3. Classification

In accordance with NF EN 60383-1, overhead line insulators are divided into two classes according to their shape.

• Class A

  It includes all insulators or string elements for which the shortest length ε of the perforation channel through the solid insulating material is at least equal to half the shortest distance in air $\mathfrak{L}$ outside the insulator. This shape implies that these insulators are imperforable.

  Example

  Long-barrel insulators generally belong to this class.

• Class B

  It includes all insulators or string elements for which the shortest...