Observation of Space Charge Formation in LDPE/MgO Nano-composite under DC Stress at High Temperature

Space charge formation in a nanocomposite thin film under dc stress at various temperatures was observed using the pulsed electro-acoustic (PEA) method. The LDPE/MgO nanocomposite materials, which is made of low-density polyethylene (LDPE) mixed with magnesium oxide (MgO) nano-size filler, has a higher resistivity under high dc stress than that in LDPE. Therefore, the material is expected to be used as an insulator of dc power transmission cable. To use the material as the dc power cable, however, it is necessary to study the space charge characteristics, especially at high temperature because an actual power cable is used at high temperature. Therefore, we tried to investigate the space charge formation in thin film of LDPE/MgO nanocomposite under dc electric field at various temperatures using PEA system. From the experimental results, it was found that the space charge formation was strongly affected by the MgO contents in LDPE/MgO nanocomposite.