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In locations exposed to freezing conditions over the station service life, additional measures for selecting adequate station insulators at distribution and transmission voltage levels should be taken. This second part of the paper describes the selection process and mitigation options, based on the environmental parameters, as discussed in Part I. These include insulator size, shape, surface material, surface quality, electric field improvement, and orientation. [ABSTRACT FROM AUTHOR]

In selecting adequate insulators for substations at distribution and transmission voltage levels, special measures may be needed in locations exposed to freezing conditions. This first part of the paper describes the environmental and insulator parameters that influence the risk of flashover on station insulators exposed to freezing conditions. [ABSTRACT FROM AUTHOR]

A description of the composite insulator brittle fracture phenomenon suitable to allow correct diagnosis of a failure is provided. The paper reports on the number of brittle fractures that have occurred around the world and contains specific empirical data surrounding composite insulator brittle fractures in the United States. It also includes several case studies of in service failures to inform the reader of the diversity of initiating causes. The current state of knowledge on the brittle fracture mechanism is presented. Based on what was learned during the study, possible actions that can be taken by manufacturers and users to reduce frequency of occurrence are suggested. [ABSTRACT FROM PUBLISHER]