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Types of Insulators Used in Overhead Power Lines

Nov. 10, 2021

The correct choice of the insulator is essential for the successful operation of power lines. There are several types of overhead line insulators. The most commonly used types are

Pin type insulators

Suspension type insulators

Strain insulators

Shackle insulators


Pin insulators

Pin insulators or pin insulators are widely used in power distribution systems with voltage levels up to 33 kV. They are fixed to the cross arms of poles to carry power lines. The top end of the pin insulator has a recess to accommodate the conductor. The conductor is passed through this groove and secured with a bundle of the same conductor as the wire.

20kV Pin Type Composite Insulator

 20kV Pin Type Composite Insulator

Pin-type insulators are usually made of porcelain, but in some cases, glass or plastic can also be used. As pin insulators are almost always used in the open air, proper insulation in the event of rain is also an important consideration.


A composite pin insulator is applicable for high-voltage line facilities. The insulator has good water-repellent, anti-aging, and anti-leakage properties. And it is also featured by high resistance to bending and high mechanical strength. It is easy for installation and the installation dimensions of the top and bottom parts are the same as those of the corresponding porcelain pin type so that they are interchangeable.


Suspension insulators

 For voltages above 33 kV, therefore, suspension insulators are used. Suspension insulators consist of a number of porcelain discs that are connected to each other by metal chains in the form of strings. The wire conductors are suspended from the bottom end of a suspension wire which is fixed to the cross arm of the tower. Each disc in a string of suspension insulators is designed for low voltages, for example, 11 kV. The number of discs in the string depends on the operating voltage. Suspension insulators are the preferred choice for transmission lines.

110kV (132kV) Composite Long Rod Suspension Type Insulator

 110kV (132kV) Composite Long Rod Suspension Type Insulator

Advantages of suspension insulators

Each disc unit is designed for low voltages, e.g. 11 kV. Therefore, depending on the operating voltage, the required number of discs can be connected in series to form a string of insulators suitable for a specific voltage.


If any disc in the insulator string is damaged, it can be easily replaced. There is no need to replace the entire string. In the event of increased line demand, the line voltage can be increased and the additional insulation required to raise the voltage can be easily provided by adding the required number of discs to the insulator string.


As the line conductors are suspended by suspension wires, they run under the grounded cross-arm of the tower. This arrangement provides partial protection against lightning. The suspension arrangement provides greater flexibility for the line. Suspended insulators can be swung so that they can occupy the position of least mechanical stress.

Taporel Electrical Insulation manufactures composite insulator fittings, power line fittings, and other fittings for transmission and distribution lines. Taporel Electrical Insulation produces all kinds of power fittings, including EYE and Clevis, ball and socket, hanging Ring, Y- head, T-head, steel foot, steel cap, flange, and other line accessories. Adhering to "Quality, Service, Integrity", we strictly follow standardized, scientific, and normalized management mode. 

If you want to get more information about the best composite insulator fittings, welcome to contact us today or request a quote.  

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