Potential Matching; Standard Case - Endress+Hauser PROFI BUS Proline Promag 53 PROFIBUS DP Operating Manual

Proline Promag 53 PROFIBUS DP/PA
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Endress+Hauser
4.4

Potential matching

4.4.1

Standard case

Perfect measurement is only ensured when the medium and the sensor have the same electrical
potential. Most Promag sensors have a standard installed reference electrode, which guarantees the
required potential matching. This usually means that additional potential matching measures are
unnecessary.
Promag W:
Reference electrode is standard
Promag P:
• Reference electrode is standard for electrode materials 1.4435, Alloy C-22 and tantalum.
• Reference electrode is optional for electrode material Pt/Rh.
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 matched (→ Page 42). Ground rings can be ordered separately as accessories
from Endress+Hauser. → Page 133
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.
Fig. 38: Potential matching by means of the transmitter's ground terminal
Caution!
For sensors without reference electrodes or without metal process terminals, carry out potential
matching 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.
Wiring
a0004375
65