Biological Insulating Liquids: New Insulating Liquids for High Voltage Engineering

329 Pages·2023·10.633 MB·English

by  Ernst Peter Pagger, Norasage Pattanadech, Frank Uhlig, Michael Muhr

Ernst Peter Pagger
Norasage Pattanadech
Frank Uhlig
Michael Muhr
Biological
Insulating
Liquids
New Insulating Liquids for High Voltage
Engineering
Biological Insulating Liquids
· ·
Ernst Peter Pagger Norasage Pattanadech
·
Frank Uhlig Michael Muhr
Biological Insulating Liquids
New Insulating Liquids for High Voltage
Engineering
ErnstPeterPagger NorasagePattanadech
EPPConsultingGmbH ElectricalEngineeringDepartment
Vienna,Austria SchoolofEngineering
KingMongkut’sInstituteofTechnology
FrankUhlig Ladkrabang
GrazUniversityofTechnology Bangkok,Thailand
Graz,Austria
MichaelMuhr
GrazUniversityofTechnology
Graz,Austria
ISBN 978-3-031-22459-1 ISBN 978-3-031-22460-7 (eBook)
https://doi.org/10.1007/978-3-031-22460-7
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Preface
Mineral oil, silicon oil, synthetic ester and natural ester—what do they have in
common?Alltheseliquidscanbeandareusedasinsulatingliquidsinhigh-voltage
engineering.Insomepoints,theirbehaviorisverydifferent.Thebookshouldprovide
the reader above all with information about Biological Insulating Liquids used in
transformercoolingcomparedtootherinsulatingliquids.Transformersarecritical
andexpensivepiecesofequipmentinthepowergenerationanddistributionnetwork.
Anyfailurecouldhavedrasticconsequencestoanentireelectricalnetwork.
Environmental friendliness, riskreduction and, above all, sustainability are key
wordsthatarecurrentlyshapingthetransformationintheenergyindustry.Ofpartic-
ularimportancearetheusedmaterialsregardingtotheelectricalequipment.Driven
by climate change and global warming, the industry has to look in all fields of
their activities to find sustainable solutions and reducing the use of fossil fuels
to a minimum. Biological, renewable insulating liquids have a number of bene-
fitscombinedwithaverysmallcarbonfootprint.Someofthemalreadyusedinthe
high-voltageengineeringandothergreatcandidatesforreplacingmineraloilarein
thepipeline.
Thefirstliquidfilledtransformerswerenotfilledwithmineral;theywerefilled
withvegetableoil.Butbecauseofthebadoxidationstabilityofthepurevegetable
oils,themissingofsealeddevicesandantioxidants,manufacturesswitchedtomineral
oil.Mineraloilisalreadyusedforapproximately100yearsasinsulatingliquidandis
stilltheliquidwiththewidestutilization.Inthe1970s,mixturesofpolychlorinated
biphenyls (PCBs) were because of their non-flammable nature and their chemical
stabilitythehighlightonthemarketoftransformerliquids.Polychlorinatedbiphenyls
were widely used for about fifty years under a variety of trade names, the most
commonofwhichwereAskarel®.Aschemicallystable,polychlorinatedbiphenyls
wouldonlyslowlybiodegrade.Thatisthattheytendedtopersistinnatureasopposed
todecomposingintobasicelements.Innumeroushealthstudies,theirnegativeeffects
onbothhumansandwildlifeweredocumented.Duringthe1980sand1990s,agreat
deal of time, money and effort was necessary to retro-fill transformers with more
acceptableliquids.
v
vi Preface
Inthelate1970s,GeneralElectricwenttomarketwithatransformerdesigncalled
‘Vaportran’.VaportranusedadielectriccoolantcalledR-113,alsoknownas‘Freon’.
