AVI AVI-PDU Series User manual

Installationand
OperatingInstructions
SeriesAVI-PDU
RFDRIVENSHIELDLEVELSWITCH

1
GeneralSafetyNotes
1. Forpersonneland equipmentsafety,pleaseusecarewhenliftingand installing
equipment.Totalweightabout5kgorhigherwithcertainlongercableprobesand
over15 kg withflanges.
2. Beawareofthepowerand relay wiringwhendoingcalibrationormaintenance as
highvoltagecanexistontheseconnections.
3. Pay attentionto unsafeconditionswheninstalling theequipmentinthefield.

2
SECTION1INTRODUCTION
1.1SystemDescription
Thisinstruction manualisfortheAVI-PDU Series smart twowireRFadmittance levellimit switch,whichisusedfor
mostlevelmeasurementsandcontrolandissuitableforalmostall industrialorcivilapplicationswheremeasuringlevelof
liquids,powders,slurries andinterface.Theequipmentcanbeeitherinstalledindoororoutdoor,nospecialmounting
requirementsneeded.
Theequipmentisalevelswitchcomprisedofoneelectronicunit,oneconnectingcoaxialcableand onerigidorcable
sensingelement(and alsoit couldbecalledprobe).These componentscanbeconnectedinanintegralconfiguration ora
remoteconfigurationwhichallelectricalcomponentsaremountedawayfromthemeasuringpointandthesensingelement.The
sensingelementcanbemanufacturedofmanydifferentmetalsand insulatorsdependingonthespecificapplication.See figure
1.1as AVI-PDU series integralsystemscheme.
Figure1.1AVI-PDU series RF levelswitch
TheAVI-PDU series RF levelswitchisstrictlyfollowedtheInternational/Chinese standardswhichlistbelow.
1.2OperationPrinciple
RadioFrequencyadmittance leveltechnologyusesabasiccapacitance technology todetectthedifference inmaterials,i.e.
air/powder,air/liquid,oil/water.Butithas advancedfeatures forrejectingcoatings,morereliableand stableoperation,higher
accuracyand remoteelectronics.
RadioFrequencyadmittance technologyemploysacapacitance bridgeand differsfromcapacitance technologyinthe
electronics;cableandsensingelementuses adrivenshieldcircuittostabilize thecoaxialcable.Theelectronicunit smeasuring
(probe)signalisalsopassedthroughaparallelin-phase amplifierinternally.Thisadditionalsignalisconnectedtotheshieldof
thecoaxialcableand thenispassedtothesensingelement sshieldconnection.Thisdrivenshieldamplifierisanin-phase
amplifierwithagainof1.Thesignalon theshieldhas thesamepotential,phase,andfrequencyas themeasuringsignalbutis
electricallyisolatedfromthemeasuringsignalandmeasuringcircuit.Since thecenterwire&shieldwireofthecoaxialcable
havetheaboverelationship,thereisnopotentialdifference betweenthem.Nopotentialdifference meansthatnocurrentflows
betweentheconductors,and no currentflow(leakage)fromthecenterwiretotheshieldmeansthereisno capacitance between
them(capacitance equalzero.)Asaresult,build-up onthesensor,cablelengthandcabletemperaturehaveno affecton the
measurement.Aseparateground wireconnectstheprobegroundtotheelectronicamplifierground.

3
insulating
material
centerrod
inactive shield
Figure 1.2Sensingelementconstruction
TheRFadmittance technologyeliminates theeffectofbuild-uponthesensingelement(usuallycalledcoating),usinga
fivelayercoaxialconfiguration sensingelement(See figure1.2sensingelementinvessel).Themeasuringelementisthecenter
rod,DrivenShieldisthemiddleelement,and theinactive(ground)istheoutsideelement.Eachelementisisolatedfromeach
otherwithanappropriateinsulation material.Asexplainedinthecoaxialcabledescription,thesame signalsareconnectedto
thesensingelement; centerwiretomeasuringelement, shieldtothedrivenshieldelement, and ground toground.
Weputaspecialcircuit tokeepno potentialdifference betweenthemeasuringelement&shieldelement.Whenthereis
somecoatingon theprobe,theimpedance ofthebuild-upislowand measurablecurrentwill notpass fromthemeasuring
elementtotheshieldorground,i.e.UA=UB,IAB=(UA-UB)*YL=0.Theelectronicunitsoonlymeasures thecurrentbetweenthe
sensingelement&probeground(vesselwall).See figure1.3equivalentsketch.Theshieldtoground (vesselwall) potentialis
difference butthiscurrentisnotpart ofthemeasurementcircuit soit does notaffectthemeasurement.Aproprietaryamplifier
circuit keepsthepotentialonthedrivenshieldelementintrinsicallysafeand inbalancewiththemeasuringcircuit.Withthis
techniquethemeasurementcircuit isnotaffectedbybuild-up on thesensingelement. Onlywhenmaterialinthevesselraises up
totouchthecenterrod(measuringsensingelement) couldmakethecurrentflowthrough thematerialfromthecenterrod to
groundtochangethestateofthealarmloop outputcurrent.
ZAC
IAC easured
cerrent
coating
equivalent
circuit
ZAB
ZBC
material B
C
A
notmeasured UA
UB>IAB<0
coating
1.3Equivalentsketch

