Measuring Energy Distribution of Surface Trap in Polymer Insulation by PEA Method

AC breakdown strength was studied in samples of low-density polyethylene(LDPE) and its composite doped with 3% ZnO nano-particles after UV irradiation for different time.Experimental result shows that the breakdown strength decreases in pure LDPE with the increasing irradiation time,while it is basically invariable in the composite.In addition,negative charges were injected to the aged side of specimen by corona discharge.Decaying property of negative charges was measured by pulsed electroacoustic(PEA) method after specimen was short-circuited directly.Then energy distribution of surface trap was obtained through formula derivation and calculation.The result shows that ZnO nano-particles can decrease deep trap density and increase shallow trap density in LDPE bulk through nucleation and increasing interfacial role,besides ZnO nano-particles improve the photo-stability of LDPE.