Insulators to protect electrical devices – some background and history

In my previous post I was talking about waveguides and how they can be used to guide electromagnetic radiation aka light. Now let’s consider the total opposite of it – electric insulators! Enjoy your read and don’t forget to post a comment 🙂Materials that resists an electric current are called insulators. In insulating materials, valence electrons are tightly bonded to their atoms. Insulators separate electrical conductors without allowing current through themselves. Electrical insulation may be the deficiency of electrical conduction. Condensed matter theory outlines that a charge will flow if states are available into which electrons can be excited. This allows electrons to gain energy and thereby undergo a conductor such as a metal. If no such states are available, the material is definitely an insulator.
If certain materials lack other mobile charges for conduction, they are insulators . I.e., if your liquid or gas contains ions, then an ion can be made circulating as a possible electric current, and the material is really conducting. Electrolytes and plasmas contain ions. They will also act as conductors whether or not electron flow is involved. Insulators are popular as a flexible coating on electric wires and cables. Since air is definitely an insulator (ok, at low photon energies before pair creation :)), in principle not one other substance is needed to keep power where it ought to be. In the past, power lines carrying high voltages simply used air as insulator – a solid coating was too impractical. However, wires which touch each other will produce cross connections and short circuits potentially causing fire hazard. In coaxial cables, the center conductor must be supported exactly within the middle of the hollow shield to be able to prevent electromagnetic wave reflections.
Suspended wires for electricity transmission are bare, except where they enter buildings, and so are insulated from the surrounding air. Insulators are needed at the points at which they are supported by utility poles or pylons. Insulators may also be required where the wire enters buildings or electrical devices, such as transformers or circuit breakers, to insulate the wire in the case. Bushings are those hollow insulators with a conductor inside.
The most critical insulation material is air. A variety of solid, liquid, and gaseous insulators may also be found in electrical apparatus. Let us regard small transformers, generators, or electric engines. There, the insulation around the wire coils consists of up to four thin layers of varying insulators. Magnet wires are protected my insulator layers. This allows  permit to obtain impressive numbers of turns for a given volume. Supplemental fiberglass insulator tape are also often used in several designs. Some special Windings can also be equipped with insulators to prevent electrical outburst and reduce wire vibration caused by magnetic fields. Large power transformer windings are still mostly insulated with natural materials like paper, wood, varnish, and mineral oil. Although these materials have been used for a lot more than a century, they still give a good balance of performance over investment. Bus bars and circuit breakers in switchgear may be insulated with glass-reinforced plastic insulation, treated to get low flame spread and also to prevent tracking of current throughout the material.
Electrical insulators, or dielectrics, are materials that can withstand the flow of electrical current. In other words, they are non conducting materials. They are the alternative of electrical conductors that allow electricity to flow through a material. Electrical insulators help coat, protect or support electrical conductors so that the electrical current flows through the conductor. Insulators help to protect given materials and are constructed of substances with electrons, or energy particles that are compressed together by certain chemical processes. It is almost impossible to have electrical voltage to pass through these materials up to higher energies. Some insulators are thought to get higher thresholds for electrical voltage than others do, and so are aptly called high voltage insulators.

Yours,

Cécile

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