Freonwasaveryeffectivecoolinginsulatingliquid.Inthetransformertank,itwasin
liquidstate,andthen,theheatfromthewindingsvaporizestheliquid,andfinally,the
vaporiscondensedintheheatexchangeragain.Aftergettingknowledgeoftheprob-
lemswithpolychlorinatedbiphenyls,thiswasaneffectivereplacementforPCBdue
toitsperformancecharacteristicsandnon-flammablenature.Withglobalconcerns
about damage to the ozone layer, Freon is being phased out worldwide. Nearly,
the same happened to hexafluoride (SF ). Nowadays, widely used in switchgears,
6
circuit-breakers and transformers, it will be panned by the European Commission
as its global warming potential is approximately 23,000 times higher compared to
carbon dioxide. These are examples where enthusiasm had to give way to reality
onceagain.
Siliconeoilwasforseveraldecadesthefluidofchoicewhenlessflammabledielec-
tricliquidwasdesired.Ithasarelativelyhighfirepointandisgenerallyconsidered
toself-extinguishwhenthesourceofafireisremoved.Buttheliquidisnotmiscible
withconventionalmineraloil,notbiodegradableandveryexpensive.
Theseexamplesshowthatyoumustbeverycarefulwhenswitchingtonewinsu-
latingliquidsandtohaveconsiderallsideeffects;otherwiseitiseasytocomeout
ofthefryingpanintothefire.
Because of sometimes large amounts of insulating oil and direct contact with
high-voltage elements, power transformers filled with mineral oil are one of the
mostdangerousdevices.Firesintransformersfilledwithmineraloil,insomecases
with many dead people, are evidence of this. Synthetic—and natural ester filled
transformers are due to the higher fire point of the liquid much saver. Synthetic—
andnaturalestersarealsoenvironmentallyfriendly;hence,theyarebiodegradable.
Thebasisofthenaturalestersisofvegetableorigin(wheat,soy,sunflower,castor,
palmoil,peanutoil,rapeseed,etc.).Thisalsoopensthediscussionabouttheuseof
foodforindustrialpurposes.Wemusttakethisintoaccountinallourdeliberations
very carefully. One way is to use non-edible vegetable oils. An assessment and
estimationoftheeffectsontheecologyandhowthiscanbeminimizedisnecessary.
Otherwise,thesamethinghappensthathasbeenshownwithsomeoftheinsulating
liquids listed above; they will disappear from the market for a short or long time.
Regardingtheentireroutefromthecradletothegraveandweighingupallthepros
andcons,theBiologicalInsulatingLiquidsshowasensiblealternativetotheother
insulatingliquids—abovealltomineraloilliquids.
Thedifferentpropertiesofthedifferentinsulatingliquidsalsoinfluencethedesign
ofthedevicesandmustbetakenintoaccountaccordingly.
Vienna,Austria ErnstPeterPagger
Bangkok,Thailand NorasagePattanadech
Graz,Austria FrankUhlig
Graz,Austria MichaelMuhr
Contents
1 Introduction ................................................... 1
References ..................................................... 9
2 DielectricInsulatingLiquids .................................... 11
2.1 MineralOil ............................................... 12
2.2 Bio-basedHydrocarbonInsulatingLiquid ..................... 13
2.3 EsterLiquids ............................................. 13
2.3.1 SyntheticEster .................................... 17
2.3.2 NaturalEster(VegetableOil) ........................ 19
2.4 SiliconOil ............................................... 34
2.5 IodineNumberofDifferentInsulatingLiquids ................. 35
2.6 ContentofHalogensofDifferentInsulatingLiquids ............ 36
2.7 Additives ................................................. 36
2.7.1 Antioxidants ...................................... 36
2.7.2 PourPointDepressant .............................. 44
2.7.3 Passivator ......................................... 46
References ..................................................... 48
3 ProductionProcessofDielectricLiquids .......................... 51
3.1 MineralOil ............................................... 51
3.2 EsterLiquids ............................................. 52
3.2.1 SyntheticEster .................................... 54
3.2.2 BiologicalInsulatingLiquids(NaturalEsters) .......... 55
3.2.3 MethylEsterLiquidsStemmingfromVegetableOils .... 60
3.3 Bio-basedHydrocarbonLiquids ............................. 63
