Scanning of screened plastic cores for discharges

Scanning plastic-insulated cores for discharges is now established as an intermediate test during the manufacture of plastic-insulated high-voltage cables. The paper opens with a brief survey of the existing methods, which are applicable to unscreened cores only; this is followed by a description of a new method for scanning cores provided with a semiconducting screen. Advantages and disadvantages of the various methods are discussed. The recording of discharges is an important factor common to all scanning methods. A device for recording the discharge sites as a function of their location is described.