Overhead lines: equipment - Insulators

Although insulators account for only a small percentage of the cost of an overhead line, they are an essential component. Their role is to connect the live conductors to the supports and ensure electrical insulation between these two constituent parts of the line.

For this reason, the choice of insulator type, acceptance tests and in-service monitoring must be carried out with the utmost care. Given the current state of knowledge, it cannot be said that a new insulator that has passed the various acceptance tests will have a service life equivalent to that of the line. The difficulty lies mainly in the fact that, to date, no acceptance test has been able to show that an insulator has definitely aged. However, attempts in this direction are being made within the framework of the International Electrotechnical Commission.

This article is part of a series on overhead line equipment:

• "Overhead lines: equipment. Support foundations";

• "Overhead lines: equipment. Accessories".