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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TL;DR: In this article, the ac dielectric strengths of synthetic ester and natural ester in quasi-uniform electric field, using mineral oil as a benchmark, were investigated. And it was found that the 1-mm gap withstand voltages of esters are higher than that of mineral oil.
Abstract: As replacement of mineral oil, the application of ester liquids in large power transformers has become a hot topic in recent years. Understanding esters' dielectric behaviors under ac voltage is of vital importance for the insulation design of power transformers. This paper presents experimental studies on the ac dielectric strengths of synthetic ester and natural ester in quasi-uniform electric field, using mineral oil as a benchmark. The results show that esters have similar breakdown voltages to mineral oil when filtered and dehydrated. However, their breakdown voltages are significantly higher than mineral oil with the presence of particle and water contaminations. Furthermore, the breakdown voltages of esters are reduced more sharply than that of mineral oil with the increase of electrodes' Effective Stressed Area (ESA). Based on the experimental results, an estimation of the withstand voltages of transformer liquids in practical qualities was made when considering the particle effect, water effect and electrode area effect, and it was found that the 1-mm-gap withstand voltages of esters are higher than that of mineral oil.
60 citations
TL;DR: In this paper, a novel cooling method for the solar cells under concentrated solar flux is proposed where the surplus heat is removed from both the front and back surfaces of the module by directly immersing the cells in a dielectric liquid.
60 citations
Patent•
19 Dec 1975
TL;DR: By filling the container of a piezoelectric stack with a dielectric fluid under sufficient pressure, or applying sufficient pressure to a solid dieellectric, to maintain dieelessicle particle velocity and piezelessric particle velocity substantially spaced as mentioned in this paper, the failure of the piezelized stack is prevented.
Abstract: By filling the container of a piezoelectric stack with a dielectric fluid under sufficient pressure, or applying sufficient pressure to a solid dielectric, to maintain dielectric particle velocity and piezoelectric particle velocity substantially spaced, dielectric breakdown with consequent arc over and destruction of the piezoelectric stack is prevented.
59 citations
TL;DR: In this paper, the temperature in an electrical discharge machining (EDM) plasma was determined from measurements of relative intensities of the 411.85 and 413.29 nm Fe I spectral lines.
Abstract: The temperature in an electrical discharge machining (EDM) plasma was determined from measurements of relative intensities of the 411.85 and 413.29 nm Fe I spectral lines. The time-dependence of the plasma temperature was measured for individual electrical machining pulses. Under our experimental conditions (electrodes of C6(+) and M1E(-), cosmetic paraffin as the dielectric liquid) the measured plasma temperature ranged from 8000 to 10 000 K for different current pulses. We observed higher temperature values during the initial phase of the discharge. Temporal characteristics of discharge electric parameters, light emission and the plasma temperature are presented.
59 citations
TL;DR: In this paper, the authors described and evaluated acoustic waveguides for diagnostics of partial discharge (PD) in electrical insulation and dielectrics, and showed how the use of acoustic waveguide can improve diagnostic PD measurements in hostile and inaccessible locations.
Abstract: Acoustical waves travel by molecular interaction, and as a consequence, wave attenuation and transit time can be extremely sensitive to changes in the media in which they propagate. With careful acoustic measurements, a wide variety of media properties can be monitored. These range from variations in gas mixtures and pressure, to changes in material density, porosity, and crystal size and orientation. Acoustical technology can also be applied in the listening mode to sense the tiny acoustic emissions from partial discharges in dielectrics, and from stress, strain, and other events. Many of these acoustic techniques are ideal for applying to the science of electrical insulation and dielectrics, and in this paper these different methods are described and evaluated. The subject is introduced with an outline of ultrasonic partial discharge (PD) diagnostics and nondestructive evaluation, with emphasis on acoustic factors which affect accuracy. It is then shown how the use of acoustic waveguides can improve diagnostic PD measurements in hostile and inaccessible locations. In a completely different application, a technique is described in which sound velocity measurements in gas mixtures are used for predicting electrical strength. Other valuable acoustical applications which are outlined are the monitoring of sounds from bouncing particles on metal surfaces and from gas bubbles generated in liquid dielectrics. From this latter phenomenon the temperature of a hot metal surface in a liquid can be estimated. A related subject which is also discussed is the attenuation of sound waves by gas bubbles in a liquid dielectric.
59 citations