Sensors and non-conventional VT and CT for medium voltage switchgear

This paper describes the technical reasons for the application of nonconventional current and voltage transformers in medium voltage distribution switchgear and investigates the merits and present difficulties associated with the use of such devices. In the absence, as yet, of an internationally adopted term, the author refers to them simply as `sensors´ bearing in mind that the devices themselves are not really new, only the application for which they are discussed here. The prerequisites for effective use are examined, together with the obstacles which have to be overcome before wider market acceptance can be achieved