Study On Breakdown Experimental Device And Breakdown Performance Of Liquid Dielectrics Under Short-Pulsed Conditions

Pulse power with fast rise time technology was applied in many fields such as nuclear physics,electron beam,accelerator,laser,HPM etc. Insulating liquids are largely used in the generation, variation and transmission of UWP HPM. In high-power system, the dielectric insulating property is an important influencing factor .The study of the insulation breakdown property under the nanosecond pulse is important to the design of the compact pulse power equipment. But, now there aren't enough experimental findings for the study of short-pulsed dielectric breakdown in liquid to establish related theoretical frame, and there isn't accepted formula to calculate the breakdown voltages of liquid dielectrics. Therefore, in order to investigate the short-pulsed dielectric breakdown characteristic in liquid, based on the SM-3NS pulse source with the output voltage of about 200kV and the repetitive frequency by 2kHz, this paper focuses on the following:(1) The effects of the radius of hemisphere electrode on breakdown voltage of transformer oil;(2) The breakdown performance of three typical liquid dielectrics (transformer oil, dodecylbenz, castor oil) under DC, single pulse and repetitive burst conditions;(3) The breakdown characteristic of castor oil for different electrode gaps;(4) The effects of pulse duration on the breakdown strength of transformer oil;Based on the test result, this paper proposed that:(1) Design the breakdown experimental device and measurement system that meet the experimental demand, and analyze the electrostatic field of electrode model as well as estimated formula of the peak field strength;(2) With increase of the radius of hemisphere electrode, the breakdown voltages are continuously increased, but the action minish slowly;(3) Under short-pulsed conditions, the electric breakdown fields of transformer oil, dodecylbenz, and castor oil are far larger than in the DC regime, the detailed case is that the breakdown strength of castor is higher than that of transformer oil, and that of dodecylbenz is minimum, however, contrary to that for DC. The breakdown fields vary obviously with frequency in the low repetitive frequency range (<100Hz), but the relation curve become rather smooth from 100Hz to 2KHz. As compare with single pulse breakdown fields, the threshold field value is reduced in evidence;...