PURPOSE: To inspect a power cable while it is kept live and to prevent bad influence on an insulating layer by a method wherein the area irradiated with X-rays is decreased, the outer side than the insulating layer is irradiated and the X-rays are picked up.
CONSTITUTION: An X-ray image pickup device 4 such as an image intensifier, an X-ray vidicon or the like photodetects X-rays radiate from an X-ray tube 7 and performs an image pickup operation. a diaphragm 8 made of a metal (e.g. lead) which shuts off the X-rays is mounted on the X-ray tube 7, and the area irradiated with X-rays can be adjusted freely. In an inspection, the irradiation with X-rays is first started from the outer circumference of a power cable 1, the area irradiated with the X-rays is moved gradually to the central part of the cable 1 while the screen of an X-ray TV monitor is watched, and the state of the inside is observed. When the outermost layer of an insulating layer 2 is projected on the monitor, the advance into the inside is stopped, the X-ray tube 7 and the image pickup tube 4 are moved in the directions indicated by the arrows shown in the diagram and the inspection is performed. In addition, the X-ray tube 7 and the image pickup device 4 are moved in the longitudinal direction of the cable 1 and the inspection is performed.
NAMITA HIROYUKI
KAWAZOE KAZUO
