Fault Characteristics And Mechanism Of Of High Voltage XLPE Cable Buffer Layer

Due to their excellent electrical and mechanical properties,good heat resistance and convenient installation and maintenance,the cross-linked polyethylene(XLPE)insulated cables have been widely used around the world.In recent years,a number of faults have occurred in the buffer layer of HV XLPE insulated corrugated aluminum sheathed cable at home and abroad.The fault location and fault characteristics are different from the previous HV cable faults,and the fault cause is still unclear.In order to avoid the recurrence of similar faults,it is of great scientific and engineering significance to study the fault mechanism of this type of XLPE cable buffer layer.Combining the experiment and simulation,this paper studies the fault characteristics,failure mechanism and influencing factors of the buffer layer of HV XLPE insulated corrugated aluminum sheathed cable.The main contents are as follows:1)Firstly,the XLPE cable buffer layer faults of 110 kV and above voltage levels at home and abroad were investigated to study the fault phenomenon.Secondly,the physical and chemical properties of the buffer layer material and the white powder deposited by the fault were studied.2)The white powder precipitation test of water blocking tape samples and short cable samples under different voltages,different pressures and moisture conditions(single or multiple factors)was carried out to explore the formation reasons of white powder and its influencing factors.3)The discharge ablation mechanism of buffer layer was analysed through simulation and experiment.Firstly,the effects of different air gaps,copper wire diameter and buffer layer properties on the electric field distribution of the cable were simulated.Secondly,the test was conducted to verify the simulation results.Finally,the formation process of buffer layer failure was discussed.The improvements of buffer layer faults such as improving the conductivity of the cable buffer layer and controlling the production process of the cable buffer layer are proposed.