YOKOGAWA ADMAG AXR - 4.4 Grounding Connection

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4-4
IM 01E30D01-01EN
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
F0407.ai
Figure 4.4.1 Functional Grounding Terminal
Location(General-purposeUse/
Explosion Proof Type except TIIS)
Class A grounding
terminal
Grounding
terminals
F0408.ai
Figure 4.4.2 Functional Grounding Terminal
Location (TIIS Explosion Proof Type)
IMPORTANT
Improper grounding can have an adverse effect
ontheowmeasurement.Ensurethatthe
instrument is properly grounded.
Theelectromotiveforceofthemagneticowmeter
is minute and it is easily affected by noise, and
the reference electric potential is the same as that
ofthemeasuringuid.Therefore,thereference
electricpotential(terminalpotential)oftheowtube
and converter also need to be the same as that of
themeasuringuid.Moreover,thepotentialmustbe
thesameastheground.Themagneticowmeter
is equipped with a grounding ring that makes a
connectionwiththechargeofthemeasureduid
forgroundingandprotectsthelining.Theowmeter
shouldbegroundedbycertainspecications
(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owmetermeasurestheowincorrectly
becausethereferenceelectricalpotentialisoating.
Moreover, grounding is also mandatory in the
simultaneous outputs of current and pulse. If not,
theowmetercausesalargemeasurementerror
because the outputs interfere with each other.