1. Dielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller

2. Dielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller

3. 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

4. Dielectric Properties
electrical strength [kV/mm]
dielectric parameters
permittivity ε
conductivity κ [S/m]
dissipation (loss) factor tanδ
(other) electrical, thermal, mechanical, chemical
parameters
© Prof.Dr.R.Haller

5. Dielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller

6. Polarization 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

7. Relative Permittivity εr
gaseous
air, SF6, N2, …
~ 1
liquid
Mineraloil
2,2
Siliconoil
2,7
Rhizinusoil 5
Water 81
solid
PVC 4 PE
2,4
Polyamid 7
Epoxyresin
3,8 .. 5,8
Hard- paper
paper
2,8
Porcelain 6
BaTiO3
© Prof.Dr.R.Haller

8. 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

9. Electrical Conductivity 
typical values: gaseous ( … )
(T = 20 °C) liquids/ solids ( … )
Water ( … )
Semiconductors ( … )
Conductors ( … )
© Prof.Dr.R.Haller

10. Dissipation Factor tan δ
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 ( …. 100)
( f = 50 Hz) PVC, PA, paper ( …. 10-1)
PE, PTFE (10-4 … )
EP, porcelain (10-1 …. 10-2)
© Prof.Dr.R.Haller

11. tan δ and εr vs. frequency
biological tissue
dispersion area
© Prof.Dr.R.Haller

12. tan δ and εr vs. frequency
© Prof.Dr.R.Haller

13. Relaxationszeiten verschiedener Mechanismen
conductor 2 1 3
5-10 s Materialpolarisation 1
insulation
30-80 s Grenzschichten 2
s Tree-Strukturen 3
© Prof.Dr.R.Haller

14. outer electrode
inner electrode
water tree
© Prof.Dr.R.Haller

15. water tree & electrical tree
© Prof.Dr.R.Haller

16. Dielectric properties can be determined by
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

17. Dielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller

18. Modelling of Dielectrics
a) simple circuit
© Prof.Dr.R.Haller

19. Modelling of Dielectrics
© Prof.Dr.R.Haller

20. Maxwell- Wagner- Model
© Prof.Dr.R.Haller

21. Modelling of Dielectrics
b) complex circuit
© Prof.Dr.R.Haller

22. Polarization Effects (i, u)
© Prof.Dr.R.Haller

23. Dielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller

24. Schering- Bridge
© Prof.Dr.R.Haller

25. PC- based measuring bridge
© Prof.Dr.R.Haller

26. RVM- and IRC- principle
© Prof.Dr.R.Haller

27. RecoverVoltageMeasurementD PC HV DC R U
testobject
© Prof.Dr.R.Haller

28. Feuchtigkeitseinfluß in papierisolierten Kabeln Anstieg des Maximums bei tm und Verschiebung zu kürzeren Messzeiten
Kabel 1: alt gemessen mit 1 kV und 2 kV
Kabel 2: gut gemessen mit 1 kV und 2 kV
Return Voltage (V)
Cable m
Cable m
time (min)
© Prof.Dr.R.Haller

29. RVM measurement on 10 kV cabel with paper insulation
Bewertung des Gradienten
im Spannungsanstieg bei
1 und 2 kV :
Qa: 2,0-1,87 trocken
Qa: 1,86-1,65 feucht
Qa < 1,65 nass
© Prof.Dr.R.Haller

30. 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
© Prof.Dr.R.Haller

31. Meßprinzip der IRC-Messung
1: Formierung 1800s I
1kV
CDS
2: Entladung 5s
3: Messung 1800s
testobject PC A D
© Prof.Dr.R.Haller

32. IRC- Diagnosis on Power Cables
new (normal) aged critical
© Prof.Dr.R.Haller

33. Measurement of Polarization
© Prof.Dr.R.Haller

34. Dielectric Properties of Insulation
Introduction
Basic Relations
Modelling of Dielectrics
Measurement of Dielectric Parameters
Conclusions
© Prof.Dr.R.Haller

35. Conclusions 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

36. Conclusions dielectric properties can be determined by
- calculation / simulation
- measurement/ testing
© Prof.Dr.R.Haller

37. Thank you
Questions ?
& Answers !
© Prof.Dr.R.Haller