What is an Insulating Material : Classification & Its Applications

An Electrical Insulating Material/Insulating Material is used to obstruct the flow of current. It forms ionic bonds and the materials that have low conductivity and high resistivity are available in the form of solid, liquid, gaseous like the plastic used for plugs, insulating oil used in transformer, etc. These materials have very high resistance so the flow of electric current requires an extremely high voltage like kilo or megavolts to send a few milliamperes of current to them. The insulators are used primarily for storage and also in all domestic and commercial electrical equipment to isolate the conductor from the earth.

What is Insulating Material/Electrical Insulating Material?

The Electrical Insulating Material/insulating materials are the materials that inhibit heat transmission, electric current, or noise. All the insulating materials have a negative temperature coefficient of resistance and as such resistivity is reduced with an increase in temperature. The function of the insulator is very important without which no electrical machine can work, the majority of the breakdown in the field of electrical engineering is due to the failure of insulation. The importance of the insulating materials is ever-increasing in day by day as there is an innumerable number of types of insulators available in the market. The selection of the right type of insulating matter is very important because the life of the equipment depends on the type of material used.

Basics of Insulating Material

The insulators are the materials that have the valence electrons eight or nearer to eight. When the valence electrons are eight obviously the atom is in a stable condition and they offer very high resistance as there are no free electrons, also the forbidden gap between conduction and valence band is more. The atomic structure of insulating material neon is shown in the below figure.

As shown in the above figure, that atom has eight electrons in the outermost orbit, hence they are stable and it can be considered as an insulator. The atomic structure of fluorine has seven electrons in their outermost orbit in a valence electron. The atomic structure of insulating material fluorine is shown in the below figure.

 

The atoms like oxygen which have only six electrons in a valence electron they can be classified also as an insulator but the insulating properties of oxygen are less than that of fluorine and neon.

The atoms having eight electrons and seven electrons in an outermost orbit behave as good insulator compared to the atoms having six valence electrons.

What is Glass Insulator?

At high temperature, the glass insulators are designed or manufactured by mixing the different types of materials, including quartz and lime powder, and then cools in the mold. The main disadvantage of the glass insulator is, compared to the other type of insulators the contaminations are observed easily by the glass insulator and on the surface of the glass insulator, the moisture can be distilled easily.

Properties

The properties of the glass insulator are

• Dielectric Strength: The approximate value of dielectric strength is 140 kV/cm.
• Compressive Strength: The approximate value of compressive strength is 10,000 Kg/cm².
• Tensile Strength: The approximate value of tensile strength is 35,000 Kg/cm².

Advantages

The advantages of the glass insulator are

• Compare to porcelain the dielectric strength is very high in a glass insulator
• High resistivity
• The tensile strength is higher than porcelain
• It is cheaper than porcelain insulator
• Less cost

What is Polymer Insulator?

The polymer or polymeric insulator is also known as a composite insulator. It is a light-weight insulating material and has high mechanical strength. The disadvantage of the polymer insulator is if there is any unwanted gap between weather shed and core their moisture may enter.

Properties

The polymeric or polymer insulator has excellent properties they are hydrophobicity, lightweight, and anti-weather ability.

Advantages

The advantages of the polymer insulator are

• Compare to porcelain and glass insulator the polymer insulator is very lightweight
• Installation cost is low
• Tensile strength is higher than porcelain
• Better performance

What is a Porcelain Insulator?

The porcelain insulator is an aluminum silicate insulating material. In the present day, this material is used for the overhead insulator. The week in tension and poor shock resistance is the disadvantages of a porcelain insulator. The porcelain can also be called as ceramic. The applications of this insulator are distribution and transmission lines, isolators, transformer bushings, fuse units, plugs, and sockets

Properties

The properties of the porcelain insulator are

• Dielectric Strength: The approximate value of dielectric strength is 60 kV/cm.
• Compressive Strength: The approximate value of compressive strength is 70,000 Kg/cm². 
• Tensile Strength: The approximate value of tensile strength is 500 Kg/cm².

Advantages

The advantages of the porcelain insulator are

• Compared to glass insulator the mechanical strength of porcelain insulator is very high
• Leakage current is low
• It is less affected by temperature
• Long life
• Easy to maintain
• Highly Flexible
• Highly reliable

Properties of  Insulating Material

All the insulators when used should not only behave as an insulator over a wide range of electric voltage but must strong mechanically. They shouldn’t be affected by heat, atmosphere, chemical effects and should be free from deformation due to aging. Therefore before selecting an insulating material, it is quite essential to know the various properties and their effects on insulation. The various properties of insulating materials are electrical properties, visual properties, mechanical, thermal, and chemical properties.

