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Guidelines for the application of braced high voltage insulator assemblies are presented. Different types of braced insulator assemblies are described and the operating characteristics of each are given.

This paper provides an overview of the electric field (E-field) distribution on transmission line composite insulators applied in alternating current applications. Factors that affect the E-field distribution are discussed as well as the influence of the E-field distribution on the short and long term performance. Modeling and measurement methods are reported and examples of calculated E-field magnitudes determined are presented together with corona ring application information. This paper was developed by the IEEE Task force on electric fields and composite insulators.

Special measures may be needed to select line insulators for transmission and distribution lines in locations exposed to freezing conditions. This second part of the paper describes the strength of typical line insulation in these conditions and then deals with selection and mitigation methods based on the in-service stresses described in Part I.

Special measures may be needed to select line insulators for transmission and distribution lines in locations exposed to freezing conditions. This first part of the paper describes the environmental and electrical stresses encountered in service that influence the risk of flashover on line insulators. Part II of the paper describes the strength of typical line insulation in these conditions and deals with selection and mitigation methods.

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.

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.

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 Std.-4-1995 on standard techniques for high-voltage testing.

The use of nonceramic polymer insulators (NCIs) has grown, creating a very competitive market. In order to reduce the cycle time of design work and the cost of prototype testing, the use of electrical field stress analysis software can be applied. A commercially available software package is used to model insulators under a variety of applied voltages and contamination levels to establish relative electrical stresses. These stresses can be compared with designs that have been laboratory tested to verify an electrical performance improvement. The program was used to evaluate electrical stresses on insulators with different shed placements and profiles. Accelerated aging testing was conducted at EPRI (Electric Power Research Institute), and the data verifies the prediction of the computer model. Salt fog testing was conducted to determine the relationship between electrical performance and shed placement. The program was also used to evaluate electrical stresses on insulators with different corona ring designs. Testing was conducted in laboratories, and the data once again supports the predictions of the computer model.

Nonceramic distribution deadend insulators typically consist of a pultruded fiberglass resin core (FRP) with crimped or epoxy potted metal end fittings and a molded rubber housing. New technology has allowed for improved designs of distribution deadends, optimizing dry arc and leakage distances for constant section lengths. A patented fiber winding process, which is different from pultrusion and filament winding, has enabled new designs for lighter weight insulators. This paper discusses a distribution insulator design made with a new technique and the testing that was conducted to verify the integrity of the insulators.

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.