Automatic centering of conductor in insulating covering - uses mean value of video signal generated on camera tube target with readjustment of radiation sources if necessary

摘要

Conductor position inside the covering is image by penetrating radiation on a camera tube target, and the image is scanned by an electron beam. Its deviation from the central position causes an asymmetry of the video signal from which an evaluation device derives control pulses used for centring the conductor in the covering. A mean value of video signal amplitudes is formed, and when it deviates from a nominal value, intensity of radiation sources is so readjusted, that the mean value returns to the nominal value.