3.4 SiliconeOil .............................................. 63
References ..................................................... 64
4 PropertiesofNewInsulatingLiquidsandMainDifferences ........ 65
4.1 ChemicalProperties ....................................... 65
4.1.1 NeutralizationNumber ............................. 66
4.1.2 AgingStability .................................... 70
vii
viii Contents
4.1.3 GassingTendency ................................. 74
4.1.4 GasSolubility ..................................... 76
4.2 PhysicalProperties ........................................ 77
4.2.1 Density ........................................... 77
4.2.2 Viscosity ......................................... 81
4.2.3 Interfacial–SurfaceTension ......................... 87
4.2.4 WaterAbsorptiveCapacity .......................... 90
4.2.5 MiscibilityofAlternativeInsulatingLiquids ........... 94
4.3 ThermalProperties ........................................ 97
4.3.1 FlashPoint—TestMethod ........................... 101
4.3.2 FirePoint—TestMethod ............................ 102
4.3.3 HeatingValue—TestMethod ........................ 102
4.3.4 SpecificHeatCapacityandThermalConductivity ...... 102
4.3.5 DecompositionProductsinTechnicalUse ............. 106
4.3.6 PourPoint ........................................ 106
4.4 ElectricalProperties ....................................... 108
4.4.1 DielectricConstantandRefractivity .................. 109
4.4.2 BreakdownVoltage ................................ 114
4.4.3 Dielectric Breakdown Voltage Under Impulse
Condition ......................................... 118
4.4.4 DielectricDissipationandPowerFactor ............... 121
4.4.5 VolumeResistivity ................................. 124
4.4.6 PartialDischargeBehavior .......................... 125
4.4.7 ElectrostaticChargingTendency(ECT) ............... 126
4.5 EnvironmentalProperties ................................... 130
4.5.1 BiologicalProperties ............................... 130
4.5.2 EcologicalProperties ............................... 133
4.6 InteractionwithTransformerMaterials ....................... 134
4.6.1 CorrosiveSulfurContamination ...................... 134
References ..................................................... 135
5 Application of New Insulating Liquid in High Voltage
Equipment .................................................... 141
5.1 General .................................................. 142
5.2 InteractionwithOtherTransformerMaterials .................. 143
5.2.1 InteractionBetweenSolidandLiquidInsulation ........ 144
5.2.2 ElectricalChargingTendency ........................ 156
5.3 DegradationMechanismofInsulationSystems ................ 156
5.4 TransformerDesign ....................................... 157
5.4.1 RiskAnalysis ..................................... 160
5.4.2 TemperatureMonitoring ............................ 165
5.4.3 BiologicalLiquids—AccompaniedTests .............. 167
5.4.4 OxidationStability ................................. 171
5.4.5 AcceleratedAging ................................. 171
5.4.6 TransportofLostEnergy(HeatTransfer) .............. 173
Contents ix
5.4.7 ColdTemperatureBehavior ......................... 176
5.4.8 ElectricalStress ................................... 176
5.4.9 SwitchingTechnology .............................. 183
5.4.10 DielectricResponseMeasurement .................... 186
5.4.11 SustainablePeakLoadTransformers .................. 186
5.5 ConditionMonitoringandDiagnosis ......................... 186
5.5.1 MeasurementAccuracy ............................. 187
5.5.2 InsultingLiquidSampling ........................... 188
5.5.3 Color ............................................ 189
5.5.4 AcidNumber ...................................... 189
5.5.5 InterfacialTension ................................. 190
5.5.6 PourPoint ........................................ 191
5.5.7 Viscosity ......................................... 191
5.5.8 WaterContent ..................................... 191
5.5.9 DissipationFactor ................................. 192
5.5.10 VolumeResistivity ................................. 192
