User Guide

Keller America Inc User’s Guide Rev. 02/22
Keller America Inc User’s Guide Rev. 02/22
isnotsucienttosupply22.5mAtothecircuit,thenthemaximumpossiblecurrentwill
beseenontheanalogoutput,e.g.,17mA,andthetransmierwillnotiniatenormal
operaon.
Thebenetofthistechnologyisthattotalloopimpedanceisaccountedforpriorto
placingtheequipmentintoservice,prevenngfalseindicaonswhenthevoltagesupply
isinsucienttosupporttheloopwithmaximumpressureapplied.
Mostcurrentloopscontainanaloginputdevices,indicatorsorothercomponentshaving
inputimpedanceswhichmustbeconsideredwhencalculangthesupplyvoltagesneed-
ed.Forexampleananaloginputdevicewitha250OhmInputImpedancewillrequire
anaddionalvoltageof5.5VDC(250x0.022=5.5)inaddiontotheminimumsupply
voltagenecessaryforthetransmiertooperateproperlyovertheenrerange.
Thecalculaonsbelowareusefulinidenfyingtheminimumsupplyvoltageneededfor
acurrentloopwithaddionallineimpedancesorconversely,themaximumcurrentloop
impedanceallowedforagivensupplyvoltage.
 Minimumsupplyvoltagewithlightningproteconoponinstalled:
  11VDC+(Totalloopimpedancex0.022)
 Minimumsupplyvoltagewithoutlightningproteconoponinstalled:
  8VDC+(TotalloopImpedancex0.022)
 Maximumallowableloopimpedancewithlightningproteconopon
 installed:
  (SupplyVDC–11VDC)/0.022
 Maximumallowableloopimpedancewithoutlightningproteconopon
 installed:
  (SupplyVDC–8VDC)/0.022
Transmier Anchoring-ItisrecommendedthatKELLERsubmersibletransmiersbe
installedinasllingwelloraachedtorigidconduitviaaconduitngintegraltothe
transmier,inordertopreventdamagetothetransmierfromimpactwithimmovable
objects.Itisnotadvisabletoethetransmiertoapumportopiping,asanyproblem
withthetransmiercouldrequirethatthepumpbepulledfromtheinstallaon.
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Terminaon Enclosure-Convenientoponcomplemennggauge-typepressure/level
transmiers,whereitisdesiredtoterminatethetransmiercableclosetothemea-
surementpoint.ItincludesaNEMA4Xclearfrontenclosure(7.9X4.7X3.5inches)with
two,liquid-ghtcablengs(onein,oneout),aterminalstrip,andampleroomfor
mounngadryingtubeorbellowsassembly.
Stabilizing Weight-ZincpropshaanodeadaptedtotØ21mmO.D.ofLevelgage,
Acculevel,andLevelRatsubmersibleleveltransmiers.Aidsincorrosionresistanceas
wellashelpsensurethatthecableremainstautinturbulentcondions.
Protecve Spacer-BuiltfortheKELLER’sLevelRatwastewaterleveltransmier,the
protecvespaceranchorstheLevelRatinplacewhileposioningthesensingdiaphragm
otheboomtoavoidfalsereadingscausedbysludgeanddebris.
Cable Hanger-Singleeyefor0.230”diametercablethatgripsthecablejacketand
provideasuspensionpointforinstallaonofcabledtransmiers.
Pressure Test Adapters -Facilitatescalibraonandmaintenancetesng,thesespecialty
adaptersallowforconneconofthevariousKELLERleveltransmierstoapressure
calibrator.
Digital Display / Meter -TheTRIDENTdisplaybyPrecisionDigitalisaversaleandcost
eecveprocessmeterprovidinganeasytouseandreaddisplay/controllerforyour
levelandpressuremeasurementapplicaon.Formoreinformaonandtechnicalsup-
port,pleasecontactPrecisionDigitalat[phone]oronlineatwww.predig.com.
VII. Installaon:
Thefollowingisimportantinstallaonandgeneralmaintenanceinformaonforsub-
mersibletransmiers.PleasecontactKELLERAmericaforaddionalinstrucon.
Supply Voltage-Adequatesupplyvoltageiscricaltoensureproperoperaonof4-20
mApressureandleveltransmiers.Withouttheminimumrequiredvoltageavailableat
thetransmier,thetransmierwillnotoutputthecorrectanalogvalue.
Manyanalogtransmierswillappeartooperateproperlyevenwhenthesupplyvoltage
isnotadequatetopowertheloopwhenthetransmiershouldbeoutpung20mA.
Forexample,a10voltsupplymayappeartobeenoughtopowerananalogtransmier
whenitisoutpung4mAwithzeropressureapplied,butasthetransmier’soutput
increaseswithincreasingpressure,voltagedropsacrossotherdevicesintheloop(ana-
loginputdevices,cableand/orexternalbarrierdevices)mayreducethesupplyvoltage
tothetransmierandpreventitfromprovidingthecorrectoutputaboveacertaininput
pressure/levelthreshold.
KELLERAmerica’s4-20mApressureandleveltransmiersfeaturemicroprocessorbased
signalcondioning.Duringpowerup,thecircuitperformsachecksequencewhichde-
termineswhetherthereissucientsupplyvoltagetopoweralldevicesontheloop,by
sengtheoutputto~110%ofthemaximumvalue,i.e.,~22.5mA.Ifthesupplyvoltage
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Total Loop
Impedance
Indicator
Analog Input
Device
Cable
Resistance
IS Barrier
4 - 20mA output
Level / Pressure
Transmitter