AbstractHigh current and high voltage DC circuit breakers have already been used in the field of fusion technology, in the Joint European Torus (JET) (P. Dokopulos and K. Kriechbaum, DC Circuit Breaker Arrangement 73 kA, 24 kV for the Joint European Torus, Elektrotechnische Zeitschrift A, 1976; P.L. Mondino, The JET ohmic heating circuit, 9th Symposium on Engineering Problems of Fusion Research, Chicago, US, Vol. 1, October 1981, pp. 386–389) and JT60 (R. Shimada et al., JT 60 power supplies, Fus. Eng. Des. 5 (1987) 47–68; R. Shimada et al., Development of high current DC circuit breaker for large Tokamak device, Fusion Technol. 1 (1978) 401–406) Tokamaks, with pulsed currents up to 90 kA or more, but were not able to simultaneously carry steady state currents of 60 kA and to interrupt current under high voltage. Therefore, R&D on high current (60 kA) and high voltage (20 kV) switches, especially on DC circuit breakers, has been undertaken in order to ensure the protection of the superconducting coils of the ITER Tokamak (Y. Shimomura et al., ITER Overview, 17th IAEA Fusion Energy Conference, Yokohama, Japan, October 1998; M. Huguet, The Integrated Design of the ITER Magnets and Their Auxiliary Systems, 17th IAEA Fusion Energy Conference, Yokohama, Japan, October 1998) in case of a quench (Y. Shimomura et al., ITER Overview, 17th IAEA Fusion Energy Conference, Yokohama, Japan, October 1998). For this purpose, the coil magnetic energy (in the range of several GJ) is discharged in a large resistor connected in parallel with the DC circuit breaker. Most of the coil circuits operate at 60 kA maximum DC current. Nevertheless, the Central Solenoid (CS) coil (Y. Shimomura et al., ITER Overview, 17th IAEA Fusion Energy Conference, Yokohama, Japan, October 1998) of the ITER Tokamak was designed, till the middle of 1998, to be operated at 168 kA. The assessment of such a circuit breaker concept, using parallel operation of 60 kA rated mechanical switches, will be developed in this paper. This theoretical analysis assumes the use of pure mechanical switches connected in parallel without any use of semi-conductor devices.
高電流・高電圧直流遮断器は、既に核融合技術の分野において、欧州トーラス共同実験装置（JET）（P. Dokopulos and K. Kriechbaum, DC Circuit Breaker Arrangement 73 kA, 24 kV for the Joint European Torus, Elektrotechnische Zeitschrift A, 1976; P.L. Mondino, The JET ohmic heating circuit, 9th Symposium on Engineering Problems of Fusion Research, Chicago, US, Vol. 1, October 1981, pp. 386–389）およびJT60（R. Shimada et al., JT 60 power supplies, Fus. Eng. Des. 5 (1987) 47–68; R. Shimada et al., Development of high current DC circuit breaker for large Tokamak device, Fusion Technol. 1 (1978) 401–406）トカマクにおいて、最大90 kA以上のパルス電流で使用されてきたが、60 kAの定常電流を同時に通電しつつ、高電圧下で電流を遮断することはできなかった。そこで、ITERトカマクの超伝導コイルの保護を確保するために、高電流（60 kA）・高電圧（20 kV）スイッチ、特に直流遮断器に関する研究開発が着手された（Y. Shimomura et al., ITER Overview, 17th IAEA Fusion Energy Conference, Yokohama, Japan, October 1998; M. Huguet, The Integrated Design of the ITER Magnets and Their Auxiliary Systems, 17th IAEA Fusion Energy Conference, Yokohama, Japan, October 1998）。この目的のため、コイルの磁気エネルギー（数GJの範囲）は、直流遮断器に並列接続された大型抵抗器において放電される。ほとんどのコイル回路は、最大60 kAの直流電流で動作する。それにもかかわらず、ITERトカマクの中心ソレノイド（CS）コイルは、1998年半ばまでの設計では、168 kAで動作するよう設計されていた。本論文では、60 kA定格の機械式スイッチの並列動作を用いたこの遮断器コンセプトの評価について述べる。この理論解析は、半導体デバイスを一切使用せず、純機械式スイッチの並列接続を想定している。