Study of the space charge behavior in polyethylene nano-composites under temperature gradient

The temperature gradient, which occurs when HVDC cable is put into operation, can lead to space charge accumulation and distort the electrical field distribution in the insulation evidently. The addition of nano filler can dimish space charges in low density polyethylene (LDPE), therefore, the electrical strength of cable can be upgraded by replacing conventional insulation with nano composites. This paper aims to clarify the space charge behavior and insulation degradation under temperature gradient. Low density polyethylene (LDPE) and LDPE nanocomposite with 1 wt% (weight percent) nano filler were prepared. The space charge distribution under temperature gradient was measured via the Pulsed Electro-Acoustic (PEA) system, volume resistivity, DC breakdown strength, carrier mobility and the trap depths of samples were also investigated to further understand the behavior of space charge. As a result of the analysis of all the experiment results, it was concluded that the restriction of space charge accumulation caused by addition of nano filler is attributed to the fact that resistivity increases with temperature in LDPE nanocomposite.