4
SECTION2SPECIFICATION:
2.1Systemspecification:
Measuringcircuit terminals:measurementcategoryII,onlyuse theequipmentformeasurementswithinmeasurementcategory
Iand II, transientovervoltageis2500V.
Output:DPDTreply(doublepoledoublethrow)
ContactRating:250VAC:1Ainductive,3Anon-inductive
Powerrequirement:UniversalPowersupply 30~265VAC, 50/60Hz &21~27VDC
Powerconsumption:2W
Resolution:0.2pForlower
Repeatability:<1mm(conductive)
<20mm(insulating)
Loadresistance:Centerwiretoshield500 , Shieldtoground50
Fail safe:High(HLFS)orlow(LLFS)fieldadjustable
Indicators:Red-levelalarm;Green-systemnormal;Yellow-instrumentfailure
AmbientOperatingTemp.(electronics):-40~+75℃(-40~167℉)
StorageTemp.:-40~+85℃(-40~185℉)
Response time:0.5second
Time delay:2~25seconds(continuouslyadjustable)
Barrier:Built-inlimitingcurrent、three-limitingvoltagebarrier
ESDprotection(forunit): 4KV/8KV
SensingElementIL0.5m(19.7”)standard,0.1m(3.9”)~20m(787.4”)optional
InactiveLength:maxlength50m(164 ft); 50m(1968.5”)~100m(3937”)consult factory
Cablelength:5m(197”)standard,0.1m(3.9”)~50m(1968.5”)optional ＞50m(1968.5”)~100m(3937”)consultfactory
ElectricalConnection:doubleM20×1.5(cablediameterlessthan12mm,0.47”),3/4”NPToptional
Process Connection:Standard:BSPTThread, NPTandFlanges optional
Mounting:vertical, horizontaloranyangle
Ingress Protection:accordwithIP67 requirements
Explosion-proofrating:Exd[ia]iaIICT4
Designedelevation altitude:lowerthan2000m(6562ft)

