Research on on-line measurement of high woltage cables

When X-ray penetrating a kind of material, its energy loss is related to composition of the material and its thickness. According to the property, a measuring system is designed, which can measure on-line every envelope of high voltage cable. The scanner reciprocates in the perpendicular direction to the cable axis. It is connected with closed loop controlled electric motor, so as to get a stable velocity. When X-ray penetrating material, the surplus energy is a negative index function of thickness and material's other parameters. If number of materials is fixed, the negative index curve is smooth. Otherwise, there will be a salient point. By digital process, a series of kinks are found. Points of tangency of X-ray and envelope are found. When we know pulse number of two point of tangency as well as the velocity of the scanner, we can know the distance between two points of tangency. Certainly, thickness of every envelope can be obtained.