connection of load cells
In weighing systems, one or more load cells are connected to a weighing module for
evaluation of the measured signal. Several load cells of a scale are connected in parallel to a
junction box to supply a joint output signal.
NOTICE
Overloading of load cells
When more than one load cell is connected to a scale, if the load distribution is uneven, it
cannot be established whether individual load cells are overloaded.
Note
Measurement errors
Load cells are only permitted to be connected in parallel when they have the same
characteristic value, the same rated load and the same internal resistance.
The total resistance of load cells connected in parallel must not undershoot the minimum
resistance from the technical data of the weighing module to which it should be connected.
The maximum number of load cells that can be connected to a weighing module depends on
the total resistance of the load cells connected in parallel. This must lie within the load
resistance limits specified for the weighing module.
The maximum length of the cables and the specifications for other components, e.g. Ex i
interface, must also be complied with. For details, see the section Lengthening and
shortening the connecting cable (Page 31)
Environmental requirements at the mounting location
The foundations must be unyielding when the expected loads are applied. The maximum
roughness permitted for the mounting surface is 1.6 µm.
The values specified in the technical data for the ambient conditions must be complied with.
Note
Measurement errors
The load cell must be protected against direct solar radiation. Otherwise, the permissible
operating temperature may be exceeded. One-sided heating will result in less accurate
measurements or even measurement errors.
28
Operating Instructions, 07/2016, A5E02199611B-03
SIWAREX WL200