Properties of insulators

       To provide necessary insulation, the insulators must have the following properties,
1. The insulators along with providing the insulation, also provide support to the conductors. Hence to withstand the conductor load alongwith wind pressure etc, the insulators must be mechanically very strong.
2. The main function of the insulators is to resist any leakage current. Thus the insulators must have very high insulation resistance.
3. The insulators must be free from internal impurities such as holes, cracks, laminations etc. this reduces the permittivity of the insulators.
4. The dielectric strength of the insulators must be very high.
5. To have high dielectric strength, the relative permittivity of the insulating material should be very high.
6. The insulating material should be nonporous.
7. The insulators should not be affected by the changes in the temperature.
8. Due to very high voltage of line conductors, there is possibility of flash over between line conductors and earth. The flash over means production of arc due to which extreme heat gets produces. This is the main cause of insulator failure. Hence the insulators must have high ratio of puncture strength to flash over voltage.


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