5
SECTION3MODELNUMBER
Probe(sensingelement) specificationsS.E. Mounting
Probes
Numbe
r
IL SHD L/INACTL Wetted
Material
Insula-
tion
Weight
/Anchor
S.E.
Mounting
S.E.Type S.E.Temp.
&Press
Application
18 St.500mm(19.7")
/250mm(9.8")
250mm(9.8")/180mm
(7");80mm(3.1")
/0mm(0")
304SS
(st.)other
optional
PPS NO 3/4"BSPT;
3/4"NPT
optional
OD9mm(0.35")
Threeterminal
rod
100℃/1.0MPa
（212℉/145psi）
25℃/1.6MPa
（77℉/232psi）
Normaltemp.
&pressure
19 St.500mm(19.7")
/250mm(9.8")
250mm(9.8")/180mm
(7");80mm(3.1")
/0mm(0")
316SS PEEK NO 3/4"BSPT;
3/4"NPT
optional
OD9mm(0.35")
Threeterminal
rod
230℃/1.6MPa
（446℉/232psi）
25℃/4MPa
（77℉/580psi）
Mid-
Temperature&
pressure
20 St.500(19.7")
Max2m(78.7")
250mm(9.8")/
180mm(7")
otheroptional
304ss(st.)
other
optional
PTFE NO 2"BSPT;
2"NPT
optional
OD22mm(0.87")
Threeterminal
rod
100℃/1.0MPa
（212℉/145psi）
25℃/1.6MPa
（77℉/232psi）
Heavyduty
anti-agitation
21 04ss(st.)
other
optional
UR NO 170mm*
170mm
(6.7"*6.7")
205mm(8")*
205mm(8")
Threeterminal
flushmounting
82℃/0.2MPa
（180℉/29psi）
25℃/0.5MPa
（77℉/73psi）
Heavyduty
anti-dash
22 St.500mm(19.7")
Max.2m(78.7")
rod;6m(236")cable
250mm(9.8")/180mm
(7")otheroptional
304SS(st)
other
optional
Ceramic
&
copper
NO 11/4"
BSPT;
11/4"NPT
optional
OD9mm(0.35")
Threeterminal
815℃/0.1MPa
（1500℉/15psi）
25℃/2.0MPa
（77℉/290psi）
High
temperature
23 st.2m(787")
Max.8m(315")
cable
250mm(9.8")
/180mm(7")
304SS(st.)
other
optional
PPS Yes 3/4"BSPT;
3/4"NPT
optional
OD9mm(0.35")
Threeterminal
cable
100℃/1.0MPa
（212℉/145psi）
25℃/1.6MPa
（77℉/232psi）
24 Max.3m(118") 304SS(st.)
other
optional
FEP Yes 3/4"BSPT;
3/4"NPT
optional
OD12mm(0.47")
Twoterminal
rod
150℃/2.5MPa
（302℉/363psi）
25℃/4.0MPa
（77℉/580psi）
Smallrange
corrosiveliquid

6
SECTION4INSTALLATION
4.1Unpacking
Carefullyremovethecontentsoftheshippingcarton andcheckeachitemsuchas modelnumber,serialnumberof
electronicunit&sensingelement,accessory,instructionmanualetc.Accordingtothepackinglistwithoutdestroyingany
packingmaterials. Ifthereisanyshortageordamage, contact usorlocalagent, packingmaterialneedn trecycle.
4.2Generalrequirements
TheAVI-PDU series levelsystemcanbemountedvertically,horizontallyoratanangle.Becertainthatneitherthe
measuringelementnorthedrivenshieldelementcontactthevesselwall, nozzleoranyobstruction inthevessel.
Thesensingelementshouldbeinstalledusingaproperthreadsealantandtightenedusingthehexwrenchflatson the
inactive(ground)portionoftheprobe. DO NOTtrytotightentheprobebyusingleverageon theprobehousing, Thehousingor
probesealsmaybedamaged.Forlongrigidsensingelementsinagitatedvesselsasupport shouldbeaffixedtotheinactive
section oftheprobetopreventdamage.Longfullyinsulatedsensorsmaybeanchoredinthevessel.Consulteitherthefactory
orlocalrepresentativeforspecificrecommendations.
Electricalconnectionsshouldconformtoplantandnationalstandards.Forhorizontalmounting,instrumentwireentries
shouldbepointeddownwardtothevesselsomoistureisnotcarriedintotheelectricalhousingthroughtheconduit.
Forexplosion-proofinstallationseachwiringentrymusthaveanappropriategas sealdevice.Consult factoryorlocalrep
forsuchfitting.
Instrumentsinstalledoutdoorsinareas oflightningstrikes shouldbeinstalledwithlightningprotection.
24VDC Instrumentpowernoise shouldbelowerthan200mV.
Groundwireshouldbeconnectedtostandardgroundorinstrumentground, mustn tbeconnectedtodynamicground.
Figure4.1AVI-PDU integralsystemmounting
Powerwireshouldbe3terminalarmaturecable,cableO.D.shouldless than12mm,conductormaterialofthecableis
copper,sectionarea shouldbetween0.13 –2.1mm2(AWG14-26),insulatingcapability1500V.Andshouldmeet
IEC60245/60227standardrequirements.AssociatedswitchshouldmeetIEC60947 requirements.
Please considerdoublepowervoltagecapacitance since theinstrumentconsumptionis 2W.
Very Importantinformation forInstallation:ForExplosive proofand safetyreason, the system
housing shouldbe connectto the earthreliably.

