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

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Presentation on theme: "© Prof.Dr.R.Haller Dielectric Properties of Insulation Introduction Basic Relations Modelling of Dielectrics Measurement of Dielectric Parameters Conclusions."— Presentation transcript:

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

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

3 © Prof.Dr.R.Haller Insulation Materials (Dielectrics) gaseous [air, SF 6, N 2, …] liquid [Oil (mineral, silicon,..), H 2 O, 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 ) ?

4 © 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 Properties

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

6 © Prof.Dr.R.Haller Polarization D = ε 0 ·E + P bzw. P = ε 0 ·E·(ε r – 1) = ε 0 ·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 E max ) el. field temperature T

7 © Prof.Dr.R.Haller Relative Permittivity ε r gaseous air, SF 6, N 2, … ~ 1 liquid liquidMineraloil2,2 Siliconoil2,7 Rhizinusoil5 Water81 solid solidPVC4 PE2,4 Polyamid7 Epoxyresin 3,8.. 5,8 Hard- paper 5 paper2,8 Porcelain6 BaTiO

8 © Prof.Dr.R.Haller Electrical Conductivity Electrical Conductivity physically: free movable charged particles (electrons, ions) J = · E = (n + q + b + + n - q - b - + n e q e b e ) technically: depends on material (ions, electrons) pollutions (H 2 O,..) operating parameters (E, t, T)

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

10 © Prof.Dr.R.Haller Dissipation Factor tan δ characterizing of losses (polarization, conductivity) P δ = tan δ · Q c = tan δ · (ωC · U 2 ) depends on ( t (f), E, T) typical values: mineral oil (10 -3 … ) (T = 20 °C) oilimpregnated paper ( … ) ( f = 50 Hz) PVC, PA, paper ( … ) PE, PTFE (10 -4 … ) EP, porcelain (10 -1 … )

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

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

13 © Prof.Dr.R.Haller 5-10 s Materialpolarisation s Grenzschichten s Tree-Strukturen Relaxationszeiten verschiedener Mechanismen insulation

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

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

16 © 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)

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

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

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

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

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

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

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

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

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

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

27 © Prof.Dr.R.Haller R ecover V oltage M easurement S1 A D PC HV DC R U testobject

28 © Prof.Dr.R.Haller Feuchtigkeitseinfluß in papierisolierten Kabeln Anstieg des Maximums bei t m und Verschiebung zu kürzeren Messzeiten Cable m Cable 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

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

30 © 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

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

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

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

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

35 © Prof.Dr.R.Haller Conclusions dielectric properties will be characterized by: relative permittivity ε r electrical conductivity dissipation factor tan δ knowledge of dielectric properties is important for manufacturing, design, operation (diagnosis) and recycling of electrical insulation

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

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


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