Insulating material

An insulating material (also insulating material ) is a non-conductive material in the technical language , which therefore has only an extremely low and thus negligible electrical conductivity . Insulation materials are used in the electrical engineering used to the flow of electrical current to the live limiting parts. Insulators (e.g. for cables ) are made from insulating materials (also called insulation).

In everyday life, the term insulation material generally means all insulation materials that are intended to hinder the transfer of energy or substances, for example heat ( thermal insulation ), sound ( sound insulation ) or water vapor (e.g. paints ) and water ( building waterproofing ).

Electrical insulating materials

Ceramic high voltage insulator

Electrical insulating materials have a high specific electrical resistance (min. 10 ¹⁰  Ω · cm) and are non-conductors. They are also characterized by a high dielectric strength and a low water absorption capacity . Further requirements are mechanical strength and resistance to environmental influences, depending on the area of ​​application.

Important properties are high tracking resistance and thermal load capacity. The thermal load capacity is indicated by insulation classes.

In contrast to electric current , electromagnetic fields (depending on frequency and wavelength ) can penetrate insulation materials to different extents, so if these are not desired, cables must be additionally screened .

One of the first technically used electrical insulation materials in the middle of the 19th century was gutta-percha , the dried milky sap of the gutta-percha tree native to the Malay region , which was used in the area of ​​the telegraph lines that were being built at that time .

Insulating materials mostly used today are plastics ( thermoset , thermoplastic , elastomers ), technical ceramics , insulating oil , oil-soaked paper, glass.

Examples

Core insulation made of mineral fibers (fire protection cable)

• Technical ceramics , e.g. B .:
  • Steatite , porcelain ( insulators , current feedthroughs)
  • Aluminum oxide ceramic
• Thermoplastic , e.g. B .:
  • Polyethylene or PE ( coaxial cable , telephone and network cable )
  • cross-linked polyethylene or VPE ( high voltage cable )
  • Polyvinyl chloride or PVC (low voltage cable)
  • Polytetrafluoroethylene or PTFE (highly stressed, low-loss cables and components, high-frequency insulators)
  • Polyester (PES) or polycarbonate (PC) (cables, capacitors , insulation for winding wires )
• Thermosets , e.g. B .:
  • Hard paper ( printed circuit board base material), phenoplast (housing and terminals)
  • Hard tissue ( electric motors and generators)
  • Epoxy resin ( potting, sheaths) and epoxy resin fiber composites ( printed circuit board base material)
  • Melamine resin ( aminoplast )
  • Polyurethane resin (paints, potting components, insulation for winding wires )
• Elastomers
  • Silicone elastomers (composite insulators, coatings for ceramic insulators)
  • Ethylene propylene copolymer (cable insulation)
• Oils
  • Silicone oil
  • Chlorodiphenyl (no longer permitted)
  • Transformer oil in circuit breakers , power transformers , power capacitors , oil-filled cable .
• Electrical insulation paper
• Glass
  • Borosilicate glass
  • Aluminosilicate glass
• mica

Supra-isolator effect

Similar to superconductors , at temperatures around absolute zero there is the effect that the electrical resistance of some (supra) insulators increases by several orders of magnitude. This can be increased up to the complete disappearance of the electrical conductance, such materials are also known as Supra insulator (engl. Superinsulator ).

Overload damage

Every real insulating material can only insulate up to a certain voltage and temperature. See: Isolator: Overload Damage

Individual evidence

1. ^ Karl Küpfmüller, Wolfgang Mathis, Albrecht Reibiger: Theoretical electrical engineering: An introduction . Springer-Verlag, 2013, ISBN 978-3-642-37940-6 , pp. 263 ( limited preview in Google Book Search [accessed September 8, 2016]).
2. ↑ Otfried Georg: Electromagnetic fields and networks: Applications in Mathcad and PSpice . Springer-Verlag, 2013, ISBN 978-3-642-58420-6 , pp. 97 ( limited preview in Google Book Search [accessed June 15, 2016]).
3. ^ Siegfried Hunklinger: Solid State Physics . Walter de Gruyter, 2014, ISBN 978-3-486-85850-1 , p. 592 ( limited preview in Google Book Search [accessed June 15, 2016]).
4. ↑ Hans flushing Beck: Theoretical Electricity: An introduction for students and engineers . Springer-Verlag, 2013, ISBN 978-3-663-04360-7 , pp. 333 ( limited preview in Google Book Search [accessed November 18, 2016]).
5. ↑ Valerii M. Vinokur, Tatyana I. Baturina, Mikhail V. Fistul, Aleksey Yu. Mironov, Mikhail R. Baklanov, Christoph Strunk: Superinsulator and quantum synchronization . In: Nature . tape 452 , no. 7187 , 2008, p. 613–615 , doi : 10.1038 / nature06837 .
6. ↑ Ute Kehse: Sudden Resistance. In: Wissenschaft.de. April 7, 2008, accessed September 8, 2019 . 
7. ↑ William Oburger: The insulating materials in electrical engineering . Springer-Verlag, 2013, ISBN 978-3-662-26196-5 , pp. 10 ( limited preview in Google Book Search [accessed July 20, 2016]).
8. ^ Günther Oberdorfer: Short textbook of electrical engineering . Springer-Verlag, 2013, ISBN 978-3-7091-5062-7 , pp. 75 ( limited preview in Google Book Search [accessed July 20, 2016]).
9. ↑ Eugen Flegler: Problems of the electric breakdown . Springer-Verlag, 2013, ISBN 978-3-663-02856-7 , pp. 10 ( limited preview in Google Book Search [accessed September 8, 2016]).
10. ^ Richard Marenbach, Dieter Nelles, Christian Tuttas: Electrical energy technology: Fundamentals, energy supply, drives and power electronics . Springer-Verlag, 2013, ISBN 978-3-8348-2190-4 , pp. 241 ( limited preview in Google Book Search [accessed January 27, 2017]).