7
4.3IntegralInstallation
TheAVI-PDU series levelswitchisdesignedandsuitableformostindustrialapplications.Themountinglocationofthe
electronicunitshouldfree ofvibration,corrosiveatmospheres,oranypossibilityofmechanicaldamageformaximumservice
life.Ifthisisnotpossible,consideraremoteelectronicsystem.Mostintegralsystemscanbefieldconvertedtoremote
electronicsystem. Consultyourlocalrepoffactoryforaconversionpartslist.
Forconvenience whenadjustingelectroniccontrols,place theelectronicunitinareasonablyaccessiblelocation.Ambient
temperatureshouldbebetween-40~70oC(-40~158oF ).See figure4.1integralsystemmounting.
4.4RemoteInstallation
Aremotesystemseparates theprobefromtheelectronics withaspecialcoaxialcable(providedbyfactory).Thecablecan
befieldshortenedandre-terminatedas required.DO NOTcoil excess coaxcable.ConnecttheCenterwireofthecabletothe
centerwireterminaloftheunit(CW),connectthecoaxialcableshieldtothedrivenshieldterminal(SHD),andthegroundwire
totheGND terminal.Thegroundwireisusuallyanindependentwirepulledwiththecoaxcable.See figure4.2UFI7P01
Remotemounting.
TheXPhousingofelectronicunitcouldbeinstalledon abracketorwall usingthemountingholes provided. See figure4.3
XPhousinginstallation.
Figure4.2AVI-PDU remotesystemmounting
46(1.8")
52(2")
109.5(4.3")
69.5(2.7")
M6
132(5.2") 33.5(1.3") 57.5(2.63")
102(4")
M6
23.5(0.92")
ElectronicunitProbe
Figure4.3XPhousinginstallation

8
4.5SensingElementInstallation
Whenselectinganinstallation point,besurethemeasuring elementwill contact thematerial at thepointthe
alarmshouldbeinitiated.Donotinstalldirectlyunderaflowstreamor feedline.Beawareoftheangle ofrepose
ingranularbinsandsilos,thelevel mustreachtheprobe.Ifasuitable place insidethevessel cannotbefound,
consideranexternal chamberfor liquidmeasurements.Besurethelevel intheexternalbridle tracksthelevel in
thevessel.Payattentiontotheamountofspace abovethevessel,rigidprobesmusthaveadequate head-roomto
install theprobe.
For reliable andtrouble free installationandoperation:
1. Donotdamageor modifytheprobeinsulatorswheninstallingthe instrument/ sensingelement
inthevessel.Besure themeasuring&shieldelementsdo nottouchthenozzleor vesselwall.
2. Donotinstall thesensingelementdirectlyunderaflowstreamor feedline. Ifthisistheonly
positionavailable, use a baffle or shieldabovethe probe tokeepitoutoftheflowstream.
3. Donotopensensingelementor loosensealedgland.
4. Use open-endwrenchonthewrenchflattotightensensingelement. DoNotuse thehousing as
a source ofleverage.
5. Reviewtheinstallationdistancewhenmounting rigidprobe. Keepcableprobeasstraightas
possible toavoidhitting the vesselwall.
6. Longrigidprobesinagitatedvesselsor where excessforce isplacedon theelementshouldbe
supportedusingabracketfromthevesselwall totheinactivesectionoftheprobe. Long
flexible probesshouldbe anchoredusingthefactorysuppliedanchor assembly.
7. Payattentiontomoistureor condensationintheconduit it willcausedamagetoelectronicunit.
8. Connectthe ground of the sensingelementto field equipmentsecurely,less than1ohmresistance.
Consult factoryorrepresentativefornon-metallic vessel groundingrecommendations.
CAUTION: DO NOTUSEADOPTMONO-COMPOSITION ENCAPSULAN
(acetic acidwill decayelectricalcomponent).
USESPECIALDOUBLE-COMPOSITION ENCAPSULAN(non-erosive),
pleaseconsult factoryforthe typeof thismaterial.
4.6Typicalmounting
support
mounting
nozzle
mounting flange
mounting
Nozzle/Flange mounting Insulation Supportmounting

