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외부 교류자장이 Bi-2223테이프의 동저항 및 손실특성에 미치는 영향
류경우,최병주,Ryu, Kyung-Woo,Choi, Byoung-Ju 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.5
A Bi-2223 tape has been developed for power applications such as a fault current limiter, a power cable and a superconducting magnetic energy storage system. In such applications, the Bi-2223 tape carries time varying transport current and in addition experiences time varying external magnetic field. It is well known that the external magnetic field not only causes magnetization loss in the Bi-2223 tape, but also drastically increases transport loss due to a so-called 'dynamic resistance' We developed an evaluation setup, which can measure transport loss in external at magnetic fields. Using this equipment, we measured the dynamic resistances for various amplitudes and frequencies of an external at magnetic field perpendicular to the face in the tape. Simultaneously we investigated the effect of an external ac field on transport loss with different experimental conditions. This paper describes test results ana discussions on correlation between the dynamic resistance and the transport loss for the Bi-2223 tape.
류경우,마용호,Ryu, Kyung-Woo,Ma, Yong-Ho 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.4
AC loss of a superconducting conductor has a strong influence on the economic viability of a superconducting fault current limiter, which offers an attractive means to limit short circuit current in power systems. Therefore, the AC loss characteristics in several fault current limiting elements of a coil type have been investigated experimentally. The test result shows that AC losses measured in the fault current limiting elements depend on arrangement of a voltage lead. The AC loss of a bifilar coil is smallest among the fault current limiting elements of the coil type. The measured AC loss of the bifilar coil is much smaller than that calculated from Norris's elliptical model. However, the loss measured in a meander, which is frequently used in a resistive fault current limiter, agrees well to the theoretical one.
마용호,이주영,류경우,손송호,황시돌,Ma, Yong-Hu,Li, Zhu-Yong,Ryu, Kyung-Woo,Sohn, Song-Ho,Hwang, Si-Dol 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.7
The AC loss is an important issue in the design of the high temperature superconductor (HTS) power cables and fault current limiters. In these applications, a cylindrical HTS conductor is often used. In commercialization of these apparatuses, AC loss is a critical factor but not elucidated completely because of complexities in its measurement, e.g. non-uniform current distribution and phase difference between currents flowing in an individual HTS tape. We have prepared two cylindrical conductors composed of a Bi-2223 tape with different critical current density. In this paper, the AC loss characteristics of the conductors have been experimentally investigated and numerically analyzed. The result show that the measured losses for two conductors are not dependent on both arrangements and contact positions of a voltage lead. This implies that most of loss flux is only in the conductors. The loss for the Bi-2223 conductor with low critical current density is in good agreement with the calculated loss from Monoblock model, whereas the loss measured for the Bi-2223 conductor with high critical current density doesn't coincide with the loss calculated from the Monoblock model. The measured loss is also different from numerically calculated one based on the polygon model especially in low transport current.
경사 외부자장에 대한 600 kJ급 SMES용 HTS도체의 DC V-I 특성
이주영,마용호,류경우,최세용,김해종,Li, Zhu-Yong,Ma, Yong-Hu,Ryu, Kyung-Woo,Choi, Se-Yong,Kim, Hae-Jong 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.1
We are developing a small-sized high temperature superconducting magnetic energy storage (HTS-SMES) magnet with the nominal storage capacity of 600 kJ, which provides electric power with high quality to sensitive electric loads. Critical current and N-value of a high temperature superconductor with large current, which was selected for the development of the 600 kJ HTS-SMES magnet, were investigated in various oblique external magnetic fields. Based on the critical current and N-value measured for the short sample conductor, we discussed the DC V - I characteristic of a model coil fabricated with the same conductor of 500 m. The results show that the measured critical current and N-value of the conductor for parallel field are constant in external magnetic fields less than about 0.2 T. However, for oblique fields, its critical current and N -value abruptly decrease in all external magnetic fields. Moreover, the measured critical current of the model coil well agrees with the numerically calculated one based on the DC V - I characteristic measured for the short sample conductor. This suggest that losses and critical currents for an HTS-SMES magnet made up of a high temperature superconductor with anisotropic characteristic are predictable from the data of a short sample conductor.