Electrical Properties

 The electrical properties of insulating materials are divided into two types they are insulating resistance and dielectric strength. The insulating resistance is again classified into two types they are volume resistance and surface resistance. The factors affecting insulating resistance are temperature, aging, applied voltage and moisture and the factors affecting dielectric strength are temperature and humidity.

Visual Properties

The visual properties of insulating material are appearance, color, and its crystallinity.

Mechanical Properties

Some of the mechanical properties which are to be taken care of while selecting the insulating material are tension & compression, resistance to abrasion, tear, shear & impact, viscosity, porosity, solubility, moisture absorption, and machinability and mouldability.

Thermal Properties

The thermal properties of insulating material are melting point, flash, volatility, thermal conductivity, thermal expansion, and heat resistance.

Chemical Properties

The various chemical properties of insulating material are resistance to external chemical effects, effects on other materials, chemical changes in the material, hygroscopicity, and aging.

Classification of  Insulating Material

The classification of insulating material is based on the thermal classification, physical classification, structural, chemical classification, and the process of manufacture.

Thermal Classification

Thermally the insulators are classified into seven types or seven classes they are class-Y, class-A, class-E, class-B, class-F, class-H, and class-C.

Class-Y

The class-Y limitation temperature is 90°C and the materials come under class-Y are cotton, paper, silk, and similar organic materials.

Class-A

The class-A limitation temperature is 105°C and the materials come under class-A are impregnated paper, silk, polyamide, cotton, and resins.

Class-E

The class-E limitation temperature is 120°C and the materials come under class-E are enameled wire insulation on the base of powdered plastics, polyvinyl epoxy resins, etc.

Class-B

The class-B limitation temperature is 130°C and the materials come under class-B are inorganic materials impregnated with varnish.

Class-F

The class-F limitation temperature is 155°C and the materials come under class-F are mica, polyester epoxide varnished in the high heat resistance.

Class-H

The class-H limitation temperature is 180°C and the materials come under class-H are composite materials on mica, glass, fiber, etc.

Class-C

The class-C limitation temperature is >180°C and the materials come under class-C are glass, mica, quartz, ceramics, Teflon, etc

Physical Classification of Insulating Material

The physical classification of insulating material is classified into three types they are solid, liquid, and gaseous. The physical classification of insulators is shown in the below figure.

The solid insulating materials are fibrous, ceramic, mica, glass, rubber, and resinous. The liquid insulating materials are mineral oils, synthetic oils, transformer oils, and miscellaneous oils. The gaseous insulating materials are air, hydrogen, nitrogen, and Sulphur hexafluoride.

Structural Classification

The structural classification of insulating material is classified into two types they are cellulose and fibrous.

Chemical Classification

The chemical classification of insulating material is classified into two types they are organic and inorganic.

Process of Manufacture

The process of manufacture is classified into two types they are natural and synthetic.

Some of the insulating materials are fiberglass, mineral wool, cellulose, natural fibers, polystyrene, polyisocyanurate, polyurethane, insulation facings, phenolic foam, urea-formaldehyde foam, etc.

Applications of  Insulating Material

The applications of insulating material are

• Cable and transmission lines
• Electronic systems
• Power systems
• Domestic portable appliances
• Electrical cable insulating tape
• Personal protective equipment
• Electrical rubber mats

FAQs

1). What are the common insulating materials?

Some of the common insulating materials like ceramic, glass, Teflon, silicone, etc.

2). Which materials are used to insulate wires?

Some of the best good electrical insulating materials are glass, paper, Teflon, PVC, varnish, and rubber.

3). What are the common thermal insulator materials?

The common thermal insulating materials are mineral wool, fiberglass, polystyrene, cellulose, polyurethane foam, etc.

4). What are the applications of insulating materials?

The applications of insulating material are electrical rubber mats, power and electronic systems, cable and transmission lines, etc.

5). What is the importance of insulating materials?

The selection of the right type of insulating material is very important because the life of the equipment depends on the type of material used.

In this article what are insulating materials/electrical insulating materials, classification of insulating materials, applications, advantages and properties of glass insulation, porcelain insulator and polymer or polymeric insulator, properties of insulating materials are discussed. Here is a question for you what type of insulating materials are used in the home?