Study On The Effects Of Magnetic Field And Eletrode On The Breakdown Of Glycerin

Compared with the commonly used storage media, glycerin dielectric has notable advantages such as high dielectric constant, great voltage endurance and notable resistivity. With the development trends of high power and miniaturization in the pulse power source, the glycerin has been a kind of potential energy storage media. But the study on the breakdown characteristics of glycerin dielectric is not enough to support the application of glycerin dielectric. This paper studies the effects of the magnetic field and the electrode surface features on breakdown characteristics of glycerin dielectric in the coaxial line. The main thesis work includes the following aspects:1. An experiment platform with about 20 ?s rising edge is built, and the voltage could be up to 500 k V. The priming method of glycerin and the exhaust means are prescribed. The voltage endurance of the glycerol dielectric in the coaxial electrode switch is texted preliminarily. The average breakdown field strength of the positive polarity is 216 k V/cm with 10.7 ?s charging time, and the average breakdown field strength of the negative polarity is 209 k V/cm with 10.6 ?s charging time. It implies that the glycerin dielectric has the same voltage endurance at the positive and negative polarity.2. The magnetic field time-space distribution in the air-cored transformer is studied. In the view of the complex environment of magnetic field in pulse power system, the magnetic field distribution is simulated and analyzed. It is found that the transformer with the coupling coefficient of 0.8 can generate a high magnetic field as the load voltage gets its peak. A high frequency response magnetic probe is made, with which the distribution of magnetic field in the transformer is measured, and the experimental results are in agreement with the simulation analysis.3. The breakdown characteristics of glycerin dielectric in the magnetic field immersion are studied. A kind of axial pulse approximate steady adjustable magnetic field of 0-1.0 T is established in the coaxial electrodes using the solenoid coils. The result shows that the steady magnetic field below 1.0 T can increase the breakdown threshold of glycerin with bubbles. And it can also increase the breakdown threshold of glycerin experiments at the first breakdown. But the magnetic field below 1.0 T can't increase the breakdown field strength in the pure glycerin. It means the magnetic field below 1.0 T is not enough to influence the breakdown in the liquid, but it can influence the breakdown of bubbles in the glycerin.4. The glycerin dielectric breakdown characteristics of four electrodes are studied. They are the sand paper burnished electrode, wool polished electrode, metal plated electrode and non-metallic plated electrode. Through the observation of the surface microstructure, the four kinds of electrodes' roughness, uniformity, and degree of vulnerable characteristics are contrasted and analyzed. It is proved that the several kinds of electrode surface morphology difference has certain relevance with glycerin dielectric breakdown characteristics through experiments. It can be concluded that the electrodes with less roughness can withstand higher voltage, at the same time has higher stability and effectively prevents the occurrence of low breakdown strength phenomenon at the first breakdown. By using of wool polished electrode, metal plated electrode and non-metallic plated electrode, the breakdown voltage increases by about 14.51%, 11.60% and 19.67%. Among these electrodes, the uniformity of nonmetallic plated electrode surface is far better than the others, and the breakdown field strength is up to 288 k V/cm with about 33.09% increasing than the control group.