An Electromagnetic Processing of Materials (EPM) applies various electromagnetic phenomena to materials processing. An EPM is mainly applied to steel-making processes like heating, melting, stirring, flow control and so on. However, its application has been extended recently to nonferrous metals like aluminum, and even to nonmagnetic materials by the use of DC superconducting magnets. In the present paper, examples of EPM are shown and the applicability of superconducting magnets to conventional EPM is investigated. If AC superconducting magnets are applied to conventional EPM, the limit of EPM due to the weakness of the magnetic field will be broken and a new stage of EPM applications will be opened.

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Sodium-Sulfur battery (NAS battery), which has more than 3 times of energy density compared with the conventional lead-acid battery and can be compactly established, has a great installation effects as a distributed energy storage system in the urban area which consumes big electric power. For the power company, NAS battery contributes to the load leveling, the supply capability up at the peak period, the efficient operation of the electric power equipment and the reduction of the capital expenditure. And for the customer, it is possible to enjoy the reduction of the electricity charges by utilizing nighttime electric power and the securing of a security. The contribution to the highly sophisticated information society where the higher electric power quality is desired, mainly office buildings and factories by the progress of IT, is very big. Tokyo Electric Power Company (TEPCO) developed the elementary technology of NAS battery from 1984 and ended the development of practical battery which has long-term durability and the safety and the performance verification of the megawatt scale. Finally TEPCO accomplished the practical application and commercialization of the stationary energy storage technology by NAS battery. In this paper, we introduces about conquered problems until practical application and commercialization.

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We have proposed the voltage-current sensor embedded in a ceramic insulator for the real-time observation of the power factor in three-phase power distribution systems and carried out the finite element analysis to investigate its characteristics and verify its feasibility. However, the ceramic sensor has problems in cost and a burning process in manufacturing to result in the deformation from the designed form. In the paper, we propose a resin molded type of voltage-current sensor with dual search coils for the current sensor part based on the finite element analysis and discuss its steady state electromagnetic behaviors theoretically and experimentally.

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In Kyushu Electric Power's 6.6kV distribution system, after a single-phase ground fault occurred in the circuit of a distribution line, we experienced a phenomenon in which the analogue ground directional relays of the other circuits linked to the same bank were simultaneously tripped. In this paper, focus is placed on the mechanism and possibility of simultaneous tripping of ground directional relays. This mechanism was examined in an experiment carried out using an analogue simulator. The results of the test revealed that such simultaneous tripping was attributable to the neutral instability phenomenon of grounding potential transformers installed in an isolated neutral system.

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In transport section, it is necessary to reduce amount of CO₂ emissions and Oil dependence. Bio fuels and Fuel Cell Vehicle (FCV), Electric Vehicle (EV) and Plug-in Hybrid Electric Vehicle (PHEV) are expected to reduce CO₂ emissions and Oil dependence. We focus on PHEV. PHEV can reduce total energy Consumptions because of its high efficiency and can run with both oil and electricity. Introduction of PHEV reduces oil consumptions, however it also increases electricity demands. Therefore we must evaluate PHEV's CO₂ reduction potential, not only in transport section but also in power grid section. To take into account of the distribution of the daily travel distance is also very important. All energy charged in the PHEV's battery cannot always be used. That influences the evaluation.
We formulate the total model that combines passenger car model and power utility grid model, and we also consider the distribution of the daily travel distance. With this model, we show the battery cost per kWh at which PHEV begins to be introduced and oil dependence in passenger car section is to be reduced to 80%. We also show PHEV's CO₂ reduction potentials and effects on the power supply system.

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Pole-mounted transformer is one of the equipment that is easier to receive lightning damage. As our information society advances, the needs for supply reliability of electric power become higher, and the decreasing of lightning damages of pole-mounted transformers becomes necessary. In recent years, lightning protective devices (surge arresters) have been installed around the primary bushing of the transformers. Therefore, the number of disconnections around the primary bushing caused by lightning has been decreasing. However, the surge arrester that installed at the primary side of transformer cannot protect the transformer against backflow lightning that invades to the secondary side of transformer. The characteristic of the transformer damage by the backflow lightning is that electro-magnetic force occurring by the current flowing into the secondary side of transformer deforms the windings of the transformer. In this paper, the mechanism of transformer damage by the current flowing into the secondary side is clarified by the comparison between actual lightning damage case and the results of verification test using short-circuit generator. Effective counter measures against the damage of transformer by the backflow lightning are examined by EMTP calculations. From the calculation results, neutral grounding on low-voltage distribution line is the most effective measures in the point of decreasing of the amount of current flowing into the transformer. The less the grounding resistance, the less the amount of current flowing into the transformer. Moreover, decreasing the voltage of the secondary-side of the transformer is important to protect the bushing of the secondary-side. By the calculation result, it is clarified that the surge arresters installed around the secondary side of the transformer are effective for decreasing the voltage of the secondary side of the transformer.

