The Research Of The Charge Behavior And Electric Strength In MgO/LDPE Nanocomposite

The nanocomposite material is more and more concerned as it is excellent electrical property. The electrical property of the original material can be drastically improved by adding a few percent of nano-sized filler.The MgO/LDPE nanocomposite has been successfully applied in HVDC transmission system in Japan.In this thesis, two models which have been builted basing on a great deal of experiments were described in detail. The space charge restraining mechanism of nanocomposite was explained by the model, and the boundedness was also be pointed out. The unmodified and different modified materials were measured by the PEA including positive high-voltage and negative high-voltage. We found that wet process modified and MgO/LDPE nanocomposite that the content of MgO is 4phr have a preferable effect on restrain the space charge, the explain is that electron injection barrier may be was raised as the doped nanoparticles. But there are some problems including disperse uniformity and diameter of particles. We will as much as possible improved these problems. Finally, this thesis have conducted the DC breakdown experiments for each MgO/LDPE composite dielectric, it can be found that the shape parameters and characteristics of the breakdown field strength of MgO/LDPE composite dielectric which are wet process modified and MgO content 4phr are better than polyethylene, and have analysed the mechanism of enhancing the DC breakdown field strength after mixing nanometer particle using multi-core model. The effect of MgO/LDPE composite dielectric to restrain space charge is largely depend on the preparation method and mixed process of nanometer inorganic particle, such as the partical size, purity and dispersity may have an effect on restraining space charge.