With an increase in the operating voltage, the insulation requirement will also increase. Transmission system will have transmission voltages as high as 400kV and above voltage levels. At these voltages, the pin insulators become bulky, cumbersome and costly. You can read about Overhead Line Insulators here. Some of the advantages of suspension insulators over pin type insulators are explained below:
Advantages of suspension insulators over pin insulators
- Suspension insulators are cheaper in cost compared to pin type insulators for operating voltage above 50kV.
- Each unit of suspension insulators (insulator disc) is designed for comparatively low voltage (11kV) and can increase the insulation strength by connecting these insulator disc modules in series. The number of insulator discs requires depends on the operating voltage.
- Suspension type insulators give more flexibility to the line and mechanical stresses due to the wind and other factors are reduced in this suspension type insulator arrangement. The connection at the cross arm is such a way that the insulator string is free to swing in any direction and thus takes up a position where it experiences only a pure tensile stress.
- The suspension type insulators, when used in conjunction with steel supporting structure, has the advantage of rendering the conductorless liable to the affected by cross-arm thus enabling the tower to function as the lightning rod.
- In case of a rapid increase in the load on the transmission line, the increasing demand can be met by raising the line voltage than to provide another set of conductors. With suspension type insulators additional line insulation requirement can be obtained by simply adding one or more discs to the string.
- In case of long spans (river or valley crossings) where heavy conductor load is to be sustained, two-disc insulators can be yoked. Such an arrangement is not possible in pin type insulators.
- The only disadvantage of suspension type insulators is that large spacing between the conductors is required than with the pin type insulators due to the large amplitude of the swing of the conductors.