Study On The Influence Of Semiconducting Materials On The Space Charge Accumulation Of XLPE

Cross-linked polyethylene(XLPE)insulated cables are currently widely used in power systems.With the increase in cable applications,more and more overhead lines are replaced by power cables.Therefore,whether the cable can run safely is the key to the stability of the power system.The study found that the generation of space charge will distort the local electric field,and the molecular structure of the polymer will be destroyed in this case,resulting in electrical branches,which eventually lead to insulation breakdown,which is an important cause of cable failure.In the cable accessories,different semi-conductive shielding layers have different charge injection and diffusing capabilities,which is also an important reason that directly affects how much charge is accumulated inside the insulating layer.At present,the semi-conductive materials widely used in cable bodies and accessories are ethylene-vinyl acetate copolymer(EVA),silicone rubber(SR)and EPDM(EPDM).In order to explore the differences in charge injection and grooming capabilities of different semiconducting materials,reflecting the electrical and insulating properties of different serniconducting materials as cable accessories,three semiconducting materials were used to cross-link polyethylene under a DC electric field in the laboratory(XLPE)The test of the effect of accumulated charge characteristics in slices.And use the results obtained by the slice test to further explain the cause of space charge accumulation at the stress cone of the cable attachmentFirst,directly purchase three common cable outer semiconducting shielding materials required for cable manufacturing from cable manufacturers,which are ethylene-vinyl acetate copolymer(EVA),silicone rubber(SR)and EPDM.After self-vulcanization and compression in the laboratory,three samples of semiconductive materials with the same resistivity but different base materials were obtained.Then the experiment of the influence of the samples of the semi-conductive material with the same resistivity but different base materials on the accumulated charge inside the cross-linked polyethylene slices was conducted.The experiment found that among the three semiconducting materials with the same resistivity,silicon rubber(SR)as the upper electrode accumulated the most charge,and EPDM and ethylene-vinyl acetate copolymer(EVA)were less.Before the start of the second part of this article,three kinds of silicone rubber(SR)semiconducting material samples with different resistivities were first vulcanized and pressed in the laboratory,and then silicone rubber(SR)with different resistivities but the same base material was used.The test of the effect of semi-conductive materials on the internal charge accumulation of cross-linked polyethylene slices.It was found that in the test of silicon rubber(SR)semi-conductivity with different resistivity as the upper electrode,the upper electrode material with large resistivity will cause cross-linked polyethylene(XLPE)Increased charge accumulation in the slice.In this two-part experiment,the two variables of different binders and different resistivities are subdivided,and comparative experiments are conducted.The study found that for semiconducting materials,different semiconducting binders and different resistivities It will have a corresponding effect on the injection,channeling and dissipation of electric charges.These factors have led to the difference in the amount of charge accumulation in the cross-linked polyethylene insulation of different parts in the actual operation of the power cable.This conclusion further verifies that in the space charge accumulation test of the cable body,the accumulated charge at the stress cone of the cable attachment is far There are more reasons than other parts of the cable.