Asymmetric cable short circuit monitor - has magnetic circuit of several circular etc. sheet metal magnetic screens, and reed contacts in screen air gaps

摘要

The monitoring converter has a digital output and a magnetic circuit surrounding the polyphase cable. The magnetic circuit consists of annular, or omega-shaped, concentric screens of magnetic sheet metal, forming a coaxial cylinder round the monitored cable along 2/3 to 3/4 of its periphery. In the air gap(s) between the screens, at different radial distance from the cable axis, is fitted a chain of parallel-connected reed contacts, surrounding with negligible spacing the cable. These contacts are coupled to a bipolar terminal for connection to an appropriate instrument.