© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Dielectric Properties of InsulationDielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Dielectric Properties of InsulationDielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Insulation Materials (Dielectrics) gaseous [air, SF6, N2, …]
liquid [Oil (mineral, silicon, ..), H2O, Glycerin, ..]
solid [Cellulose (Paper), Thermoplastics (PVC, PE, …),
Duroplastics (EP, Siliconrubber, ..),
anorganic materials (Porcelain, Ceramics, ..)] which are the most important electrical properties
for manufacturing, design, construction, operation,
diagnosis ( Recycling ) ?
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
electrical strength [kV/mm]
dielectric parameters
permittivity ε
conductivity κ [S/m]
dissipation (loss) factor tanδ
(other) electrical, thermal, mechanical, chemical
parameters
Dielectric PropertiesDielectric Properties
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Dielectric Properties of InsulationDielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
PolarizationPolarization
D = ε0·E + P bzw. P = ε0·E·(εr – 1) = ε0·E· χ
Polarization requests time (relaxation time )
and losses (dissipation factor tan δ)
Polarization depends on material (kind of polarization)
frequency f ) of applied
amplitude Emax ) el. field
temperature T
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Relative Permittivity Relative Permittivity εεrr
gaseousgaseous air, SFair, SF66, N, N22, …, … ~ ~ 11
liquidliquid MineraloilMineraloil 2,22,2
SiliconoilSiliconoil 2,72,7
RhizinusoilRhizinusoil 55
WaterWater 8181
solidsolid PVCPVC 44
PEPE 2,42,4
PolyamidPolyamid 77
EpoxyresinEpoxyresin 3,8 .. 5,83,8 .. 5,8
Hard- paperHard- paper 55
paperpaper 2,82,8
PorcelainPorcelain 66
BaTiOBaTiO33 3000 .. 50003000 .. 5000
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Electrical Conductivity Electrical Conductivity
physically: free movable charged particles (electrons, ions)
J = · E = (n+q+b+ + n-q-b- + neqebe)
technically: depends on material (ions, electrons)
pollutions (H2O, ..)
operating parameters
(E, t, T)
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Electrical Conductivity Electrical Conductivity
typical values: gaseous ( 10-16 …. 10-19 )
(T = 20 °C) liquids/ solids ( 10- 8 …. 10-15 )
Water ( 10- 4 …. 10- 7 )
Semiconductors ( 10+2 …. 10- 7 )
Conductors ( 10+6 …. 10+8 )
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Dissipation Factor tan Dissipation Factor tan δδ characterizing of losses (polarization, conductivity)
Pδ = tan δ · Qc = tan δ · (ωC·U2)
depends on ( t (f), E, T)
typical values: mineral oil (10-3 …. 10-1)
(T = 20 °C) oilimpregnated paper (10- 3 …. 100)
( f = 50 Hz) PVC, PA, paper (10- 2 …. 10-1)
PE, PTFE (10-4 …. 10- 5)
EP, porcelain (10-1 …. 10-2)
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tan tan δδ and and εεrr vs. frequency vs. frequencybiological tissue dispersion area
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tan tan δδ and and εεrr vs. frequency vs. frequency
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
5-10 s Materialpolarisation
conductor
2
311
2
3
30-80 s Grenzschichten
200-500 s Tree-Strukturen
Relaxationszeiten verschiedener Mechanismen
insulation
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inner electrode outer electrode
water tree
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water tree & electrical tree
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Knowledge of dielectric properties is necessary for whole life cycle of electrical equipment
Dielectric properties can be determined by
calculation (modelling, simulation)
measurement ( diagnostic/ testing)
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Dielectric Properties of InsulationDielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Modelling of DielectricsModelling of Dielectricsa) simple circuit
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Modelling of DielectricsModelling of Dielectrics
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Maxwell- Wagner- ModelMaxwell- Wagner- Model
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Modelling of DielectricsModelling of Dielectricsb) complex circuit
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Polarization Effects (i, u)Polarization Effects (i, u)
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Dielectric Properties of InsulationDielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Schering- BridgeSchering- Bridge
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PC- based measuring bridgePC- based measuring bridge
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RVM- and IRC- principleRVM- and IRC- principle
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
RRecoverecoverVVoltageoltageMMeasurementeasurement
S1
AD PCHV
DC
RU
testobject
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Feuchtigkeitseinfluß in papierisolierten Kabeln Anstieg des Maximums bei tm und Verschiebung zu kürzeren Messzeiten
Cable 1 701 m
Cable 2 932 m
time (min)
Return Voltage (V)
Kabel 1: alt gemessen mit 1 kV und 2 kV
Kabel 2: gut gemessen mit 1 kV und 2 kV
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
RVM measurement on 10 kV cabel with paper insulation
Qa: 2,0-1,87 trockenQa: 1,86-1,65 feuchtQa < 1,65 nass
Bewertung des Gradientenim Spannungsanstieg bei 1 und 2 kV :
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
RVM Diagnose an 1 kV Papierkabel - Stromversorgung der Löschwasseranlage eines großen Chemie-Unternehmens
• Speisekabel mit hoher Wichtigkeit für Löschwasserpumpen• 700m Zuleitung im Elbdüker NAKRAA 3x185• T-Muffe und 300 m bzw. 560 m NAKBA 3x185 bis zu den Pumpenhäusern
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Meßprinzip der IRC-MessungMeßprinzip der IRC-Messung
1: Formierung 1800s
I
1kV
CDS
2: Entladung 5s
3: Messung 1800s
testobject
PCAD
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new (normal) aged critical
IRC- Diagnosis on Power Cables
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Measurement of PolarizationMeasurement of Polarization
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Dielectric Properties of InsulationDielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
ConclusionsConclusions
dielectric properties will be characterized by:
relative permittivity εr
electrical conductivity
dissipation factor tan δ
knowledge of dielectric properties is important
for manufacturing, design, operation (diagnosis)
and recycling of electrical insulation
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
ConclusionsConclusions
dielectric properties can be determined by
- calculation / simulation
- measurement/ testing
© Prof.Dr.R.Haller© Prof.Dr.R.Haller
Thank you
Questions ?
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