The Salt Fog Test and its Use in Insulator Selection for Polluted Localities

After describing briefly the salt fog test, the authors show, by means of comparisons between laboratory results and results obtained in natural environments. that the behaviour of insulators in salt fog is very similar to their behaviour in representative types of natural conditions. Having thus established that the salt fog test is representative, the paper derives certain fundamental rules relating to the behaviour of insulators in salt fog as a function of their geometrical and surface characteristics. The importance of such rules is stressed in relation to the choice, on a quantitative basis, of insulators for areas with different degrees of pollution and suggestions are made as to the criteria and methods to adopt for classifying such areas.