Proline Promag 53 PROFIBUS DP/PA
Wiring
Hauser
67
Plastic or insulated lined pipes
Normally, potential is matched using the reference electrodes in the measuring tube. However, in
exceptional cases it is possible that, due to the grounding plan of a system, large matching currents
flow over the reference electrodes. This can lead to destruction of the sensor, e.g. through
electrochemical decomposition of the electrodes. In such cases, e.g. for fiberglass or PVC piping, it
is recommended that you use additional ground disks for potential matching.
Mounting of ground disks
"
Caution!
• Risk of damage by electrochemical corrosion. Note the electrochemical series if the ground disks
and measuring electrodes consist of different materials.
• Also, observe company-internal grounding guidelines.
a0004377
Fig. 40:
Potential matching/ground disks with plastic pipes or insulated lined pipes
Pipes equipped with cathodic protection
In such cases, install the measuring device without potential in the piping:
• When installing the measuring device, make sure that there is an electrical connection between
the two piping runs (copper wire, 6 mm
2
).
• Make sure that the installation materials do not establish a conductive connection to the
measuring device and that the installation materials withstand the tightening torques applied
when the screws are tightened.
• Also comply with the regulations applicable to potential-free installation.
a0004378
Fig. 41:
Potential matching and cathodic protection
1
Isolation transformer Power supply
2
Electrically isolated
6 mm² Cu
6 mm² Cu
1
2
2
