scope:

This guide is mainly applicable to three-phase systems up to 525 kV (phase-to-phase). For higher voltages the possible non-linear performance of insulators is still under study.

This guide is applicable to outdoor ceramic and glass insulators, used in a.c. systems, of the following types :

- long-rod and traction line insulator ;

- cap and pin insulator ;

- pedestal type post and rigid pin insulator ;

- substation and line post insulator ;

- hollow insulator ;

- bushing.

This guide cannot directly be used for special types of insulators such as insulators with con- ductive glaze, or covered, during the manufacturing, with any insulating material, for surge arresters and also for longitudinal insulation for open circuit-breakers. This guide does not deal with radio interference voltage, television interference voltage and audible noise, the intensity of which may be increased on some polluted insulators.