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FEM630 |
ELECTROMAGNETIC FLOWMETER | OI/FEM630-EN REV. A
6 . . .Electrical connections
. . .Sensor grounding
Grounding for devices with protective plates
The protection plates are used to protect the edges of the
meter tube liner, e.g. for abrasive media.
In addition, the protection plates function as a grounding
plate.
• For plastic piping or piping with insulating liner,
electrically connect the protection plate in the same
manner as a grounding plate.
Grounding with conductive PTFE grounding plate
Grounding plates made of conductive PTFE are optionally
available for nominal diameter ranges of 3/8” to 10” (DN 10 to
250). These are installed similar to conventional grounding
plates.
Devices with extended diagnostic functions
For devices with extended diagnostic functions different
installation conditions may be valid.
For additional information, see
Extended diagnostic
functions
on page 117.
Installation and grounding in piping with cathodic
corrosion protection
The installation of electromagnetic flowmeters in systems
with cathodic corrosion protection must be made in
compliance with the corresponding system conditions. The
following factors are especially important:
1
Pipelines inside electrically conductive or insulating.
2
Piping consistently and widely on cathodic corrosion
protection potential. Or mixed systems with ranges on
cathodic corrosion protection potential and ranges on
functional ground potential.
– In the case of pipes free from stray current and
insulated on the inside with liner, the sensor should be
installed in the piping insulated with grounding plates
(upstream and downstream from the sensor). The
cathodic corrosion potential is bypassed around the
sensor. The grounding plates upstream and
downstream of the sensor are connected to functional
ground (Figure 31 / Figure 32).
– If the occurrence of external stray currents is to be
expected in piping with internal insulation (e.g. in the
case of long pipe sections in the vicinity of power
supply units), an uninsulated pipe of approx. ¼ × DN of
length should be provided upstream and downstream
of the sensor in order to deviate these external stray
currents away from the sensor (Figure 33).