5.5.11 DissolvedGasAnalyzes ............................ 192
5.5.12 DegreeofPolymerization ........................... 216
5.5.13 Vibro-AcousticMeasurement ........................ 217
5.6 Passivators ............................................... 218
5.7 TransformerDielectricLiquidRegeneration ................... 219
5.7.1 Reconditioning,Regeneration-ReclamationProcess ..... 220
5.8 EconomicandEcologicalConsideration ...................... 223
References ..................................................... 225
6 AdvancedResearchintheFieldofBiologicalInsultingLiquids ..... 231
6.1 CorrosionCausedbytheInsulatingLiquid(CorrosiveSulfur) .... 232
6.1.1 SampleTreatmentwithAirandNitrogen .............. 233
6.1.2 SampleTreatmentwithSulfurCompounds ............ 233
6.1.3 Degradation of Dibenzyl Disulfide (DBDS)
ThroughThermalTreatment ......................... 241
6.2 Interaction with the Solid Insulation (Paper) During
anAgingTest ............................................. 243
6.2.1 FuransProductionDuetoAging ..................... 244
6.2.2 FuransTransportandDistributionDuetoAging ........ 245
6.2.3 ChangeofTotalAcidNumberDuetoAging ........... 246
6.2.4 ModificationsinIRSpectrumDuetoAgingTest ....... 248
6.2.5 ChangeofDegreeofPolymerizationDuetoAging
Test .............................................. 249
6.2.6 ChangeofBreakdownVoltageDuetoAgingTest ...... 249
6.2.7 ChangeinInterfacialTensionDuetotheAgingTest .... 250
6.2.8 ChangeinViscosityDuetotheAgingTest ............ 251
6.3 MoistureTransportBetweenInsulatingLiquidandSolid
Insulation ................................................ 252
6.3.1 ImpregnationoftheSolidInsulation .................. 254
x Contents
6.3.2 Preparing and Treatment of Samples After
ImpregnationforMoistureTransport ................. 257
6.3.3 ResultsofMoistureTests ........................... 258
6.4 VibrationandNoise ....................................... 264
6.5 TheEffectofNanoparticlesinBiologicalInsulatingLiquids ..... 266
6.5.1 EffectsonACBreakdownandResistivity ............. 268
6.5.2 EffectsonPartialDischargeCharacteristics ............ 269
6.6 DielectricBehavioroftheLiquidBoardInsulationUnder
DirectVoltageStress ....................................... 273
6.6.1 Electrical Conductivity in Liquid Immersed
CelluloseInsulationSystem ......................... 275
6.6.2 MeasurementofElectricalConductivity ............... 278
6.7 OperationofEquipmentwithBiologicalInsulatingLiquids ...... 279
6.7.1 SustainablePeakLoadTransformer .................. 279
6.8 ExaminationofElectricallyStressedInsulatingLiquids ......... 285
6.8.1 StreamerPropagationinCaseofLightningImpulse ..... 285
6.8.2 DGAfromSwitchingandLightningImpulseTest ...... 286
6.8.3 ACBreakdownTestswithPalmOil .................. 288
6.8.4 Electrical Tests of Natural Ester Impregnated
Pressboards ....................................... 290
6.8.5 BreakdownVoltageTestsUnderColdCondition ....... 293
6.8.6 Dissolved Gas Analyzes of Electrical Fault
SimulationofNaturalEsterInsulatingLiquids ......... 294
6.9 ComparingtheDielectricBehaviorofDifferentInsulating
LiquidsinSolidInsulation .................................. 295
6.9.1 DCConductivityofSolidImpregnatedwithEster
Fluids ............................................ 296
6.10 RetrofillofMineralOilFilledEquipmentwithBiological
InsulatingLiquids ......................................... 297
6.10.1 TransformerSelectionforRetrofilling ................ 300
6.11 AdvantagesofBiologicalInsulatingLiquids .................. 300
References ..................................................... 301
7 Standardization ................................................ 305
References ..................................................... 307
8 Conclusion .................................................... 317
8.1 Advantages When UsingBiological InsulatingLiquids
(Summary) ............................................... 319
8.2 DisadvantagesWhenUsingBiologicalInsulatingLiquids
(Summary) ............................................... 320
8.3 Comparison of Applicability Performance of Different
InsulatingLiquids ......................................... 320