Proline Promag 55 PROFIBUS PA
Wiring
Hauser
51
4.5
Potential equalization
4.5.1
Standard case
Perfect measurement is only ensured when the medium and the sensor have the same electrical
potential. Most Promag sensors have a reference electrode installed as standard, which guarantees
the required potential equalization. This usually means that additional potential equalization
measures are unnecessary.
Promag S:
• Reference electrode is standard for electrode materials 1.4435/SS 316L, Alloy C-22, tantalum,
Duplex, tungsten carbide coating (for electrodes made of 1.4435)
• Reference electrode is optional for electrode material platinum/rhodium 80/20.
• Reference electrode not present in measuring tubes with a lining made of natural rubber
Promag H:
• No reference electrode. The metallic process connection provides a permanent electrical
connection to the fluid.
• If the process connections are made of a synthetic material, ground rings have to be used to ensure
that potential is equalised (see Page 31). Ground rings can be ordered with the main product
structure or as accessories
!
Note!
For installation in metal pipes, it is advisable to connect the ground terminal of the transmitter
housing to the piping. Also, observe company-internal grounding guidelines.
a0004375
Fig. 35:
Potential equalization by means of the transmitter's ground terminal
"
Caution!
• For sensors without reference electrodes or without metal process connections, carry out
potential equalization as per the instructions for special cases described below. These special
measures are particularly important when standard grounding practice cannot be ensured or
extremely strong matching currents are expected.
• As sensors with a natural rubber lining do not have a reference electrode, ground disks must be
installed if necessary to ensure sufficient potential equalization to the fluid. This applies in
particular to ungrounded metal pipes
