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FOREWORD
outlinesthe
o*iuiriGi.na pro""or.rr""torh.nloqraphi" infraredinspections'lt isoneoftheGuidelines
i"oL-"""""0 "ip*ds uponthe'1988-document,
GuidelinesforSoecifvinoandPerformino
redlnsoections.
rrGuidelinesavailablefromthe InfraspectionInstituteare:
Aoplicalion
)
)
TemoeratureMeasurement
;e GuidelinesreDresenttheworkof manypracticing,infraredthermographersand other
)rls. We acknoiledgethemfortheirvaluablecontnbulrons'
PaulGrover.Director
InfraspectionInstitute
January,1993
Transmittance
Cameras
L-3
3. )
GUIDELINEFORINFRAREDINSPECTION
OF ELECTRICALAND MECHANICALSYSTEMS
TABLE OFCONTENTS
PART1:GENERAL ...........................Page2
PAFIT2: TEMPERATURECFtITERIAFORELECTRICALSYSTEMS....."."Page7
I- eART3'TEMeERATUREcRtrERlAFoRMEoHANIoALSYSTEMS........Page11
pART4:REFERENCES....................... ..........................Page15
FirslEdition,CoPyrighl1993
lnlrasDectionInstitute.Inc.
.1971ShelbumeRoad,SuiteC
Shelbume,VT 05482-7174USA
PH: 802-985-2500FAX: 802-985-2726
Thisdocumentmavbe reproducedfor personaluseandnotlor prolil,withoutcharge,
providedyou includeallof thecopyrighlandaddressintormationlistedabove. Failureto
includettiisinlormationwithanyreproductionis aninfringementof thecopyrightandsubject
to legalactionandconsequences.
InnoeventshallInfraspectionInstitutebe liableto anyonefor sp€cial'collateral,
t Incidentalor consequehtialdamagesin conjunctionwithor arisinglromuseof this
Guideline.
) , 4
4. ) PART1: GENERAL
1.0GuidelinePurposes
The purposesof thisGuidelinearelo:
1.1 providea commondocumenlfor theenduserto specifyinfraredinspectionsandthe
infraredthermographerto performthem.
1.2 listlhejointresponsibilitiesof theenduserandtheinfraredfhermographerthat,when
caniedout, willresultin thesafestandhighest.qualityinspectionfor both.
1.3 outlinelhespecificcontentfor documentingqualitativeandquantitativeinftared
Inspecltons.
1.4 providecriteriafor evaluatingtheseverityof an exception.
2.0Definitions
Forthe purposeof thiSGuideline,
2.1 a guidelineisa sel of speciticationswhichdetinethe purposes,scopeandconlentota
proceoure.
E 2.2 qualitativeinfraredthermographyisthepracticeof gatheringinformationabouta
stlucture,system,objeclor processbyobservingimagesof infraredradiation,and
recordingandpresentinglhatinformation.
2.3 quantitativeinfraredthermographyisthepracticeof measutingtemperaturesof the
observedoatlemsof intraredradiation.
2.4 theend user is thepersonrequestingan infEredthermographicinspection.
2.5 an infrared inspectionislhe useof inharedimagingeguipmentto providespecific
lhermalinformationandrelaleddocumeniationabouta sfucture, system,objector
Drocess,
2.6 an intraredthermographerisa personwhoperformsanddocumentsan infrared
inspection.
2-7 a qualified assistantis a personprovidedandaulhorizedby the enduserto perform
lhe tasksrequiredbylhe infraredlhermographer.Hey'sheis knowledgeableof the
opeEtionandhistoryof theequipmentto beinspectedand is trainedinallthesafety
practicesandrulesof lhe end user-
2.8 an exception isan abnormallywarmorcool@nnector,conducloror componentthat
maybea potentialproblemforlhe enduser.