9
Anchormounting Bentmounting
Bracketmounting in open vesselExternalside armmounting

10
15°
DifferentMountingAngle
Flushing Mounting Silo Application

11
4.7Systemwiring
Nonehazardarea Hazardarea
Extube Extube
Relayoutput Power supply
Extube
Power supply
lineinlet Relay
output
line
out
Figure4.4Systemwiring
4.8SensingElementwiring
Assurepowertothe equipmenthasbeen turned offbefore
opening the explosion-proofhousing. Alsomakesurerelay power
hasbeen turned offmore than tenminutes
Forintegralmounting,thesensing elementisusuallypre-wiredatthefactory.Ifthesystemwereshippedunassembledor
you wanttoreplace thecableseefigure4.5below.Allofthesensingelementconnectionsaremadetotheterminalsonthe
oppositesideofthepowerand relayconnections.Theshieldwire(red)and thecenterwire(blue)aretwisted,besuretheshield
wireconnectstotheelectronicunit shieldterminal(DSH),thecenterwireconnectstothecenterterminal(CW).Since ametal
housingisusedtheelectronicunitgrounddoes nothavetobeconnected. At theprobeend, connecttheCenterwire(blue)tothe
centerrod ofprobeand theshieldwire(red)totheshieldofprobe.See figure4.6systemwiring.Remotewiringconnections
arethesameas integralexceptthegroundwireisconnectedatboththeprobeandelectronicunits.
Figure4.5IntegralSystemwiring

12
Figure4.6RemoteSystemwiring
4.9Relaywiring
Assurepowertotheequipmenthasbeenturnedoff beforeopening
the
explosion-proofhousing.Alsomakesurerelaypowerhasbeenturnedoff
overtenminutes Besureall powerand relaywires doNOThavepower!
Thesection area ofwires shouldbetween0.13-2.1mm2(AWG14-26),insulationratingover1500V.
Use approvedsealedfittingintheconduitentrances oftheexplosion-proofhousinginhazardousareas.
Therelayisadouble-pole,double-throw(DPDT)drycontactrelay.Therelayservesas aswitchand does notprovidethe
powertooperateanannunciatororotherequipment.All relayconnectionsaremadetotherighthandterminalstripsonthe
powersideofelectronicunit.See figure4.7as relaycontacts.
TerminalConnectionProcedure
1、Openupperlidofthehousing.
2、Feedtherelaycontactwires throughtherighthandentrance fittingintohousing.
3、Adjust thecableforsuitablelength,
4、Connectthewires totheproperterminalsand verifyit iscorrect.
5、Tightentheupperlidagain.
Instrumentuses normalrelaylogic;therelayfailssafeand contactsarede-energizedinalarm.Thisisalsotheno power
state.
AredLEDindicates thattherelayisde-energized(reset),normallythisisthealarmcondition.AyellowLEDindicates
thattherelayisde-energized(reset) andthereisanelectronicunit failure.AgreenLEDindicates theunitisinthe “normal
position”andtherelaycoil energized.
HighlevelFail Safe(alarm)meansthattherelaywill de-energize whenlevelishigh.These contactsalsode-energize
indicatinghighleveluponloss ofpower.
Low-levelAlarmFail Safe(alarm)meansthattherelaywill de-energize whenlevelislow.These contactsalsode-energize
indicatinglowleveluponloss ofpower.
See figure4.8relaycontactsinnormalcondition.
Remark:Thereisnoabsolutefail-safedevice made. Criticalapplicationsshouldhaveredundantorback-up devices.

13
4.7relaycontacts4.8contactposition innormalstatus
4.10Powerwiring
Assurepowertotheequipmenthasbeenturnedoff before opening
the
explosion-proofhousing.Alsomakesurerelaypowerhasbeenturnedoff
overtenminutes!!
Thecross section area ofwires shouldbebetween0.13-2.1mm2(AWG14-26),insulationratingover1500V.
Use approvedsealedfittingforanyconnectionstotheexplosion-proofhousinginhazardarea.
All powerconnectionsaremadetotheterminalstripontheleftsideofelectronicunit. See figure4.9powerwiring.
1. Openupperlidofthehousing,
2. Feedthepowerwiresthrough thelefthand entrance fittingintohousing.
3. Adjust thecableforsuitablelength,
4. Connectthewires totheproperterminalson theleftsideoftheunit and verifyit iscorrect.
5. Tighten the upperlid again.
Figure4.9powerwiring
SECTION5FUNCTIONSETTING
5.1Process materialsetting
See figure4.9powerwiring,the “SETPOINT “istheoperatingcontrolusedtocontroltheswitchpointat
whichtherelaychanges state.Turningtheswitchpointadjustmentclockwise increases theamountofsensed
capacitancerequired(lesssensitive)tochangetherelaystate.Counterclockwisereduces theamountofsensed
capacitancerequired(moresensitive)tochangetherelaystate.AGreenLEDindicatesthattheelectronicunit is
inthenormalstateand therelayisenergized.ARedLEDindicates thattheelectronicunit isinalarmand the
relayisde-energized.
5.2HLFS/LLFS setting
TheHighLevelFail Safe(HLFS)/LowLevelFail Safe(LLFS)jumperdetermines whethertherelaywill de-energize
whenmaterialishigherorlowerthanthesetpoint.HLFS meanstherelaywill de-energize (alarm)whensensedcapacitance
(level) ishigherthanthesetpoint.LLFS meansrelaywill de-energize (alarm)whensensedcapacitance (level) lowerthanthe
setpoint.Theinstrumentissuppliedinthefailsafemoderequestedwhentheorderisplaced(HLFS, ifnotspecified.)The
HLFS/LLFS jumperislocatedon thesideoftheunit.See figure5.1ElectronicUnitSketch

