Electrical Insulator

Electrical Insulator Materials

Did it ever occur that items like glass, air, and wood could play a vital role in electrical purposes?  It may come to you as a big surprise, but glass, plastic, paper, cardboard, wood, and even dry air are common electrical insulator materials.  Let us begin with the electrical insulator definition before discussing the properties of insulators and the uses of insulators.

What Is An Electrical Insulator?

Technically, you need to understand the electrical conductor’s concept to master the topic of the electrical insulator, and the application of insulator.  The electrical conductor’s materials enable the flow of the electrical current or charges in a single or multiple directions.  In other words, the conductors of electrical materials can be metals, like copper and non-metallic materials, such as graphite as they have free electrons.  For example, if you want to charge your mobile, you plug it in the socket.  The electrons present in the electrical conductor allow your phone to be fully charged. 

On the contrary, electrical insulator materials do not allow free flow of electric currents or charges.  The electrical insulator materials give very little freedom for the electrons to drift from atom to atom.  Thus, electrical insulators are a poor conductor of electricity.  You can get a better understanding with the help of an electrical conductor example.  You must have observed that the outer covering of your phone charger plug is made from plastic so that the electric charges do not pass on to human skin.  The following is a list of electrical insulator examples.

  • Styrofoam

  • Plastic

  • Wax

  • Rubber

  • Dry air

  • Glass

  • Ceramics

  • Rubber

  • Teflon

  • Mica

  • Quartz

  • Porcelain

  • Asphalt

Uses of Insulators

You must be wondering why are electrical insulators important for us when electric charges cannot be passed through it?  Generally, electrical insulators are highly useful at home, offices, streets, etc.  They are used in electrical appliances and equipment.  Unfortunately, human skin is one of the best conductors of electric charges.   Furthermore, the presence of electrical insulator materials prevents and protects electrical devices from generating high voltage.  There are innumerable uses of insulators.  They are listed below.

  • It prevents the passing of high-voltage in an electric circuit.

  • It helps in reducing the cost of energy.

  • It helps in saving the environment by controlling the emission of pollutants.

  • It improves process performances.

  • It protects from electric shock or electrocution.

  • It allows the soundproofing of appliances.

Application of Insulator

Since the electrical insulator materials bind the electrons tightly, it prevents the electrons from floating from atom to atom.  Thus, they prevent the conduction of electric charges.  Given the benefits of there are multifold applications of the electrical insulator.  They are applied to-

  • Circuit boards

  • Coating of electric wires

  • High voltage appliances

  • Coating of cables

  • Coating for electric poles on the streets

Types of Electrical Insulation In Overhead Lines

Electrical insulators can withstand the charges from electricity.  They are broadly classified into three types of electrical insulation based on their operating voltage levels and applications.

Pin Type Electrical Insulator

A pin insulator is best for supporting low voltage line conductors. A single piece of pin insulator is used in 11kV, and the double piece is applied to 25kV.  Above 44kV, three or four pieces of pin insulators can be used.  An electrical insulator has a porcelain shell.  So even if the outer surface of an electrical appliance gets wet, the inner surface is dry to keep it leakage resistant.

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Suspension Type Electrical Insulator

Suspension electrical insulators are best to handle high-voltage transmission lines.  This type of electrical insulator has porcelain discs inside arranged in a series through metal links such that they have a string-like appearance.  The arrangement of insulators highly depends upon the weather condition, voltage, the size of the insulator, etc.

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Strain Type Electrical Insulator

Another name for strain insulator is tension insulator.  They are best for high voltages when the electrical line is subject to change in the direction of the line, and at higher-tension areas at sharp curves, river crossings, etc.  It is useful in minimizing the excessive tension in the line.   Strain electrical insulators have dielectric properties.  Additional strings can be added when the tension begins to aggravate.

Fun Facts

  1. You would be surprised to know that the diamond necklace you wear on a special occasion is an excellent electrical insulator material.

  2. A high-voltage area, which is dangerous, is enclosed in fiberglass or glass to prevent the conductivity of charges to pass.

  3. Your electrician uses a special screwdriver with a plastic coating to check the passage of electrical charges without getting electrocuted.

FAQ (Frequently Asked Questions)

1. Which properties make an electrical insulator useful?

The job of an electrical insulator is to make high electric charges non-conductive.  Thus, electrical insulator material should have the following properties.

Resistive – When two volt produces 2 amperes of current, the electrical insulator should also produce 1 ohm of resistance.  Thus, electrical insulator materials, such as glass, paper, wood, etc. prevent electrons’ conductivity from passing through. 

Dielectric Strength – The electrical insulator materials should have been mechanically strong to withstand and carry the tension and weight of electrical conductors.  They should be able to provide insulation as well as withstand the pressure without breakdown or failure.


2. Which electrical insulator material is best for performing substantial duty voltage?

Usually, household appliances are found to have a heavy plastic coating to perform the duty of an electrical insulator.  It is because these instruments do not have extremely high-voltage.  The plastic or porcelain insulators are perfect for withstanding free flow of electric currents or charges.  However, factories using heavy machinery require high-voltage.  In such cases, a plastic or porcelain electrical insulator would not suffice.   Glass and mica are more useful insulators for industrial purposes, as it has a high breakdown voltage.   Mica’s dielectric strength is 500 kV/inches, whereas glass has 2000 to 3000 kV/inches dielectric strength, which makes them fit for use in high-voltage industrial uses.