D
5. I3.0Scope of the Guideline
4.OResponsibilitiesof the lnfraredThermographer
Thepurposeofaninfraredinspeclionistoidentiryanddocumentexceptionsintheend
useiseleclricaland/ormectranicalsystems.
3.1.1 Ineleclricalsystems,exceptionsareusuallycausedbylooseordeteriorated
connec{ions,shortcirclits,overloads,loadimbalancesorfaulty,mismatched
orimproperly-installedcomponents.
3.1.2 Inmechanicalsystems,exceptionsareusuallycausedbyfrictiondueto improper
lubrication,misalignment,womcomponentsormechanicalloadinganomalies.
Exceptionsininsulationsystemsareusuallycausedbymissingordeteriorated
malerials,improperinstallationorinsumcientamountsofmaterial.
Providingopinionsaboutthecausesofthesepattems,theintegrityofthesystemor
recommendationsforcorrecliveaclionsrequireknowledgeandskillsbeyondthoseof
infraredthermography.
3.2.1 lnfraredthermographywill bepresentedasaninspediontechniquetogalher
andpresenlinformationaboutthesystemata specifictime.
3.2.2Infraredthermographywill notbepromotedasa rcmedialmeasure.
3.2.3Aninfaredinsoec{ionofelec{ricalandmechanicalsvstemsdoesnot assure
properoperatibnofsuctrequipment.Othertestsanapropermainlenanceare
necessarylo assuretheirreliableperformance.
ThisGuidelinesupports-lheproceduresandspecificationsstatedinNETAlvtTs-19891
andMIL-STB-2194(SH)'. However,compliancewiththisGuidelineisindependentof
compliancewilhanyotherstandard.
3.1
3.2
4.1
4.2
4.3
4_4
Infraredinspec{ionswill be performedwhenenvironmentalandphysicalconditionssuch
as solar gain,wind, surfaceandatmosphericmoistureand heattransferare favorableto
gatheringaccuraiedata.
The infraredthermographerwillhavesufficientknowledgeof thecomponents,
conslruclionandtheoryof electricaland/ormechanicalsyslemsto understandthe
observedoattemsof radiation
The infraredlhermg=grapherwill usethermalimagingand/ormeasurementequipment
withc€pabilitiessufficientto meetthe inspec{ionrequirements.
The infraredthermographerwill beaccompaniedby a qualifiedassistantwho is
knowledgeableof theequipmentbeinginspeded.
Unlesshe/sheis a licensedelectrician,professionalengineer,or hasotherequivalent
qualifications,the inlraredthermographerwill not perfoimanytasksthatarenbrma y
donebylhese personnel.Unlessso qualifiedandauthorizedbytheenduser,the
Inrareotnermograpner
4.5
L-6
6. 4.5.1 will nol removeor replacecoversoropenorclosecabinetscontainjngelectricalor
mechanicaleouioment.
4.5.2 will nol measureeleclricloadsof theeouiDment_
4.5.3 will.nol touchanyinspectedequipmentandwillmaintaina safedistancefrom
sucnequrpmenr.
4.5.4 will complywiththesatetypracticesandrulesot the enduser.
4.6 Whenperformingquantitativeinlraredinspections,the infraredthermographerwill
assurethatalltemperature-measuringequipmentmeetsthe manufacttrers'standard
specificationstor accuracy.
4.7 Alletrepai, andwhenrequestedby theenduser,eachexceptionshouldbe re-insDected
lo assurethatitsoperatingtemperatureis normalandthe potentialproblemcorrecied.
5.0 Responsibilities'otthe EndUset
5.1Theendusdrwillprovideor_helpdevelopaninventorylistoftheequipmenttobe
inspectedina logicalandefficientroutethroughthetacility.
