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Cathodically
Protected Metal
Tanks
Cathodically protected metal tanks
are never directly grounded.
However, the impedance of the
supply source is so low that it will
not cause any problems. The
shielding of the loop cable should
be grounded at one end only (the
tank end) to avoid short-circuiting
the cathode protection voltage.
The ground lug on the
SITRANS LC 500 can be connected
to the tank as shown.
(See page 30 for further grounding
details.)
Note:
Grounding the SITRANS LC500 as illustrated above provides only system
grounding for referencing purposes: it does not provide safety grounding.
Non-Conductive Tanks
Non-metallic tanks always require a
stilling well or proper grounded
conductive medium.
Connect the ground lug on the
SITRANS LC 500 to earth ground. If
the stilling well is integral to the
SITRANS LC500, it is now grounded.
If the vessel has a stilling well
provided, make sure that the metal
parts of the stilling well are properly
grounded.
Safety Grounding
The safety grounding requirements are determined by the application and the connected
instruments. The SITRANS LC500 transmitter does not have any special requirements
due to the galvanic separation between the measurement section and the loop section.
Depending on the DCS characteristics, there are three possible grounding options:
Page 32
SITRANS LC500 – OPERATING INSTRUCTIONS
optional stilling
well
metal
stilling well
non-
metallic
ground lug
V
KP
ground lug
7ML19985GE04
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