An investigation into the qualities of new and field aged cycloaliphatic epoxide insulation in the Republic of South Africa

[摘要] ENGLISH ABSTRACT:The application of cycloaliphatic epoxide (CE) insulation in the Republic of SouthAfrica is investigated within this thesis. There was a request from industry to evaluatethe product and indicate its suitability for application within the various geographicand climatic zones typical of the RSA.An extensive survey was conducted into the historic origins of the material, and theexperiences of international utilities applying the insulation medium in respect ofpolluted conditions. The properties of the Automatic Pressure Gelation (APG) CEinsulator manufacturing process are discussed with reference to the manufacture ofglass and porcelain insulation, and typical areas for concern are discussed withreference to insulators found to deviate from specification.Typical insulators were obtained from the manufacturers and utilities associated withthe product, and were subjected to electrical, material and visual examination tests.The electrical tests included AC wet and dry, lightning impulse, clean fog, salt fog,mould release resiliency and the IEC 1109 voltage test. The material tests included theidentification of the epoxide systems in use in the RSA, ultraviolet radiation agingsimulation, water hydrolysis and salt deposit density tests.The main findings are:• CE insulation is sensitive to marine pollution and continuous-wetting pollutiontypes.• The use of CE insulation is promoted in respect of inland and mediumindustrial pollution types.• Class B pin-type CE insulation is prone to partial discharge related failures.• Surface roughening on the insulator surfaces leads to reduced AC wetflashover voltages and increased pollution catch.Additionally:• A comprehensive aging hypothesis was developed detailing three independentaging stages/modes applying to CE insulation.• A hypothesis was developed for a new evaluation method for documentingchanges on insulator surfaces due to the action of aging mechanisms: TheSurface Area Index.

[发布机构] Stellenbosch University