5.2Theenduser_willprovidea qualifiedassistant(s)whoisknowtedgeableottheoperation
andhistoryoftheequipmenttobeinspected.Thisperson(s)wilfaccompanytheinfrared
thermographerduringtheinspectionand,unlessspeci{iedotherwise,wiitbeaualiliedand
authorizedbytheenduserto:
5.2.1 obtainauthorizatjonsnecessarytogainaccesstotheequipmenttobeinspected
andwillnotityoperationspersonneloftheinspectionactivities.
5.2.2 openand/orremoveallnecessarycoversofcabinetsandenclosurescontainino
theequipmenttobeinspected.
5.2.3 closeand/orreplacethesecabinetandenclosurecoversimmediatelyalter
inspectionbytheinlraredthermographer.
5.2.4assurethattheequipmenttobeinspectedisunderadequateload,create
satisfactoryloadswhennecessary,andallowsufficienttimetorrecenly-energzed
equipmenttoproducestablethermalpatterns.
5.2.5 measureelectricloadswhenrequestedbytheinfraredthermographer.
5.3 Theendusertakesfullresponsibilitytorconsequencesresuttinglromactionstaken,or
nottaken,as_aresultol inlormationprovidedbyanintraredinspection.
5.4 Alterrepair,eachexception.shouldbere-inspectedtoassurethatitsoperating
femperatureisnormalandthepotentialproblemcorrected.
L-7
7. 6.0 Documentation
6.1 Thelhermographerwillprovidedocumentalionfor all infraredinspections. The
followinginformationwillbeincludedina writtenreporlto theendusen
0.1.1 thenameandanyvalidcertificationlevel(s)andnumber(s)of the inhared
thermographer.
6.1.2 the nameandaddressof theenduser.
6.1.3 the name(s)of theassistanl(s)accompanyingtheinfraredthermographerduring
theinspection.
6.1.4 the manufaclurer:modelandserialnumberof lhe infraredequipmentused.
6.1.5 a listof allthe equipmentinspectedandnotationsof theequipmentnot
inspectedonlhe inventorylisl
6.|.6 thedate(s)of the inspectionandrvhenlhe reportwasprepared.
6.2 rvhenperforminga qualitativeinfraredinspeclion,theinfraredthermographetwill
providethe followinginformationfor each exceptionidentified:
6.2.1 the e)€c1locationof theexception.
6.2.2 a descriptionof lhe exceptionsuchas itssllnificanlnameplatedata,phaseor
circuitnumber,raledvoltrage,amperageralingand/orrotalionspeed.
6.2.3 lvhensignificanl,theenvironmentalconditionssunoundingtheexception
includingtheair temperature,windspeedanddireclion,andthe skyconditions.
6.2.4 hardcopiesof a thermalimage(thermogram)andconespondingvisible'lightimage
of the exceplion.
6.2.5 thefield-of-viewof the infraredcameralens.
6.2.6notationofany windows,filtersor externaloplicsused.
6.2.7 if desired,a subjecliveevaluationratingprovidedby thequalifiedassistantand/or
end userrepresentative, of the importanceof the exceptionto the safeand
continuousoperationof the system.
6.2.8 anyotherinformalionor specialconditionslvhichmayaffecttheresults,
repeatabilityor interpretiationof the exception-
I
I
a
L 8
8. 6.3 Whenperforming.aquantitative.infrared_inspection,theinfraredthermographerwillprovidethefollowingadditionalinformation:
6-3.1 thedistancefromtheinfraredcamerato theexception.
6-3-2 whenev€rpossible,themaximumratedloadof theexceptionanditsmeasured
loadal thetimeottheinspeclionand
6.3.3 thepercentageroadonrheexception,carcuratedby dividingitsmeasuredtoadbytheratedload-
6-3.4 theemissivlty,_reflecledtemperatureandrransmissionvaruesusedto carcuralerhelempeEtureof lhe exception._
6.3.5 whengsingdelta,T-temperature.criteria,thesurfacetemperatureo, theexceptionandof a definedreferenceandtheirtemperatureOmeiericJoi
6.3.6 whenusingabsorutetemperalurecriteria,thesurfacelempe'ture otthe exceprionandthestandardandlhestandardtempdrature(s)releren'ced-
6.3.7 if desired,an evaluationof thelemperatureieverityof the exceptton.
