Gas-insulated switchgear (GIS) has been widely applied since 1968 in Japan due to the compactness and high reliability, and has the brilliant history during this half century. This paper is the second report of GIS history following the first one which described the transition of technological development and practical application. The second report mainly deals with the wide spread and enlargement of GIS application from the middle of 1970s to the end of 1980s. First, progress of GIS construction such as three phase enclosed and combined GIS, and basic technologies which allowed these progress are mentioned. Secondly, downsized and improved performance of GIS equipment including GCB and MOSA are explained, and typical examples of GIS application which reflected these technical progress are introduced. Finally, the authors try to discuss the differences between domestic and overseas GIS technologies in terms of the downsizing process, and mention how these technologies and products in the second stage brought impacts on the next technologies and progress of GIS in 1990s.

Surge arrester with a spark gap has been installed for protecting electric power apparatus from lightning surge in Japanese distribution system. A high - stable discharge characteristic is desirable by shorting the discharge time lag for the spark gap. The top and the bottom face of a ceramic spacer for sustaining the spark gap in a surge arrester contact with electrodes, of which the electric field becomes high. In this study, we performed V-t tests by applying the impulse voltage of 20-42 kV with 1.2/50 µs and measured the number of electrons per unit time against some spark gaps which differed in relative dielectric constant of a ceramic spacer. The higher relative dielectric constant contributed on raising electric field and forming corona discharge at the bottom face of the ceramic spacer, which increased the number of electrons and shortened the discharge time lag.

With XLPE cable of 11 kV or less, dielectric breakdown is considered to occur during operation with a bridged water tree, and it is considered that with XLPE cable of 22 kV or more, dielectric breakdown occurs during operation with unbridged water tree. Various voltage characteristics of low frequency loss current of 6.6 kV XLPE cable with different degradation are measured this time. As a result, it was confirmed that the low frequency loss current of the thermal degradation cable conforms to the Ohm’s law, and the low frequency loss current of the water tree degradation cable shows a peculiar electric field dependency. Moreover, we could also confirm the difference in characteristics between the bridged water tree degradation cable and the unbridged water tree degradation cable.

VO_x thin films were fabricated on Si₃N₄/SiO₂/Si substrates by firing precursor films, which were fabricated by metal-organic decomposition (MOD), with a reduced pressure. Resistance-temperature (R-T) characteristics of the films indicating the phase transition from metal to insulator with about 4 orders of resistance change specified with VO₂(M) were obtained. Furthermore, the films fabricated with a firing temperature of 580 ∼ 600 ºC had temperature coefficient of resistance (TCR) of -2.8 ∼ -2.9 %/K at room temperature. After fabricating VO_x microbolometers with 40×10 µm² using the films on Si₃N₄/SiO₂/Si substrates, Si with a thickness of about 340 µm was etched using Deep-RIE and XeF₂ vapor etching from the backside of the substrate. Then, the VO_x microbolometer was completed on Si₃N₄/SiO₂ membrane. The VO_x microbolometer on Si₃N₄/SiO₂ membrane had a high DC sensitivity of 2310 W^-1, which was about 15 times higher than that of the microbolometer on the Si₃N₄/SiO₂/Si substrate.

The principle of sound production in human whistling is not well-known. A good understanding of the principle would be very beneficial to both the trainer and the trainee. The glottis opening area in human whistling is measured by using the endoscopic image data. This letter shows that the relationship between glottis opening area and frequency response in human whistling.

We have developed new high-resolution magnetic probe arrays using the advanced printed-circuit technology and high-density coil circuit design with field-component compensation. They are equipped with 5mm×3mm magnetic pick-up coils for r, z, θ magnetic field components. Each coil is composed of two-sided coil patterns with circuit line width of 0.05mm. This new probe technique enables us to measure detailed 2D profiles of X-point magnetic field whose special resolution is as high as 5mm: an important key for laboratory experiments of magnetic reconnection.