Effect of Mechanical Pressure on Interface Charges of Double-Layer Cross-Linked Polyethylene

Space charges exist at the interface between high voltage direct current (HVDC) cables and factory joints, both made of cross-linked polyethylene (XLPE). The interface condition is closely related to the mechanical stress during the manufacture process of factory joints. In this paper, the space charge distributions in double-layer XLPE samples made at different pressures were measured using the pulsed electro-acoustic (PEA) method. Subsequently, the electric field distortions caused by these interface charges are analyzed. Experimental results indicate that increasing the pressure applied to the double-layer sample can reduce the accumulation of interface charges and mitigate the associated electric field distortion. Furthermore, the transport mechanism of interface charges under different pressure conditions is elucidated. This paper provides valauble guidance for the design and application of factory joints in HVDC systems.