6.3.8 if^de^sjre4
-a^r-"1?ir_plgllyFlirqforlhe exceptionbasedon itssubjecliverating,
remperatureseventyratlngoranave|:tgeof both.
, _ J
t.rl
L 9
9. 7.O
PART2: TEMPERATURECRITERIAFORELECTRICALSYSTEMS
Delta-TCriteria
7.1 The infi'aredthermographermayusethefollowingdett+T (temperatured,[.rqlcg)'
critlti. to uvaiuateifie iemperati.rreseverityof anlxception. ThesedeltaT criteriaare
reoorledas thetemDeraturbriseof theexc-eptionabovethetemperatureof a defined
reierence,whichis iypicallytheambientairtemperature,a similarcomponentunderlhe
samecondilionsor lhe maiimumallowabletemperatureof thecomponent
N.E.T.AMaintenanceTestinoSoecificationsl,for eleclricalequipment
1) 1to 3C":possibledeficiencyandwaranls invesligalion.
2) 4 to 15C":indicatesdeficienc]4repairas timepermits.
3) 16C"andabove:indicatesmajordeficienq4repairimmediately.
MilitarvStandard',for elec{ricalequipment
1) 10io 25C':comoonentfailureunlikelybutcorreciivemeasurerequiredat next'
scfieduledrotdinemaintenanceDeriodor as schedulingpermits.
2) 25to 40C':componentfailureprobableunlessconected.
3) 40to 70C':comoonentfailurealmostcertainunlesscotrected.
4i ToCfandaboveicomponentfailureimminentstop survey. Informcognizant
officers.
Experience-Based.3for elec{ricaland/ormechanicalequipment
Anydelta-Tclassificationsystembasedon experience,suchas thefollowing3:
1) Oto 1oC':conectivemeasuresshouldbetakenat the nextmaintenanceperiod.
2i 10to 2OC1conedive measuresrequiredas schedulingpermits.
3) 20to 40C':coneclivemeasuresrequiredASAP.
4) 40Clandabove:conectivemeasuresrequiredimmediately.
MotorCoresr(ontestbencfi,notinservice):
1) o to loco:noexceptionlikely.
2) |0 to 20C':possibleexception,consultmotorcoretestdata.
3) 2oC9andabove:exceptionlikely.
Absolute TemperatureCriteria
8.1 The infraredthermographermayuseabsolutetemperaturecriteriabasedon thefollowing
ANSI,IEEEandNEMAor otherstandardsto idenlifyelectricalsystemexceptions.
8.2 All temperaturesof thefollowingslandardsarespecifiedin Celsiusas follows:
8.0
AmbienVRatedRise/MaximumAllowable
L , l 0
10. 8.3
a-4
Whentheexceptionis healingseveraladjacenlcomponenls,lhe lowesttemperature
componentspecificationshouldbe used.
Example:Youareinspeclinga heatinglerminalthatconnectsan insulated
conductorto a circuitbreaker.The componentwiththe lowesttemDeralure
specificationshouldbeused
Whensevelalditferenltemperaturesfor similarequipmentaregiveninthe referenced
srirndards,tnetowesttem.peratures(mostconseryative)arelisted, lf an exception
temperatureexceedsthelisledmaximumallowableabsolutetemperaturelimit;it could
b^eoperatjnga.ta temp€ralurelover thana higher(lessconservative)specificaiion.
uonsutlInerelerenceosEndard(s).
t
8.5Whenlheinfraredthermographeris unableto determinetheclassof insulationor
equipmentbeingins_pected,hey'sheshouldusethelowest temperature(most
mnservative)specificationwilhinlhecomponentgrouping.
