Endress+Hauser Proline Promag 51, Руководство по эксплуатации

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Proline Promag 51 4 Wiring
Hauser 49
Plastic pipes and isolating 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 fibre-glass or PVC piping,
it is recommended that you use additional ground disks for potential matching (Fig. 36).
Mounting of ground disks
→
Page 29, 33
"
Caution!
• Risk of damage by electrochemical corrosion. Note the electrochemical insulation rating,
if the ground disks and measuring electrodes are made of different materials.
• Also, observe company-internal grounding guidelines.
F06-5xxxxxxx-04-xx-xx-xx-004
Fig. 36: Potential equalisation/ground disks with plastic pipes or lined pipes
Lined pipes (cathodic protection)
In such cases, install the measuring instrument 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 measur-
ing device and that the installation materials withstand the tightening torques applied when the
threaded fasteners are tightened.
• Also comply with the regulations applicable to potential-free installation.
F06-5xxxxxxx-04-xx-xx-xx-005
Fig. 37: Potential equalisation and cathode protection
1 = isolating transformer power supply, 2 = electrically insulated