14
HighalarmLowalarm
Figure5.1HLFS/LLFS
5.3Timedelaysetting
Thetime delayadjustmentisapotentiometerlocatedon thetop oftheunit “TIME DELAY”.It couldadjust
theresettimeoftherelaywhenanalarmconditionceases toexist. Clockwise theadjustmentcouldincreasing
thetimedelay.
Iftheunit without “TIMADELAY”adjustment, thenno time delayoption available.
5.4Rangesetting
Rangesetting normallybe adjustatspan 2(i.e. the second place isat “ON”,following issame),factory
setting alwaysalso atthatposition.
Rangesetting aton the top ofthe unit --”RANGE”, change the switch No.2、3、4position,could measure
differentprocess materialthrough differentsensing elementIL.While one position at “ON”, the othertwos
should at “off”position.
Relationship between materialconductivityand span position:
Span 2:Sensing elementlengthless than 300mm orhigh insulating materialsuch as:plastic
powder/granularorfoam;
Span 3:Sensing elementlength less than 3000mm orgeneralinsulating/conductive material;
Span 4:Sensing elementlength over3000mm orsemi-conductive/conductivematerial.

15
SECTION6CALIBRATION
Assurepowertothe equipmenthasbeen turnedoffbeforeopening the
explosion-proofhousing. Alsomakesurerelay powerhasbeenturnedoffover
ten minutesand controlelements are in manual.
6.1StartUp
TheAVI-PDU isreadyforoperation whenthesystemisinstalledand wiredinaccordance withprevious
instructions.Theareashouldbeevaluated,and iffound safe,thehousingcovershouldberemovedforstart-up.It
isadvisableat thistime todisablecontrol elementsuntil properoperation isverified.
6.2FactoryCalibration
All AVI-PDU seriesproductsarefactoryconfiguredtoswitchon waterbasedconductingmaterials(setpoint
adjustment isset tofull clockwise position)and sealedwithapaperseal.
Nocalibrationisrequiredforconductivematerialapplications.
Ifthecalibration sealisbrokenorverification ofthetrippointisrequiredturntheadjustmentscrewfull clockwise for
conductiveapplications.Forinsulatingmaterialapplications, see section 6.3, forconductingmaterial,see section 6.4
6.3CalibrationforInsulatingMaterials(HLFS)Horizontalmount.
A. Be surethematerial level iswell belowthesensingelement.
B. Turnthesetpointadjustmenttothefull counterclockwise(CCW)position.Theredalarmlightwill
light.
C. Turnsetpointadjustmentslowlyclockwise (CW)until therelayjustchangesstate.(LEDchangescolor
toGREEN).Makeapencilmarkon thelabelatoneofthescrewdriverslotends.See figure
6.1Calibration inInsulatingMaterial 1
D. Increase thematerialleveluntil it iswell abovethesensingelement. (REDLEDturnson).See figure
6.2Calibration inInsulatingMaterial 2.
E. Turnthesetpointadjustmentslowlyclockwise(CW)untilrelayonce againjustoperates(LEDchange
toGREEN)countingthenumberofrevolutionsrequiredtochangestates,oryou come totheend ofthe
adjustment travel.
F. Turntheadjustment backcounterclockwise(CCW)halfofthenumberofturnsthatwascounted.
G. Recordnumberofturnsand saveforfuturecalibration reference. Calibration isnowcomplete..
GreenLEDLit
material
interface
RedLED Lit
interface
material
6.1Calibration inInsulatingmaterial 16.2Calibration inInsulatingmaterial 2
Caution! Ifthesetpointstatuschangeless thanoneturnortherelaydoes notchangestate, consult factory.
6.4CalibrationforConductingMaterials(HLFS)
A. Be surethematerial level iswell belowthesensingelement
B. Turntheset point adjustment tothefull counterclockwise(CCW)position.TheLEDwillbered.
C. Turnsetpointadjustmentslowlyclockwise (CW)until therelayjustchangesstate.(LEDchangescolor
toGREEN).
D. Turntheset point adjustment slowly
•1/4~1/2turnsfordielectricconstant (K)less than2.
•1/2~1 turnsfordielectricconstant (K)between2~ 10
•1~2 turnsfordielectricconstant (K)between10~80.
•2~5 turnsforconductivities<0.5 micromhos(μS/cm)
•Full clockwiseforconductivities over100 micromhos(μS/cm).
6.5Pre-calibrationoremptycalibrationforSTART-UP(HLFS)
A. Insurevesselisemptyormaterialiswell belowprobe.
B.Turntheset point adjustment tothefull counterclockwise (CCW)toposition (LEDwill bered).
C.Turnthesetpointadjustmentslowlyclockwise (CW)until therelayjustchangesstate(LEDchanges
colortoGREEN).
D. Turntheset point adjustment slowlyclockwise (CW)3/4turn, thisiscalledas pre-load, ifthematerial is
highinsulatingone,thenmakeit as 1/2turnas agood initialsetup.Normally3/4turnisforgeneral