Example:Youareinspectingan insutatedwirethalhasnovisiblemarkinos.
Usethelowestlemperaturespecificationforany conductorinsulation.
-
8.6 Unlessnoted.otheMise,lhese-absolutelemperaturecrileriaare basedonequipment
operatingat theqtatedambienttemperatureandat .lOO%of theirratedload, fhe
followingformula'canbeappliedto theseabsolutetemoeraturecriteriato oivea
conectedmaximumallo,Ebletemperature(l"Max""")foi thereducedoperjtingloadand
actualambienttemperatureof theexceDtion:
Tmax* : (T,hdd"J(4JA.,.)' " + Tamb*
Tmax* = conecledmaximumallowabletemperature
T.bd,8.= raledtemperalurerise(fromstandard)
A,* = measuredload,inamperes
A,"l"d= ratedload,in amperes
Tamb@ = measuredambienttemperature
8.7 AbsoluteTempeEtureCriteria:
Conductors(lowesttemperaturecriteria):
Bareconduclors6,.infteeair----.......--..,
Eareoonouclors,tnendosure........--- -.------.....4U3On0
BareconducloE,enclosuresurface.. .....-.---...4Ot2Ot6O
InsulatedconductorsT,infreeair-.--....- .---------.30/30/60
Insulatedconductors,inenclosure-.--.. ...........30/30/60
lnsufatedconductors,enclosuresurface.........,...,......--................-3Ol2Ol5O
Insulatedconductors,insun.--..........--. ..........-50/10160
L-l1
11. ConductorInsulationst:
T,TWR,RWRU..... ...........30/30/60
THWPofyethylene,XHHqRH-RW..... ..............30t45ft5
VamishedCambric. ............3U47m
PaperLead............ ............-30/50/80
VamishedPolyester.......-.----..---........... .-.-.-.....30/55/85
THH,CrossLinkedPolyethylene,
EthylenePropylene ---.---....30/60/90
SiliconeRubber..... ..---..--...301951125
ConnectorsandTermin?lions(lowesttemperaturecriteria):
Metafslo,silverorsilveralloy-............... ...........4O14O1aO
Metals,copper,copperalloyora1uminum.....................................40/50/90
Metals,afuminuma11oy......................... ..-...-...521531105
OvercunentDevicess(lowesttemperaturecriteria):
Ciranitbreakers.moldedcase.......,.. ................40120160
Cirqritbreakers,allothers.....,.......,..... .............408OnO
Fuses..................... -.........--4U30ftO
andSuoportsro(lowestlemperaturecriteria)...,..............................4OgonO
Bushinosrl(lowestlemperaturecriteria):
Transformer,lowerend............... .....................40/55/95
Cirojit breaker,lowerend..........,.... .................40/40/80
Exlemafterminal... .............40130170
CoilsandRelavssrl
Class90................ .............40/50/90
class105.............. .............40/65/i05
Class130.............. .............40/90/130
Class155.............. -.-.-........4on115s
Class|80.....-........ ............4Ot't4OnAO
cfass220.............. .............4onaot22o
AC Motors.FieldWndinosr3:
1.0OSF,classA... .....-.......40/60/iOO'f.00SF,cfass8.... .............4Ot8Ot12O
1.00SF,classF..... ............4t.t15t145
1.00SF,cfassH.... ............4)t125t165
1.15SF,class8.... -.----.......40/90/.130
1.15SF,cfassF.... -------......40t'l1st1ss
Note:Casingtemperaturesmaybe lowerlhanthesespecifiedwindingstemperatures.
L - i 2
12. DCMotorsandGenerators.Windings'3:
1.00SF,classA..... ............40nU110
1.00SF,cfass8..... ............4011001140
1.OOSF,classF..... ......---..40/130/170
1-oOSF.ctassH.... ...........-.401155/195
1-25SF (2hr),class8................... -......--.--.......4O14O42O
1.25SF (2hr),classF.......-........... ...................40/1'10/'150
Note:Casingtemperaturesmaybe lowerthanthesespecitiedwindingstemperatures.
