Abstract
Glycerin is a promising liquid dielectric for pulsed power systems because of its high storage energy density and high resistivity. In order to further improve the energy storage density of glycerin, its breakdown characteristics should be investigated. In this paper, experiments are carried out to study the decline of the breakdown voltage of glycerin in a repetitive pulsed pulse forming line (PFL) in both the single pulse mode and the repetitive pulsed mode. It is shown that the breakdown voltage of the glycerin PFL is reduced by about 35% after 100 pulses in 10 s. The bubbles in glycerin are suspected to be an important factor affecting the breakdown characteristics. By using a high-speed camera, the deformation of bubbles (especially the height) is observed in the experiments and the deformation of bubbles is cumulative after multiple pulses. Experiments confirm that the bubbles’ height is influenced by factors including the electric field, pressure, and temperature. These experimental results demonstrate an important process of the liquid breakdown in the repetitive pulsed mode, which will be helpful to improve the breakdown characteristics of liquid dielectrics.
Highlights
With the emerging applications of pulsed power technology in industry, high reliability, high repetition rate, and compact volume are required for the repetitive pulsed power generators.1–3 in the repetitive pulsed mode, the total energy and the average power of the system increase rapidly, meaning that more heat is generated and the probability of breakdown is increased exponentially.4,5 the insulation problems in the compact repetitive pulsed generators become more complicated and difficult to be solved.Liquid dielectrics are widely used as the energy storage medium because of their good insulation recovery, fast heat dispersion, and high energy storage
The results show that the bubbles play an important role in the breakdown process of the repetitive pulsed glycerin pulse forming line (PFL)
Before the breakdown happens in the glycerin PFL, the trigger switch St works to release the energy to the load RL
Summary
With the emerging applications of pulsed power technology in industry, high reliability, high repetition rate, and compact volume are required for the repetitive pulsed power generators. in the repetitive pulsed mode, the total energy and the average power of the system increase rapidly, meaning that more heat is generated and the probability of breakdown is increased exponentially. the insulation problems in the compact repetitive pulsed generators become more complicated and difficult to be solved. Liquid dielectrics are widely used as the energy storage medium because of their good insulation recovery, fast heat dispersion, and high energy storage. Their insulation problem is extensively concerned as well, such as the utilization of deionized water. Glycerin has a high dielectric constant (εr ≈ 40) and high resistivity (up to 1000 MΩ cm) It has preliminarily been applied in high power pulse transformers, pulse forming lines, and inductive voltage adders.. Similar to other energy storage dielectrics, the breakdown field strength of glycerin declines in the repetitive pulsed mode. The deformation of the bubbles in the glycerin PFL during the multiple pulses is observed and studied using a high-speed video camera.
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