16
insulating/conductivematerial, forhighconductiveone, thanmakemoreturns.
SECTION7TROUBLESHOOTING
7.1Introduction
AVI-PDU series isasolid-statedevicewithno movingpartsexceptthealarmrelay.Neithertheprobenor
theelectronics requireroutinemaintenanceorperiodicadjustments.Allcomponentsaretestedand inspected
duringmanufactureand thenas acompletesystem.Thesystemsaredesignedtogiveyearsofunattendedservice.
Aspareelectronicchassisisrecommendedforevery25 unitssothat, incase ofafailedunit, acritical
application will notbedelayedwhiletheunit isreturnedtothereporfactoryforrepair orreplacement. A
completesystemisrecommendedforcriticalapplicationsorforprojectstart-up whereadditionalapplications
mayberequired.
NoSPECIALtoolsarerequiredforservicingtheAVI-PDU productlineexceptadigitaloranalog
multi-meterformeasuringtheresistance oftheprobeand cableand checkingtherelaycontacts.
Use thefollowingtroubleshooting procedures tocheckouttheAVI-PDU levelcontrol.Ifattemptstolocatethedifficulty
fail, notifyyourlocalFITECHNIC®representativeorcall thefactorydirectly.
Assurepowertotheequipmenthasbeenturnedbeforeopening
the
explosion-proofhousing.Alsomakesure powertotherelaycontactshave
beenturnedoff overtenminutesandcontroldevices areinmanual.
7.2Testingtheelectronicunit
Duringelectronicunit testing, careshouldbetakenaslinepowerwill beonthepowerterminals. Also
assurerelaypowerisoff!
A. Disconnect thesensingelementwires fromtheinstrument byremovingthebluewirefromthecenterterminal
and theredwirefromshieldterminal. Leavethepowerconnected.See figure7.1.
B. Connect a1to10pFcapacitorbetweencenterwireand ground.
C.Startingwiththesetpointadjustmentintheextremecounterclockwise(CCW)position,turnthescrewdriver
clockwise (CW)until therelayjust operates.
D.Rotatethesetpointadjustmentbackand forthaboutthispoint, observingthetravelofthescrewdriver
betweentherelaypull-inand relaydrop-out. Iftheinstrumentisworkingproperly,thescrewdrivershould
travel lessthan1/4turntooperatetherelay.
Ifinstrumentdoesn twokproperly, consult service department.
7.1Testingelectronicunit

