Yokogawa ADMAG AXR - Manual (Page 28)

<4. WIRING>
4-4
IM 01E30D01-01EN
4.4 Grounding Connection
IMPORTANT
Grounding resistance of 100 Ω or less is
necessary. When the optional code A is selected,
grounding resistance of 10 Ω or less shall be
required.
In case of TIIS explosion proof type, grounding
resistance of 10 Ω or less is necessary for class
A grounding terminal.
Grounding resistance of 100 Ω or less is
necessary for Functional grounding terminal.
For explosion proof type except TIIS, follow the
domestic electrical requirements as regulated in
each country.
Grounding terminals
F0407.ai
Figure 4.4.1 Functional Grounding Terminal
Location (General - purpose Use/
Explosion Proof Type except TIIS)
Class A grounding
Grounding
terminal
F0408.ai
Figure 4.4.2 Functional Grounding Terminal
Location (TIIS Explosion Proof Type)
IMPORTANT
Improper grounding can have an adverse effect
on the flow measurement. Ensure that the
instrument is properly grounded.
The electromotive force of the magnetic flowmeter
is minute and it is easily affected by noise, and
the reference electric potential is the same as that
of the measuring fluid. Therefore, the reference
electric potential (terminal potential) of the flowtube
and converter also need to be the same as that of
the measuring fluid. Moreover, the potential must be
the same as the ground. The magnetic flowmeter
is equipped with a grounding ring that makes a
connection with the charge of the measured fluid
for grounding and protects the lining. The flowmeter
should be grounded by certain specifications
(grounding resistance of 100 Ω or less, or 10 Ω or
less) according to Figure 4.4.2.
Grounding is mandatory especially for insulated
piping such as PVC-sheathed pipes. If not, the
magnetic flowmeter measures the flow incorrectly
because the reference electrical potential is floating.
Moreover, grounding is also mandatory in the
simultaneous outputs of current and pulse. If not,
the flowmeter causes a large measurement error
because the outputs interfere with each other.
F0409.ai
600 V vinyl-insulated cable
(2 mm 2 or larger)
[General - purpose Use/Explosion Proof Type
except TIIS]
• Class D requirements (ground resistance,
100 Ω or less).
Optional code A (lighting protector): Class C
requirements (ground resistance, 10 Ω or less).
• Explosion proof type except TIIS: Domestic
electrical requirements as regulated in each
country.
grounding ring