Some factors affecting the diagnosis of latent fault in XLPE cable insulation

In this paper, some factors affecting the measurement of the characteristics of XLPE insulated cable are investigated. As many techniques have been developed for insulation assessment in the laboratory, it is important to understand some factors in hot-line measurement differing from those in the laboratory. Based on the purpose of using easily in hot-line condition, a model of a latent fault signal measurement system was constructed. In the experiment, the power voltage, the length of cable, and the resistance between metal shield of cable and ground are considered as important factors affecting measurement results. Through some investigations in laboratory, the influences of power voltage, length of cable, ground resistance on the fault signal are clearly shown. According to measurement results, some strategies for diagnosis and evaluation can be used to process the fault signals into standard values-and then the insulation state of cable can be predicted.