17
7.3Testingthesensingelement
A. See figure7.1.Disconnectthesensingelementwires fromtheinstrumentbyremovingthebluewire
fromthecenterterminal and theredwirefromshieldterminal.
B. See figure7.2. Usingananalogohmmeter,measuringthefollowingvalues
•Centerwiretoground ohms
•Centerwiretoshield ＿＿＿＿＿＿＿＿ohms
•Shieldtoground ＿＿＿＿＿＿＿＿ohms
Usingthesame analogohmmeteron theDC voltagescale,measurefollowingvalues:
oCenterwiretoground ＿＿＿＿＿＿＿milli-volts
oCenterwiretoshield ＿＿＿＿＿＿＿ milli-volts
oShieldtoground ＿＿＿＿＿＿＿＿ milli-volts
C. Resistance result initemBshouldoverfollowingvalues:
•Centerwiretoground ohms
•Centerwiretoshield500ohms
•Shieldtoground 150ohms
Voltageresult initemBshouldless thanfollowingvalue:
oCenterwiretoground mV
oCenterWiretoshield100mV
oShieldtoground 200mV
D.Ifvoltageresultsareoverabovevalues orresistanceresultsarelowerthanabovevalues,
please cleanthesensingelement and do procedureBagain.
AneworcleanSensingelement without build-upwill havethefollowingvalues:
üResistance:higherthan1M atall testpoints,consult factory
üVoltage:lowerthan200mVatall test points, consult factory.
DSH
CW
GND
multimeter
7.2Testingsensingelement
7.4Testingtherelaycircuits
Becarefulduringrelaychecksince linepowerispresentonpowerterminals.
A.Therelaycircuitsconsistofdouble-poledouble-throwrelaycontactbroughtoutto
terminalstrips.
B.Adjust equipment persection 5.1.
D. Relayoperation maygenerallybeheardas aaudibleclickwhenthebackground noise isnottoohigh.To
besurethatthecontactsactuallychangestate,disconnectthewirestotherelaycontacts,use an
ohmmetertocheckifrelaycontactsworkproperly.Inmanycases,contactscanoxidizeand notcarry
current.
7.5Testingthecoaxialcable
Disconnectall three spadelugsofthecoaxialcableattheelectronicunit andsensingelement. Usinganohmmetermeasure
followingvalue, checkiftheresult meetsthevalueinbrackets.
See figure7.3integralcable, figure7.4remotecable.
Integral cable:
Resistance betweenthetwobluespadelugs（<2 ）
Resistance betweenthetworedspadelugs（<2 ）
Resistance betweenthered&bluespadelug（>100M ）

18
blue blue
red
red
green
blue
red
blue
green
red
7.3Integralcable7.4Remotecable
RemoteCable
Resistance betweenthetwobluespadelugs（<10 ）
Resistance betweenthetworedspadelugs（<10 ）
Resistance betweenthetwogreenspadelugs（<10 ）
Resistance betweenthethree different colorlugs（>100M ）
7.6PossibleProblemandCause
Problem PossibleCause Solution
1.Instrument indicates
alarmat all time a. Severecoatingbuild-up (HLFS) a. NeedSuperShieldBarrierPotential technology Consult factory.
b. SensingElement alwaystouch
material (HLFS) b. Needshorterinsertion length. Consult factory.
c. Defect insensingelement. c. See section 7.3.
d. Improperwiringd. See section 4.6,4.7.
e. Impropercalibration. e. See section 6.3,6.4.
f. Electronicunit malfunction
(YellowLED) f. Replaceunit
g. LEDfailedg. Replace fuseofunit orturnpoweron again
2.Instrument never
indicates alarma. Sensingelement not “seeing” material (HLFS) a. Needlongerinsertion length. Consult factory.
b. Brokenwiringb. Replace signalcable
c. Impropercalibration c. See section 6.3,6.4
3.Instrument can t be
calibrateda. Improperwiring a. See section 4.6,4.7
b. SensingElement not “seeing”
material (HLFS) b. Needlongerinsertion length. Consult factory.
c. Highinsulatingmaterial c. Needhighdiscrimination unit. Consult factory.
4.Instrument gives a
false alarm a. ImproperCalibration. a. See section 6.3,6.4.
b. Loose wiring b. See section 4.6,4.7,4.8.
c. Electronicunit malfunction. c. See section 7.2.
5.Instrument
operates intermittently.
a. Impropercalibration. a. See section 6.3,6.4
b. Loose wiring. b. See section 4.6,4.7,4.8.
c. Highinsulatingmaterial. c. Needhighdiscrimination unit.Consult factory.