<4. WIRING>
4-4
IM 01E30D01-01EN
4.4 Grounding Connection
IMPORTANT
• IncaseofGeneral-purposeUse,grounding
resistanceof100Ωorlessisnecessary.
When the optional code A is selected,
groundingresistanceof10Ωorlessshallbe
required.
• IncaseofTIISexplosionprooftype,
groundingresistanceof10Ωorlessis
necessary for class A grounding terminal.
Groundingresistanceof100Ωorlessis
necessary for Functional grounding terminal.
When the optional code A is selected,
groundingresistenceof10Ωorlessis
necessary for Functional grounding terminal.
• ForexplosionprooftypeexceptTIIS,follow
the domestic electrical requirements as
regulated in each country.
Grounding terminals
F0407.ai
Figure 4.4.1 Functional Grounding Terminal
Location(General-purposeUse/
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
ontheowmeasurement.Ensurethatthe
instrument is properly grounded.
Theelectromotiveforceofthemagneticowmeter
is minute and it is easily affected by noise, and
the reference electric potential is the same as that
ofthemeasuringuid.Therefore,thereference
electricpotential(terminalpotential)oftheowtube
and converter also need to be the same as that of
themeasuringuid.Moreover,thepotentialmustbe
thesameastheground.Themagneticowmeter
is equipped with a grounding ring that makes a
connectionwiththechargeofthemeasureduid
forgroundingandprotectsthelining.Theowmeter
shouldbegroundedbycertainspecications
(groundingresistanceof100Ωorless,or10Ωor
less) according to Figure 4.4.3.
Grounding is mandatory especially for insulated
piping such as PVC-sheathed pipes. If not, the
magneticowmetermeasurestheowincorrectly
becausethereferenceelectricalpotentialisoating.
Moreover, grounding is also mandatory in the
simultaneous outputs of current and pulse. If not,
theowmetercausesalargemeasurementerror
because the outputs interfere with each other.