The Dielectric And DBCD Characteristics Of New Polymer Nano-composite Film

With the development of power electronic technology and new semiconductor devices, more and more AC frequency conversion adjustable-speed motors have been widely used. However, the life of the motor is only about one or two years due to partial discharge, what is more, the insulations in some motors are broken-down during the test running. The progress in nano-science and technology provides new ideas and a way for developing new materials and modifying the present materials. The appearance of nanodielectrics opens a new application field of the electrical insulation. Generally speaking, the electrical, thermal and mechanical properties of nanodielectrics are better than those of conventional ones. With the wider application of nano-composite materials in the electrical fields, the research of dielectric properties of nano-composite materials has been the prerequisite of the application of these new materials. In recent years, a large amount of theory has been learned from the research of the dielectric properties and corona-resistant mechanism of the nano-composite films in our laboratory.As the background, the electrical strength, direct current volume resistivity, conduction current, dielectric spectrum, and corona-resistant time of the new polymer nano-composite film are measured and the data are obtained. The data will be the basis of the improvement of nano-insulating material. The corresponding experimental devices are made. Especially a set of the test equipment is designed, which makes the tungsten needle electrode using the ratio of the current change, and cutting off time is limited below millisecond. The radius of the tungsten needle electrode is made below micrometer and has lesser dispersibility. The effects of the test parameters on the results are analyzed such as the diameter of the tungsten filament, the aperture of the cathode and so on. It is proofed that the time of the preparation is short, the dispersion is small and the result is good.Finally, corona inception voltage, breakdown voltage, corona discharge graphics and current-voltage curves of nano-composite film inserting in needle-plane system are measured in the positive and negative polarity. Analysis and experimental results show that the new polymer nano-composite film can effectively increase the corona inception voltage and breakdown voltage.