PRODUCTION METHODS AND QUALIFICATION OF HOLLOW CORE INSULATORS FOR UHV BUSHINGS

摘要

The demand for electrical power increased steadily in the past decades and this trend is not being expected to stop soon. This leads consequently to higher voltage levels in order to transmit power economically. Lines with 800 kV DC or 1000 kV AC, respectively, are already state of the art in large countries with long transmission distances like China or India. Currently an 1100kV DC project in China is in the concept stage [1]. Manufacturers of equipment have to face the challenges coming up with this development in the energy market. The present paper will discuss issues and solutions for the production of ultra high voltage bushings with composite insulators. Additional to the principal requirements for these products, several specific issues have to be taken into account if certain dimensions of the parts are exceeded. Beyond the general requirements for bushings and insulators coming from IEC or IEEE standards, it is essential to enhance the qualification procedure. This fact will be demonstrated discussing the so-called scarf joint of the housing which is necessary if parts become longer than 6 m. Although the scarf joint is a well established method for joining polymeric components, it is indispensable to regard the specific mechanical and electrical requirements in high voltage applications.