Grounding Connection - YOKOGAWA ADMAG AXR User Manual

4.4

Grounding Connection

IMPORTANT
• In case of General-purpose Use, 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.
When the optional code A is selected,
grounding resistence of 10 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
Figure 4.4.1 Functional Grounding Terminal
Location (General - purpose Use/
Explosion Proof Type except TIIS)
F0407.ai
<4. WIRING>
Class A grounding
terminal
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 4.4.3.
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.
4-4
Grounding
terminals
F0408.ai
IM 01E30D01-01EN