In order to study the effect of volume resistivity of semi-conductive shielding materials on the space charge characteristics in HVDC cable insulation

conductive carbon black with different contents（represented by parts per hundreds of or resin） was added into ethylene-vinyl acetate copolymer（EVA） to prepare semi-conductive shielding materials with different volume resistivity. Using different resistivity shielding materials as electrodes

the space charge distribution in polyethylene was measured by the pulse electro-acoustic method. The results show that the volume resistivity of EVA composites decreases as the content of carbon black increases. When the content of carbon black reaches 32

the resistivity of composites will no longer decrease as the content of carbon black increases. The space charge density in polyethylene decreases first and then increases as the resistivity of the shielding material decreases. When the content of carbon black is 22

space charge in polyethylene is the minimum. When the content of carbon black is greater than 27

space charge in polyethylene increases rapidly.