Through the study of the bulk phase structure system and the double-probe structure system, the electronic structure and conductivity of nano-magnesium oxide doped polyethylene are discussed. At present, high-molecular polymers are common insulating materials for high-voltage transmission cables, such as polyethylene and cross-linked ethylene, which are relatively common in use.
The way to improve the performance of composite materials can be added by adding inorganic materials, montmorillonite, nano-oxidized particles, etc. , when a certain proportion of additives are added to the composite material, the mechanical and electrical properties will be improved accordingly.
In 2006, the dielectric properties of LDPE/magnesia nanocomposites were studied. Under AC high voltage, in 2008, it was found that the space charge behavior of LDPE/magnesia nanocomposites containing magnesium oxide nanoparticles with different particle sizes, especially It is studied under the condition of high temperature and high power plant. The results show that, between 30°C and 60°C, in order to reduce the increase rate of the electric field, the number of nano-magnesium oxide particles is gradually increased, and this effect will be obtained. In addition, in order to reduce the distortion of the electric field and the injection of delocalized charges, corresponding research has been done on the particle size of nano-sized magnesium oxide particles, and it is found that nano-sized magnesium oxide particles are significantly better than micron-sized particles.
Magnesium oxide particles, when a small amount of nano-magnesia particles are used on the substrate, the effect is more obvious.
Adding nano-magnesia modified polyethylene with EVA assistance can significantly reduce the problem of space charge accumulation. While solving the accumulation problem, it is also found that this modification can also improve the mechanical properties. When the addition amount of nano magnesium oxide is 2wt%, better effect can be obtained.
At this time, the nano-magnesia/LDPE composite material can effectively reduce the accumulation of space charges, and the effect is significantly lower than that of insulating polyethylene alone. The results of the experiment show that the cathode charge density in the composite material is reduced to 2.5C/m3, and the anode charge The density is reduced to 3.5C/m3. In the direct current breakdown experiment, it was found that the breakdown field of LDPE doped with nano-magnesium oxide was stronger than that of undoped LDPE, and the maximum increase could reach 18.2%. In the AC voltage breakdown experiment, the same conclusion was obtained. In addition, the breakdown field strength varies with temperature, and when the temperature increases, the breakdown field strength decreases accordingly.