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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. Index Terms--Climate, contamination, flashover, fog, high voltage, ice, insulator coordination, snow, station insulators.

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. Index Terms--Climate, contamination, flashover, fog, high voltage, ice, insulator coordination, snow, station insulators.

Test methods for evaluating flashover voltage of ceramic and nonceramic insulators under ice, snow, and cold-fog conditions are recommended. The paper describes the procedure to be followed at various stages of an evaluation test including preparation of the test object, insulator precontamination, ice, snow, and cold-fog deposits as well as voltage applications and flashover voltage evaluation. Some relevant parameters for ice accretion, flashover voltage evaluation, artificial pollution, and power source requirements are taken tram IEC 60129, IEC 60507, and IEEE Std.-4-1995 on standard techniques for high-voltage testing. Index Terms--Contamination, flashover, fog, high voltage transmission, ice, insulator, snow, statistical interpretation, test methods.

Presents the results and analysis of surface resistance measurements performed on nonceramic insulators (NCI). Determination if the surface resistance measurement procedure can be formalized to ensure repeatable and reproducible results; Housing materials of the NCI evaluated; Finding that surface resistance is an indicator of NCI aging.

This paper addresses the problem of stress calculation and optimization in a FRP (Fibre-glass Reinforced Plastic) pultruded rod crimped into a metal end-fitting. This type of assembly is used mainly for suspension and line post insulators. We discuss herein some aspects that merit consideration in any given design approach. In many respects FRP pultruded materials are anisotropic. The anisotropy of their elastic constants influences the distribution of stresses while the anisotropy of their mechanical properties (ultimate strengths) limits their load carrying capacity. Finally, the anisotropy of their failure modes governs the progression and the spread of the damage. Each level of anisotropy will be discussed distinctly.Geometrical considerations are also necessary to arrive at an efficient design. Namely, we will consider the frictional interactions between the end-fitting inner wall and the rod, then we will present our approach in selecting the appropriate LID ratio (i.e., the ratio of the end-fitting length over the rod diameter), and finally we will discuss the influence of the compression profile, i.e., the permanent radial displacement imparted to the rod due to the action of the crimping force. [ABSTRACT FROM PUBLISHER]

This is a position paper prepared by the IEEE Task Force on Insulator Icing Test Methods. Test methods for evaluating flashover voltage of ceramic and nonceramic insulators under ice, snow, and cold-fog conditions are recommended. The paper describes the procedure to be followed at various stages of an evaluation test including preparation of the test object, insulator precontamination, ice, snow, and cold-fog deposits, as well as voltage applications and flashover voltage evaluation. Some relevant parameters for ice accretion, flashover voltage evaluation, artificial pollution, and power source requirements are taken from IEC 60129, IEC 60507, and IEEE Standard 4-1995 on standard techniques for high-voltage testing. [ABSTRACT FROM PUBLISHER]

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]