Comprehensive Evaluation of Insulating and Switching Media in MV Distribution and MV Motor Control

An evaluation of insulation and switching media in medium voltage (1-52 kV) applications is presented in this paper. Special attention is given to motor switching and to distribution of electricity. The various insulating and/or switching media like oil, epoxy resin, air, SF₆ and vacuum are discussed. The various arcing media in medium voltage grids have evolved to a mature situation nowadays, and the pro´s and con´s of the various media in different applications are presented. Key words are associated to the prevention of the various over voltages that might occur in industrial networks and their relation to the switching media. The basic phenomena, such as current chopping and restrikes are reviewed and the harm that overvoltages can cause either by amplitude or rising time to the equipment. Besides the overvoltage aspects, the operation & maintenance aspects related to different insulating and switching media are surveyed and discussed.