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Wind power generation using an unlimited, natural energy is getting an attention regarding environment issues in recent years, and the installed capacity of wind power generation system is increasing at a rapid pace, resulting in deterioration of power quality especially in frequency and voltage. This fact will be a big problem to restrict large capacity of wind farm.
This paper proposes a new frequency converter: rotary frequency converter (RFC) to moderate the electric output from wind generation, which is to be installed between a set of wind generators and a grid, providing a smoothed electric output, promoting the wind power generation introduction. This mainly consists of a synchronous machine and the adjustable-speed machine. Independent controls of input/output voltage, active power, and reactive power offer electrical separation between the two networks. Experimental study of prototype model and its characteristics, especially dynamic control is discussed in this paper.

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In the ITER Engineering Design Activity (EDA), four Nb₃Sn model coils were developed and successfully tested. However, it was revealed that the critical current of the conductor degraded with the increase of electromagnetic force. One of the explanations of this phenomenon is a strand bending caused by enormous electromagnetic force. The authors therefore developed a simulation code using the distributed circuit model to investigate dependency of the critical current performance on the periodic bending deformation. The simulation results were in good agreement with the experiments. The dependence of the critical current on the periodic transverse load, temperature, periodic load pitch, thickness of Ta barrier which prevents Cu stabilizer to be contaminated by Sn, twist pitch of the strand and RRR of the bronze matrix was investigated using the developed code. The results showed that the critical current degraded less with decreasing the pitch of the transverse load and increasing the Ta barrier thickness. It suggests that the shorter cabling pitch and the larger bending stiffness prevent the critical current degradation.

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There are three main failure modes of ZnO varistors; thermal runaway, puncture and cracking. It is important from the operational point of view for user of ZnO surge arresters to know the fundamental mechanisms of these failure modes. I led many equations on these failures and simulated failure modes. I have been experienced the only failures of cracking which were occurred by lightning strokes operating our power systems. As the result of simulations, I found that this cracking results from that the highest thermal tensile stress is over the tensile strength and the relative expansion becomes longest too when the maximum temperature is shifted and the hole or the melt is occurred by the large lightning stroke current on the ZnO varistor.

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In practice, sometimes long grounding wires are applied to decrease the grounding resistance but the lightning performance of the grounding system is still poor because the grounding wires have an effective length. This paper presents an analysis of effective length for horizontal/vertical grounding wires using the minimize per-unit length impulse impedance method. The grounding response due to lightning current was simulated by solving Telegrapher's equations with the finite-difference time-domain (FDTD) technique. During the simulation, the voltage distribution was low enough to limit the electric field intensity not exceeding the critical value for soil ionization, E_c. The results of the simulation were proved with scaling experiments. The simulation analysis showed that the effective length of the horizontal/vertical grounding wires decreases with front time of impulse current. For example, in soil resistivity of 50Ω.m, the effective lengths of the vertical grounding wire are 29m and 5.3m for impulse currents of 10/350μs and 0.25/100μs, respectively.

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The performance of ZnO elements such as voltage-current characteristic, life performance under a continuous system voltage, energy absorption capability is strongly dependent on the performance of boundaries between ZnO grains formed during the sintering process. The performance of these boundaries is greatly influenced by spinel particles (Zn₇Sb₂O₁₂) that are produced between ZnO grains and hence have a relation to the formation of boundaries.
The authors studied the influence of reducing spinel particles on the performance of ZnO elements by experimentally manufacturing and evaluating the elements with various amounts of Sb₂O₃. As the result, some characteristics of the spinel-reduced elements were improved compared with that of normal ZnO elements: e.g. superior voltage-current characteristic, smaller micro-pores and larger capacitance. It was also found that the sintering temperature of the spinel-reduced elements could be decreased by more than 100°C than that of normal elements which the authors are currently manufacturing.

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Energy loss in transformer is composed of no load loss and load loss. No load loss of amorphous transformer (i.e. amorphous metal-based transformer) could be reduced by about 70% compared with traditional transformers (e.g. silicon steel-based transformer). If amorphous transformers are adopted to pole transformers owned by electric companies, large amount of energy savings and reduction of CO₂ could be realized. However, amorphous transformers have disadvantages of high initial cost and high load loss parameters compared with traditional transformers.
Economies of pole transformers are evaluated in the paper by the sum of the initial cost and the power loss cost, that is calculated by the load curve pattern of pole transformers. Authors propose a load curve pattern model for pole transformers and analyze the effects in cases which amorphous transformers are adopted to pole transformers.
Simulation results show that most of the losses in pole transformers are no load loss, and amorphous transformer is effective in achieving substantial energy savings as well as environmental benefits.

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This paper presents a construction method of loop distribution systems for the line loss minimization. The minimization of the line loss is realized by constructing the loop system to equalize both the ratios of R / L of all lines and the sending-end voltages of the distributing substations. The effectiveness of the proposed construction method has been verified by simulations.

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