CylindricalRotorSynchronousGenerators.Air Cooled.Casino'3:
ClassB.................. -----........4OnOn1O
ClassF.............-.-.- -...........40/90/130
ClassH-................. -.--.......4O1'l'lOl15O
Transformers,DistribulionandPowerr'r5r5:
Drytype,class105,windings......... .................30/55/85
DrVtirbe.class150.windinqs.....-... .................30/80/110
Drlti,be.ctass'l85.windinas......... .................30/115/145
Drl tlbe, class220,windin9s............... ...........30/150/180
Oilcooled,55C"rise,casin9................ ............30/55/85
Oilcooled,65Corise,casing.... .......................30/65/95
Notes: 1.OiFcooledcasingtemperaturesmeasuredneartopof liquidinmain tank
2. Most55C"risetransformerbuiltbefore1962.
3. Forspecialtytransformers(otherthanpoweranddistribution)or other
liqui&cooledequipment,as speciliedonlhe nameplate.
8.8 A detla.Tcriteriasystemmaybeusedin conjunctionwiththeseabsolutetemp€ratute
criteriato ratethet'emperatuieseverityof an exceplionabovethemaximumallowable
tempeEture.Usethedelta-Tcrilerialistedin section7.1.
L- l3
13. PART3: TEMPERATURECR|TER|AFORMECHANTCALSYSTEMS
9.0 Delta-TCriteria
9-1 The infraredthermographermay use detta-T(lemperaturedifference)cdteriato rate the
temperatureseverityof mecfranicalsystemexceptions.These delta-Tsiteria are
usually-reportedasthe temperalureriseof theexceptionabovethetempeialureof a
definedreference.Uselhe della-Tc.iterialistedin sec{ion7.1.
9.2 Bytakingmultiplemeasurementsovertimeof similarcomponentsundersimilar
operatingandenvironmentalcondilions.statisticalanalysiscanbe usedlo set
operationallimitsfor trendingand predictingthetemperatu'reperformanceof these
components.
10.0 AbsoluteTemperatureCriteria
10.1 Theinfraredihermographermayuseabsolutemaimum allowabletemperaturecriteria
basedon publishedstandardsto identrymechanicalsystemexceptioni.
10.2 Whenan exceptionis heatingseveraladjacentsystemcomponents,thecomponent
havingthelowestlemperaturespecificationshouldbereferenced.
E)€mple:Youare inspectinga bearingof a motor. Theapplicableadiacent
systemcomponentsare thesealsandthelubricant Thecomponent(bearing,
sealsor lubricant)havinglhe lowesllemperaturespecificalion'shouldbe
referenced.
Note:In mostcases,lhe lubricantwillhavethelowesttemperaturespecification.
10.3 Whenunableto determinethe typeof bearing,lubricanlor seal,theinft.ared
thermographershouldusethe lowestcomponenttemperaturespecificationwithinthe
applicablegroup.
E)€mple:.Youareinspectinga bearing.you identifythebearingand lubricant
typesandtemperalurelimits,butyoudonotknowthetypeof seal. Fromthe
list,selec{the lowestapplicabletemperaturespecificati6irfor anyseal.
Compareyourmeasuredbearingteinperature-tothe lowestof ttiethree
componenltemperatures(thebearing,lubricantandseal).
'|0.4 The infraredthermographeroftencannotdirec{lymeasurethesurfac€sof lhe
crmponentsin lhesespecificationlists. Careandqoodiudomentmustbe usedwhen
applyingthesespecificationsto actualfieldtemperatureheEsurements.
10.5 Unless.noted,temperaturespecificationsarebasedonequipmentoperatingat 1Oo%of
theirratedload/speed.All temoeraturesareinCelsius-
L 1 .
