Electrical Insulators and it's types

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The electrical insulator is a device that provides the required insulation between the line conductor and earth. Due to this insulation, leakage current can’t flow from the line conductor to earth. Insulator a material or a device which restrics the flow of free electrons (or charge). 
The successful operation of an overhead line depends to a considerable extent upon the proper selection of insulation. 

Importance of Electrical Insulators-

  1. The insulator work as a Protector or Protective device. Because it provides high resistance.
  2. Insulator helps to protect from heat, noise, and electricity.
  3. The insulator is used to support the overhead conductor.
  4. It is commonly used to insulate the live parts of equipment or conductor from the earth.
  5. The live conductor is protected by wrapping the insulation.
  6. It helps to protect switchgear, transformers.

Properties of Electrical Insulator-

  1. The electrical insulator has a high resistivity.
  2. Insulator has good mechanical strength for the conductor load.
  3. It has good dielectric strength.
  4. It has a high relative permittivity of insulator material.
  5. The material used in the insulator is waterproof or non-porous.

Insulators are classified into six different major types.

  1. Pin Insulator
  2. Strain Insulator
  3. Shackle Insulator
  4. Suspension Insulator
  5. Post-Insulator
  6. Stay Insulator.

1. Pin Insulator


Pin Insulator
The pin types of insulators are mostly used in the distribution system. It insulates a wire from physical support such as a pin (wooden or metal dowel) on a utility pole

Specification of Pin Insulator:

  1. Pin insulator can sustain up to 11kV voltage capacity.
  2. It is made up of material which has high mechanical strength.
  3. It can be connected with horizontal as well as vertical position.
  4. This type of insulator is used in the high voltage overhead distribution line.
  5. It requires less maintenance as compared to other insulator types. insulators.

2- Suspension Insulator

Suspension Insulator 
Suspension Insulator
The suspension insulator is called as Disc Insulator. Mostly, suspension insulator is made of glass or porcelain insulating materials.

Specification of Suspension Insulator:

  1. The voltage operating capacity of the insulator is from 11 kV to 765 kV.
  2. It is mostly used in the overhead transmission system or line.
  3. It provides more flexibility to the overhead line.
  4. The multiple discs can be used based on voltage level (low to high).
  5. It is generally placed with the steel tower.
  6. Suspension insulator requires more height for supporting the multiple discs.

3-Strain Insulator

Strain Insulator 
The strain insulator is similar to the suspension insulator type but it has slightly different working
  1. It is used in higher voltage condition i.e. above the 33 kV.
  2. Primarily, it is used in bend or arm place of the transmission line.

4-Shackle Insulator

Shackle Insulator
Shackle Insulator are small in size, used in low voltage distribution line. This insulator can be used in both vertical and horizontal positions.

Specification of Shackle Insulator:

  1. In the distribution line, the metallic strip is used to connect the shackle insulator.
  2. This insulator has a bearing capacity up to the 33 kV voltage.
  3. In the circular turn or bend position, a shackle insulator can work.

5. Post-Insulator

Post Insulator 
Post insulators are commonly used in the substation or generating substation because it is suitable for different voltage levels and ensures stable distribution of electricity.

Specifications of Post Insulator:

  1. In a substation, it is suitable for different voltage levels (from a higher to lower voltage).
  2. It is always placed in a vertical position.
  3. It helps to protect switchgear, transformers, and other connecting devices.
  4. This type of insulator has strong mechanical strength

6. Stay Insulator

Stay Insulator 
It is a type of low voltage insulator designed to counterweight and fasten dead-end poles by combining a stay wire or main grip. They are rectangular or oval in shape.

Specification of Stay Insulator:

  1. Stay insulator is used only in the distributions line.
  2. It occurs in small size as compared to other insulators.
  3. It always places in between the line conductor and earth.

Dipashri Patil 

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