With a miniaturization of electrical devices, the gap between electrode becomes lower and lower. In order to optimize the insulation design, the understanding of breakdown phenomenon across micrometer-scale gap is essential. In this study, breakdown characteristics across micrometer-scale gap was investigated based on experiment and numerical simulation. The result shows that the breakdown voltage under positive voltage application is 1.5 times higher than the one under the negative voltage application. The polarity effect can be explained by the source of initial electrons. Under negative voltage application, the initial electrons are emitted from the cathode surface based on Fowler-Nordheim equation. On the other hand, under positive voltage application, the insulator plays an important role on breakdown voltage.
Effects of environmental factors on partial discharge inception voltage (PDIV) under inverter surge voltage was discussed with multiple regression analysis in this study. As the environmental factors, humidity, temperature, and pressure were taken into account. These factors can change in high-voltage motors used for actual vehicles. The PDIV under a surge voltage showed different changes from that under sinusoidal voltage due to variation of initial electron generation probability depending on environmental change. Our results revealed that humidity has a significant effect on the PDIV under surge voltage, and there are interactive effects between humidity and temperature, and humidity and pressure. We discussed the effect of humidity and these interactions in terms of the generation of initial electrons from the air and verified this by measuring the density of negative ions in the air.
Recently, ZnO film paid much attention, for many application such as transparent conductive film and photo devise. In order to use as transparent conductive film, ZnO films need be obtained at high growth rate. Fabrication of oxide films by electrochemical deposition from aqueous solutions is possible to fabrication at low temperature. And thickness and electric characteristics of ZnO film can be easily controlled by electrochemical parameters. Mentioned above, this electrochemical deposition is optimal technique for manufacturing technique for transparent conductive film. We will support that the adjustment of the alkaline electrolyte for ZnO film gives the rapidly growth of ZnO films at low temperature. In this investigation, the influence of the electrical and optical properties for ZnO films with the deposition temperature will be investigated. For optical and electrical results, the growth rate and the carrier concentration of ZnO films increase with an increase in the deposition temperature. And the optical bandgap energy is constant at about 3.37eV. Thus, the electric property and deposition rate of ZnO film will be controlled by the deposition temperature.
The rectangular copper wire is used in all kinds of electronic equipment, and they are required to reduce loss. Among the losses of rectangular copper wires, AC copper loss caused by skin effect and proximity effect is the dominant in the high frequency band. This paper describes the effect of reducing the AC copper loss of a rectangular copper wire using the magnetic path control technology.