High-voltage cables are indispensable in X-ray machines. Are you familiar with the structure of high-voltage cables? Today we will briefly talk about the role of the semiconductor layer in high-voltage cables.
The semiconductor layer in the high-voltage cable is what we often call “shielding”, which is essentially a measure to improve the distribution of the electric field. The cable conductor is formed by twisting multiple wires, and it is easy to form an air gap between it and the insulating layer. In addition, the surface of the conductor is not smooth, which will cause electric field concentration.
Therefore, it is necessary to add a shielding layer of semiconducting material on the surface of the conductor, which is equipotential with the shielded conductor and has good contact with the insulating layer, so as to avoid partial discharge between the conductor and the insulating layer. Shield.
There may also be a gap between the insulating surface and the sheath contact, which is the factor that causes partial discharge. Therefore, a shielding layer of semiconducting material is added on the surface of the insulating layer, which has good contact with the shielded insulating layer and is in good contact with the metal shielding layer. The jacket is equipotential to avoid partial discharge between the insulating layer and the jacket, and this layer is shielded as the outer shielding layer.
For extruded insulated cables without metal sheaths, in addition to the semi-conductive shielding layer, a metal shielding layer wrapped with copper tape or copper wire should be added. The function of this metal shielding layer is to pass capacitive current during normal operation; when the system When a short circuit occurs, it acts as a channel for short-circuit current and also shields the electric field.
If this outer semiconducting layer and copper shielding are not present in the cable, the possibility of insulation breakdown between the cores of the three-core cable is very high. Therefore, when purchasing high-voltage cables, be sure to keep your eyes open and buy safe and qualified products.
Post time: Aug-10-2022