Distribution stability of additive concentration in insulation for EHV XLPE cables

In the interfacial diffusion method, an additive is mixed into the semiconducting layer and then diffused into the insulation during the cross-linking high-temperature process. In order to investigate the stability of additive concentration, model cross-linked polyethylene (XLPE) cables were prepared and aged by heating. The additive concentration distribution was measured by micro-beam infrared spectrometry. From the temporal change of distribution, the diffusion coefficient, the activation energy, etc. were analyzed. It was found that the additive concentration profile in the insulation is formed under the influence of the additive concentration distribution. The stability of the additive concentration distribution was estimated after long-term utilization because of the existence of a high molecular weight part which had a small diffusion coefficient in the additive