Lengthening And Shortening The Connecting Cable - Siemens 7MH5102 Operating Instructions Manual

6.2.3

Lengthening and shortening the connecting cable

Load cells can be equipped with connecting cables with four or six cores.
Note
Measurement errors
Connecting cables are only permitted to be extended using electro-magnetically compatible
housings, such as the SIWAREX JB junction box.
Single load cells
If a scale is equipped with a single load cell, the scale can be directly connected to the weighing
module if space permits. To bridge longer distances, the connecting cable can be extended using
a junction box.
Several load cells are connected in parallel in a junction box.
Connecting cable in four-wire system
Note
No calibration approval
In scales requiring official calibration, the connecting cables for load cells in a four-wire system
must not be shortened or lengthened.
When the length of the connecting cable is altered, the input and output resistance changes.
This change can be corrected by adjusting the scale, but temperature-dependent resistance
changes are not compensated for the missing or additional length of cable.
The value of the residual temperature error is presented in the diagram below. The investigation
was based on the SIWAREX measurement cable 7MH4702-8AG / -8AF. The supply cables are
connected in parallel (double).
SIWAREX WL200
Operating Instructions, 04/2021, A5E02199611B-12
Commissioning
6.2 Application planning
35