Different Types of Cable Insulators

Electrical Cable can come with insulation or not. There is some type of overhead transmission and distribution cable don’t have insulation on it because it stays up from ground level. But if a cable is passing through ground level and human and animal are crossing nearby then there is a big possibility that anyone can get Electrical Shock if the cable is not having insulation.

Cable Insulators
Cable Insulators

Like cable insulation, a cable insulator is also important equipment in power transmission and distributions system. It keeps safe our transmission and distributions line when the line is active. Cable insulator present between tower to tower. In this post, we will learn Different Types of Cable Insulators.

What is Cable Insulators:

An insulator is one kind of material that prevents the flow of electric current and can be used to support of electrical conductor. The main function of an insulator is to separate the line conductors from the pole and the tower. Normally the conductor of overhead transmission and distribution line is secured by means of the insulator.

It used to prevent the leakage current to the earth through the pole. Jumper safe the line by overloaded. The insulator plays an important role in a successful transmission & distribution for the electrical line. Now the materials most commonly used for an insulator for overhead lines are,

  1. Porcelain
  2. Glass
  3. Steatite
  4. Synthetic


Porcelain is an extensively used material & it produced by firing at very control temperature by a mixture of kaolin, feldspar, and quartz. It is mechanically stronger than the glass. Porcelain surface is not affected by any a kind of dirt deposits and it is less susceptible to changes of temperature.

Porcelain insulator has much dielectric strength and its about 60KV/cm of its thickness. The compressive strength of good porcelain is about 70000 Kg/ cm2 and tensile strength is about 500kg/cm2.

Related: Aluminium Conductor Steel Rein-Forced (ACSR)


The glass is a little bit cheaper than porcelain in the simple shapes and if property toughens and the follow annealed gives resistivity and very high dielectric strength. Glass is quite a homogeneous materials and very high compressive stress. Its very lower coefficient of thermal expansion.

Owing to its transparent nature it can be readily by visual inspection. The main disadvantage of glass is that moisture is easily condensed on its surface.


Steatite is naturally occurring magnesium silicate and it usually found combined with oxides in varying proportion. Steatite has higher tensile and bending stress than porcelain and glass. It can easily be used between tension towers or when the transmission line takes very sharp turns.


Synthetic is non ceramic insulators and its consists of a fiberglass rod covered by weather shed or skirts of the polymer.

Related: Various Types of Electrical Cable Conductor

Now if you find this post useful then please share with your friends. Thanks!

Leave a Reply

Electrical Power Distribution with AUTOCAD, DIALux & Etap

* 8 Hours on-demand Video *