Study On Dielectric Properties And Space Charge Properties Of EPDM-based Composites

High-voltage DC cable lines have the advantages of small loss,large transmission capacity,high operational stability,unlimited transmission distance,and the ability to connect to an asynchronous power grid,and their applications are increasingly valued.The high-voltage DC cable accessory is an important part of the DC cable line and is also the weakest part of the line.Under the action of the DC electric field,it is easy to generate space charge accumulation in the insulation,resulting in electric field distortion,and may even cause insulation breakdown,which to a certain extent limits the construction and development of high-voltage DC cable lines in China XLPE insulation.One of the measures to solve this problem is to develop and apply highperformance reinforced insulating materials and reduce the influence of space charge.In this dissertation,ethylene propylene diene monomer(EPDM)is used as the reinforced insulation material for high-voltage DC cable accessories,and chlorinated polyethylene(CPE)and maleic anhydride(MAH)containing polar groups are selected as fillers and prepared by blending.Different proportions of chlorinated polyethylene/ethylene propylene diene rubber based composites and maleic anhydride/ethylene propylene diene rubber based composites.The effects of doping type and doping content of fillers on the DC conductance characteristics,DC breakdown characteristics and space charge characteristics of EPDM composites were studied through experiments and attempts were made to explain.The experimental results show that the electrical conductivity of chlorinated polyethylene/ethylene propylene diene rubber based composites increases with the increase of chlorinated polyethylene content and is higher than that of pure EPDM;maleic anhydride The electrical conductivity of EPDM composites decreases first and then increases with the increase of maleic anhydride content;the DC breakdown electric field strength of chlorinated polyethylene/ethylene propylene diene rubber composites increases with the content of chlorinated polyethylene.With the increase of the content,the maleic anhydride/ethylene propylene diene rubber based composites,with the increase of the maleic anhydride content,the DC breakdown field strength of the maleic anhydride/ethylene propylene diene rubber composite first increased and then decreased;The amount of chlorinated polyethylene doping can effectively inhibit the space charge accumulation in the composite.When the mass fraction of chlorinated polyethylene is 0.5 phr,the inhibitory effect is best;the doping of maleic anhydride can improve the space charge of the composite material.Characteristics,when the content of maleic anhydride is 1phr,the inhibitory effect is most obvious.