Keller Acculevel - Installation Guidelines; Supply Voltage Requirements; Transmitter Anchoring

Keller America Inc User’s Guide Rev. 07/19
Keller America Inc User’s Guide Rev. 07/19
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.
Someapplicaonsrequirethetransmiertobesuspendedwithoutaprotecveslling
wellorconduitaachment.Inallinstallaons,careshouldbetakentopreventdamage
tothesubmersiblecable.
Transmier Submersion -Damagetosubmersiblecablecanleadtofailureofthetrans-
mier.Kelleremploysaruggedcablejacketmaterialstominimizetheriskofcutsand
abrasion.Sll,takecarewhenloweringyourtransmierintothewell,makingsurethe
cabledoesnotdragoversharpedges.Avoiddroppingthetransmierfromthesurface.
Donotsubmergeelectricalconneconendofcable.
Condensaon protecon -Kellerhasopmizedthesizeofthecableventtominimize
theoccurrenceofwatervaporincursion.Inareasofhighhumidity,itmaybedesirable
touseaDryingTubeAssembly(desiccant)orBellowsAssemblytopreventwatervapor
fromenteringtheventtube.ContactKellerAmericafororderinginformaon.
Bending of Cable-Ourjacketedcableisquiteexible.However,caremustbetakento
ensuretheventtubeintegraltothecableisnotcrimpedwhenbendingthecabletosuit
yourinstallaon.Itisrecommendedthatthecablenotbebenttoaradiussmallerthan
1inch.
Cable Compression -Manyusersemployacompressionngtosecureourcableasit
entersajunconbox.Caremustbetakenthatthengisnotoverghtened,causing
damage to the cable and/or crimping the vent tube.
Page7
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(800)343-1001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
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.
Page6
Total Loop
Impedance
Indicator
Analog Input
Device
Cable
Resistance
IS Barrier
4 - 20mA output
Level / Pressure
Transmitter