Abstract :
Medium voltage switchgear using both vacuum and SF6 interruption techniques has been available since the 1970s and both approaches now enjoy significant market share around the world. Some countries have specific preferences for a particular technology mainly due to historical factors where trends have been established as a result of the technical orientations of the major suppliers in each country. Reyrolle have for many years manufactured switchgear products using both vacuum and SF6 for interruption. It is recognised that the two approaches differ considerably in certain fundamental aspects, but that these differences do not necessarily imply superiority of one technique over the other. For this reason, it is necessary to explore the fundamental differences in detail and to ensure that the performance of a particular product is suited to its application. The benefits brought to medium voltage switchgear by vacuum and SF6 technologies are essentially similar, resulting in low maintenance equipment with superior cumulative fault-breaking capability. Internal fault qualification of all new designs provides a dramatic improvement in operational safety. Manufacturers have chosen, according to application area, what they believe constitutes the optimum technology, based on technical, commercial and industrial factors. Manufacturers skilled in both technologies have not hesitated to exploit the benefits of both, including placing them in combination where appropriate
