What is Disc Insulator : Types & Its Applications

If we observe the electrical overhead system outside, it includes different electrical components like an insulator, conductor, and tower or electrical pole. This overhead system is used for transmission as well as the distribution of electricity. An insulator is an electrical device, used to provide the insulation among the line conductor & earth to stop the leakage current. So insulating material plays an essential role while making different circuits & power systems. It gives high resistance so that the electrical current doesn’t supply from one place to another. There are different types of insulators are used in transmission & distribution systems like pin, strain, shackle, post, stay and disc insulator. This article discusses an overview of disc insulator and its types.

What is a Disc Insulator?

Definition: An insulator that is made up of high-grade wet processes like brown-green glazed is known as disc insulator. These insulators are used in transmission & distribution systems. The designs of these insulators mainly change based on customer requirements. The properties of every electrical insulator include the following.

Disc Insulator
Disc Insulator
  • High resistivity
  • Mechanical strength should be good for the conductor load.
  • Dielectric strength is good
  • For insulation material, its relative permittivity is high.
  • It uses materials like non-porous or waterproof.

The designing of these insulators can be done using different materials based on the application such as rubber, plastic, wood, mica, glass, etc. The exact insulating materials used in an electrical system are glass, porcelain, steatite, ceramic, polymer, PVC, etc. But, in electrical power systems, the insulators with porcelain material are the best and used in transmission & distribution system. Glass type materials are used in strain/ suspension type insulators.

Types of Disc Insulators

Disc insulators are classified into types which include suspension type and strain type.

Suspension Type Insulator

In suspension insulator, the conductor can be hanged under the support point. These types of insulators are available in two types namely connected cap type & interlinking/ Hewlett type insulators. These insulators are available at low-cost compare with pin type insulator and these are flexible and reliable more.

Suspension Insulator
Suspension Insulator

Strain Type Insulator

This kind of insulator is also known as a tension insulator. These insulators are utilized in overhead electrical wiring for supporting overhead power lines & radio antennas. The discs are connected in a horizontal position. For a long period, several strain insulators are used by connecting them in parallel. In this case, two strings are connected through two yokes.

Strain Type Insulator
Strain Type Insulator

Advantages and Disadvantages of Disc Insulator

The advantages of disc insulators include the following.

  • This type of insulator has a normal voltage rating like 11KV, so a suspension string can be designed with a set of discs.
  • In suspension insulators, if anyone of the discs is damaged then it can be changed much simply.
  • Mechanical pressures on this insulator are less due to the hanging line on an elastic suspension string.
  • This kind of insulator is used at any high voltage by connecting discs separately
  • Repair is reasonable as simply damage unit can change.
  • It protects from noise, electricity, and heat.
  • It gives support to the overhead conductor.
  • In a substation, it protects the transformer, switchgear, etc.

The disadvantages of disc insulators include the following.

  • The string of this insulator is expensive compare with post and pin type insulators.
  • It needs more height for supporting structure and also to maintain similar ground permission of the current conductor.
  • It needs a cross arm with a high length.
  • The tower’s weight must be high to withstand the insulator’s weight.


The applications of disc type insulators include the following.

These insulators are used in transmission & distribution lines


1). What is the difference between pin and post type insulator?

Pin type is used up to 33KV system whereas the post type is used in high & low voltage systems.

2). How disc insulators are made?

These are made with a high-grade wet process like Brown Green Glazed

3). What is an insulator?

The current doesn’t flow through the substance is known as an insulator.

4). What are the types of disc insulators?

They are suspension and strain/tension.

5). What is the best insulator in the world?

Aerogel insulator is best due to less thermal conductivities in an atmosphere like 0.03 W/m*K.

Thus, this is all about an overview of disc insulator which includes types, disc insulator working, advantages, disadvantages and it’s applications. These insulators are used for above 33kv in terminal & section towers for high voltage lines. The designing of this can be done with the help of porcelain by connecting disc separately through the metal link. Here is a question for you, what is disc insulator calculation?