Sachio Yasufuku

Electric Conduction Phenomena and Carrier Mobility Behavior in Dielectric Fluids

Electric conduction phenomena and carrier mobilitybehavior in mineral base electrical insulating oiland various kinds of synthetic base dielectric fluidshave been investigated in the low voltage region andhave been compared with our results in these fluidscontaining various kinds of oil-soluble impurities.It was shown that the impurities bring about someionic conduction in the fluids, and that the carriermobilities of the fluids containing the impuritiesnot necessarily seem to be governed by Waldens rule,depending on the types of the fluids and the impurities.In contrast, the fluids with industrial puritiesobey the rule. Furthermore, it was suggestedthat an electric conduction mechanism in the fluidscontaining the impurities seems to be closely relatedto a carrier mobility mechanism in these fluids.Thus, it appears advisable that the electricalbehavior of the artificial impurities dissolved in thedielectric fluids should be dealt with apart fromthat of the natural impurities.

Phenyl Methyl Silicone Fluid and Its Application to High-Voltage Stationary Apparatus

Phenyl methyl silicone fluids of low phenyl radical concentrations and low viscosities are characterized by their extraordinary gasabsorbing property in high electric fields. Their physical, chemical and electrical properties were investigated and compared with those of dimethyl silicone fluids. The corona resistant characteristics and applied voltage vs. life expectancy relationships were studied, using model capacitors consisting of the silicone fluid and polypropylene film capacitor paper insulation system, and heatresistant transformer models consisting of the silicone fluid and Nomex Aramid paper. It was found that the phenyl methyl silicone fluids greatly improve the corona resistance property and the life expectancy in high voltage fields over the dimethyl silicone fluids, although both fluids are similar in their general characteristics. As a result, it is suggested that the phenyl methyl silicone fluids can be used to construct reliable high voltage stationary apparatus which is small in size.

Electrokinetic Phenomena in Electrical Insulating Oil/Impregnated Cellulosic Pressboard Systems

A new method has been developed for measuring the zeta potential which exists on the surface of cellulosic pressboard impregnated with electrical insulating oil, while the oil streams through the capillary holes in the pressboard. The metal salts of di-(2-ethyl-hexyl) sulphosuccinate were dissolved in a purified insulating oil, and the zeta potential and the ac conductivity here investigated. The dependence of the zeta potential on the type and concentration of the salt was clarified. Electrokinetic phenomena in insulating oil are identical with those in aqueous solutions.

A Flash Point Behavior of Dimethyl Silicone Liquids

In order to understand why dimethyl silicone liquid of 50 centistokes, whose flash point is more than 300°C, undergoes ignition, the volatile products evolved during heating at 300°C in a controlled atmosphere were identified by GC-MS analysis. It was determined that a cyclic oligomer, D3 was dominant of the oligomers identified. The boiling point and flash point behavior of D3, D4, etc. were measured. From these results, it is suggested that D3 plays a decisive role in the igniting process. On the grounds that the decrease in evolution of volatile products would result in some improvement in the flash point behavior, a chelate compound of cerium was added to inhibit the decomposition of the silicone liquid. It was concluded that the flash point behavior can be improved somewhat by the addition of this compound, suggesting that the chain rearrangement reaction could be inhibited to evolve less of the cyclic oligomer, D3.

Maxwell-Wagner Dielectric Polarization in Polypropylene Film/Aromatic Dielectric Fluid System for High Voltage Capacitor Use

The chemical interaction between biaxially-oriented polypropylene film and diarylalkane has been investigated by studying the dielectric properties of the polypropylene film impregnated by the fluid. It was found that the ß dispersion in its dissipation factor-temperature relationship is related to the segmental motion of the amorphous phase existing in the film, and that the a dispersion is connected with the Maxwell-Wagner type dielectric polarization at the surface of the crystalline phase in the film. Furthermore, it was demonstrated that the dissipation factor at the ß dispersion temperature correlates well with the dissolution of the film into the fluid, and that the dissipation factor at the a dispersion temperature correlates closely with the oil absorption of the film immersed in the fluid.

Application of thermal analysis techniques to appraisal and quality control in Japan

This review deals with both inorganic- and organic-based electrical/electronic materials, including enameled wires, insulating varnishes, epoxy resins, thermoplastic resins, thermoplastic films, thermosetting resins, ferroelectric polymers, mineral-based transformer oils, zinc oxide varistors, rotating machine insulating systems, photoresists, glass-fiber-reinforced plastics, electronic ceramics, and high-T/sub c/ (critical temperature) oxide superconductors. The thermal analysis techniques considered are thermogravity, evolved gas analysis, differential thermal analysis, differential scanning calorimetry, thermomechanical analysis, thermally stimulated current measurement, and photoinduced calorimetry. An attempt is made to clarify how successfully a particular technique can be used for developing new materials or for evaluating a specific practical application of an electrical or electronic material.<<ETX>>

Radiation-Induced Degradation Phenomena in Electrical Insulating Oils

A mineral oil and a synthetic oil consisting of aromatic constituents were each irradiated by ¿rays at both room temper-ature ture and abo°t 70OC; the degree of the degradation was analyzed by means of gas chromatograms. The results showed that synthetic oil consisting of diarylalkane hydrocarbons has superior radiation-resistant properties. In addition, when mineral oil containing sulfur compounds was irradiated by ¿-rays in the presence of copper strips, the observed copper corrosion was slightly more rapid than that observed without irradiation.

Carbon-Fiber Technology and Its Application to the Electrical Industry in Japan

Compared to the United States and Western Europe, Japans carbon-fiber industry concentrates its efforts on marketing nonmilitary, industrial applications, such as electrical, automotive, sporting, mechanical, chemical, civil engineering,, and construction applications.

Electroconductive polymers and their applications in Japan

In this article, the research and development of electroconductive polymers in Japan are reviewed and the recent developments are described. Examples of the practical applications of electroconductive polymers in the electrical and electronic fields in Japan are mentioned and possible future applications are also suggested.

Calorimetric Measurements of Water Dissolved in Dielectric Fluids

In order to investigate how the water dissolved in dielectric fluids at room temprature behaves when subjected to cooling/heating, such dielectric fluids as alkyldiphenylethane and dimethyl silicone liquid in which various amounts of water were dissolved were investigated calorimetrically, using very precise Differential Scanning Calorimetry (DSC). Moreover, the degree of turbidity of the specimens which were cooled or heated at a constant rate in a low temperature bath, was observed visually to detect the appearance and disappearance of coagulation of dissolved water. As a result, it has been found that, whereas the water dissolved in alkyldiphenylethane appears to form an icy state, a coagulated state and a dissolved state at low temperatures, depending on its water contents, that on the other hand the water in dimethyl silicone liquid appears to form a coagulated state and a dissolvedstate, without any indication of formation ofice crystals. The author has succeeded in determining quantitatively the ice crystals produced from the water dissolved in a dielectric fluid at low temperatures using DSC. Thus, it has beenconcluded that this method has proved very useful for investigating the crystallization behavior of dissolved water existing in dielectric fluids at low temperatures.