Due to the weather changing, Polymer disc insulator will be breakdown by lightning, when the same time voltage is called breakdown voltage.

Why do choose the polymer materials for insulator?
Polymer is a material whose internal electric charges do not flow freely, and therefore make it very hard to conduct an electric current under the influence of an electric field.

What is breakdown voltage for polymer disc insulator?
A perfect polymer disc insulator does not exist, because a portion of the polymer suspension insulator could becoming electrically conductive if the voltage applied across it exceeds the breakdown voltage. This is known as breakdown voltage of a polymer disc insulator.

The materials of disc suspension insulators in common
Some materials such as glass, porcelain and polymer, which have high resistivity, are very good electrical insulators. A much larger class of materials, even though they may have lower bulk resistivity, are still good enough to insulate electrical wiring and cables. Examples include rubber-like polymer disc insulator. Such materials can serve as practical and safe insulators for low to moderate voltages.

Polymer disc insulator used in electrical equipment to support and separate electrical conductors without allowing current through themselves, also called composite suspension insulator.

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