Buying Polymer insulation: Point of View of a Utility in a Regulated Market - (PPT)

摘要

In Mexico, the capacitive graded porcelain bushings used in high voltage equipment, power transformers and Circuit Breakers are considered the second weakest element because they have a 26% risk of failure. This consideration is based on the analysis of the failures that occurred from 1983 to 1998 in power equipment of 230 kV and 400 kV published by CFE. On the other hand, polymer (non-ceramic or synthetic) materials had been in use as insulators for over the last 30 years with a mature technology for overhead lines. In the case of substation equipment like surge arresters, circuit breakers, transformer bushings, and column insulators, the application of polymer materials started later. The advantages of using polymer materials in bushings can be: ease of manufacture, lighter weight and greater flexibility than porcelain, higher hydrophobicity, and lower effort for transportation and installation than their counterpart. A few silicone rubber bushings and current transformers (CTs) with silicone housing were installed in three 400 kV substations, however; an early failure occurred in one of the bushings in approximately 5 years after installation. This failure turned on the lights to carefully analyze the behavior of this equipment in polluted environments. A preliminary analysis showed that some special contamination issues, the lack of national and international standards, the difficulties of the Utility to buy this not common equipment, the design of the equipment for countries with average ambient temperatures lower than Mexico, and the deficiencies in the installation or lack of supplier information are the main factors that can influence the correct selection of the equipment. This problematic is discussed in the paper.