Detection of manufacturing defects in polymeric cable joint insulation using X-rays

Defects can be accidentally introduced into the insulation system of cable joints during manufacture, due to the manual nature of the jointing process. Any defect introduced can have an affect on the working lifetime of the cable, therefore, it is necessary to detect and remove these defects. Detection of defects can be achieved by using conventional X-ray techniques, however, there are problems with this method of joint inspection that are associated with the development, inspection and storage of the photographic film. These problems have been removed by the conversion to a digital CCD array X-ray camera. The digital images produced using the camera can be inspected for inclusions and voids using the changes in the pixel intensity distributions caused by such a defect. The result of this inspection is a binary image of the defects found. This image can then be superimposed back onto the original image in order to locate the defects found.