Topic
Liquid dielectric
About: Liquid dielectric is a research topic. Over the lifetime, 3702 publications have been published within this topic receiving 45150 citations.
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03 Jun 2012TL;DR: In this paper, the authors highlight the limitations of scaling up such results to high energy density capacitors as well as demonstrate the effect of self-healing and its necessity in high energy-density, high-total-energy devices.
Abstract: Despite a great number of reports on high-energy density dielectric materials, very little attention is paid to determining realistic energy densities of larger scale devices made of these materials. These materials are typically evaluated with very short duration voltage withstand tests on very small sample areas, typically on the order of a few seconds and a few cm2. Conversely, full-scale devices require very long operational lifetimes on the order of years, and dielectric areas as large as several hundreds of m2. Practical components must also include additional material such as major insulation and packaging, resulting in volumetric efficiencies much less than 100%. Increases in total dielectric area, operating time, and packaging inefficiencies reduce practical energy densities by one to two orders of magnitude. Here we highlight the limitations of scaling up such results to high energy density capacitors as well as demonstrate the effect of self-healing and its necessity in high-energy-density, high-total-energy devices.
14 citations
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TL;DR: In this article, the conduction current which precedes the electrical breakdown of a liquid dielectric has been observed, and it has been shown that it is a sign of electrical breakdown.
Abstract: THE erratic nature of the conduction current which precedes the electrical breakdown of a liquid dielectric has been observed by several investigators1,2.
14 citations
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TL;DR: In this article, an explanation in terms of the change in the local stored energy is offered. But the experimental results support the proposed mechanism. But they do not consider the effect of the local energy on the breakdown strength of the dielectric liquid.
Abstract: It is well established that the breakdown strength of a dielectric liquid falls as the electrode area or the volume of liquid under stress increases. The usual explanation of this effect is statistical. In this paper, an explanation is offered in terms of the change in the local stored energy. The results of experiments in which the stored energy is changed while the electrode area and test volume are kept constant are presented. The experimental results support the proposed mechanism.
14 citations
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TL;DR: In this article, the energy and flow of the medium between two electrodes were analyzed, allowing the establishment of a relevant model, and the results indicated that for super-high-thickness machining, the pulse energy must be adequate to compensate for the energy consumed in the molybdenum wire and inter-electrode working liquid.
Abstract: High-speed wire electrical discharge machining (WEDM-HS) of materials of super-high thickness (more than 1000 mm) is a challenging problem. First, sufficient energy is required to maintain the inter-electrode normal discharge. Next, there must be adequate inter-electrode dielectric fluid. Third, in order to generate a smooth cut surface, it is necessary to suppress the vibration of the wire electrode to reduce vibration lines on the cutting surface. To better understand these challenges, the energy and the flow of the medium between two electrodes were analyzed, allowing the establishment of a relevant model. The results indicated that for super-high-thickness machining, the pulse energy must be adequate to compensate for the energy consumed in the molybdenum wire and inter-electrode working liquid. In addition, the running speed of the wire electrode should be improved to ensure that there is a sufficiently high flow rate of the dielectric fluid. The servo control mode of the existing machine tools and dielectric fluid were improved and then a process experiment was performed. The experimental results show that the process can be carried out efficiently and stably and the workpiece surface can be cut smoothly using the improved working liquid and servo control mode.
14 citations
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TL;DR: In this article, detailed ultrasonic reflection measurements in piezoelectric LiNbO3 are reported which are compared to the results of the theoretical analysis of the previous paper, part I.
Abstract: Detailed ultrasonic reflection measurements in piezoelectric LiNbO3 are reported which are compared to the results of the theoretical analysis of the previous paper, part I. Differences in mode coupling and behavior are illustrated in several calculated examples. The calculated numerical results are demonstrated in a full image format. It is shown how dielectric fluid loading influences the reflection behavior and how strong piezoelectric coupling can lead to unexpected dispersion in the fundamental symmetric mode. The data confirms in each case the predictions of an exact partial‐wave analysis of the problem, including the dielectric influence of the fluid. These phenomena play a role in the design and performance of piezoelectric sensing devices.
14 citations