Insulators – Types, Examples, Properties


Insulators are substances which do not allow the flow of current through them. Basically, they are poor conductors of electricity and heat. You can find them to be mostly solid and have a very high resistivity.

In other words, these materials hinder the free flow of electrons from one place to another. Similarly, if we were to transfer a certain amount of charge to any such substance, the charge won’t move and remain at its spot only.



Insulators come in different types. They are mostly used for successfully operating the overhead line. The most common types are:

  • Pin type insulator
  • Suspension type insulator
  • Strain insulator
  • Shackle insulator

Pin Type Insulator

This insulator is secured to the cross-arm on the pole. It is used for transmitting and distributing electrical power.

However, one must not operate it beyond the voltage of 33kv, as it will cause it to be bulky and uneconomical.

Suspension Type Insulator

These are more economical can pin type insulator for a voltage exceeding 33kv. It is more practical because we can replace the disc on damage instead of it becoming completely useless.

Strain Insulator

This insulator is out it when there is a high voltage line. Furthermore, it consists of an assembly of suspension insulators when used in low voltage transmission line. In the vertical plane, the disc of strain insulators is used.

Shackle Insulator

Earlier, the shackle insulator was utilized as strain insulator. However, we also use them in a low voltage line. One can directly fix them to the pole with a bolt or cross arm either horizontally or vertically.

Examples of Insulators

There are many substances which are fine examples of an insulator. They are good at protecting from heat, electricity as well as sound. Some of the examples are glass, quartz, wood, mica, and cloth.

Glass is also one of the finest insulators due to its high resistivity. Furthermore, plastics are also good insulators and used in many things.

Similarly, rubber is a substance which we use in almost everything from car tires to slippers. They are very good insulators.

Properties of Insulators

An insulator consists of many properties which helps it to limit its ability to conduct heat and electricity. Firstly, it has a very high resistance level. It allows it to impede electric current from passing through.

Similarly, it has a breakdown voltage which allows it to lose its insulating abilities. In other words, it will be able to conduct heat and electricity under high voltages.

For instance, the air is otherwise a great insulator but when lightning passes through it, it loses the ability to insulate.

Likewise, different insulators have different breakdown voltages. For instance, ceramic is a fine insulator that has a very high breakdown voltage.

After that, the valence electrons of an insulator hold together tightly. It means that no current is allowed to flow when these electrons are restricted. Similarly, it also impedes the flow of heat.

Moreover, the property of air permeability of insulators is quite important. It refers to the ability of a substance to permit air to flow through its pores.

Thus, substances which are good insulators have higher air permeability. For instance, oven mitt and fibreglass are examples of insulators having very high air permeability.

Solved Question for You

Question– Which of the following substances is not an insulator?

A. Glass
B. Gold
C. Mica
D. Wood

Answer– The correct answer is option B. Gold is not an insulator but a conductor. Furthermore, it does not tarnish and remains conductive for a very long time. Therefore, we refer to it as a very poor insulator.

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