Do magnetic insulation materials exist? can we use them in high voltage transmission applications?
To address the issues identified, electrical systems working with high voltages need
specialised insulation to ensure they operate in a safe, stable and reliable way that maximises their useful life. These materials are commonly used in the components, resistors and capacitors in high voltage systems, ensuring the safe transmission of high voltage electricity, as well protecting the system from distorted frequencies which can lead to instability.
Although many different types of insulation material are used in high voltage applications, a strong contender and commonly used material is mica – and we’ll explore why now.
Mica high voltage insulation and its properties
Mica is a mineral with superior electrical, as well as thermal, properties. Mica has a dielectric strength of around 118MV/m, much higher in comparison to other commonly used materials such as silicon, which has a dielectric strength of 20MV/m, and polytetrafluoroethylene (PTFE, most commonly known as Teflon), which has a dielectric strength of 60MV/m. It has other superior electrical properties such as its resistivity and low dielectric loss tangent (or electrical dissipation factor)
Hello Bhupendra Desai ,
The material known as lodestone (magnetite, Fe3O4, is an oxide, which does not conduct electricity) exhibits ferrimagnetism, and is referred to as a ferrimagnet or ferrite; lodestone was the first naturally occurring magnets to be discovered, and was used in ancient compasses. In general, the simplest ferrites are oxides that have a spinel structure with the chemical formula MOFe2O3, where M is a divalent metal ion (Co, Ni, Mn, Cu(II), Fe(II), etc.) You can buy ceramic magnets, which will shatter if dropped on a hard floor and do not conduct electricity, from many vendors, see the Internet.
Regards,
Tom Cuff
Don’t know much about chemical composition not sure about withstanding EHV, though could considered as bad conductor like formation of Al2O3 at aluminum lines…..
Hello Bhupendra Desai and Mohammad Robiul Kabir ,
The chemical composition of ferrimagnets or ferrites can be found in many books [1-2]. As long as the chemical composition of ferrites is stoichiometric, i.e., MOFe2O3, where M is a divalent metal ion and the subscripts are integers - needed to balance the various valences - they do not conduct electricity. However, since ferrites are classed as [defect?] semiconductors, see p. 196 of [2], any nonstoichiometry of the oxygen atoms MOxFe2O3-x , where 0 < x < 1, results in increasing electrical conductivity, which increases with increasing temperature as is the case with all semiconductors; in metals, the electrical conductivity decreases with increasing temperature. In any event, the electrical conductivity of nonstoichiometric ferrites is not "great". Because stoichiometric ferrites have negligible electrical conductivity, they are used as transformer cores in switching power supplies where they exhibit very little eddy current losses compared with, for example, iron cores.
[1] John R. Reitz, Frederick J. Milford; Foundations of Electromagnetic Theory, 2nd. Ed.; Addison-Wesley Publishing Company; 1967; pp. 228-229.
[2] E. W. Lee; Magnetism An Introductory Survey; Dover Publications, Inc.; 1970; pp. 196 & 200.
As far as using Al2O3 as an electrical insulator, this does not answer the original question - as I understand it - because aluminum oxide is only either diamagnetic or paramagnetic, and is not ferromagnetic or ferrimagnetic.
Regards,
Tom Cuff