Search

In the present study, a novel solenoid type bifilar coil is proposed for high- T c superconducting fault current limiter (SFCL) which is composed of two windings in a bobbin and their winding directions are opposite with each other to have non-inductive characteristics. The two windings are connected in parallel at the current terminals for large current capacity. Besides, the current terminals are at the ends of the coil so that the electrical insulation design may be easier than that of other non-inductive coils. The novel solenoid type bifilar coil for SFCL is fabricated with BSCCO 2223 and tested in LN 2 bath at 77 K to investigate the current and voltage sharing as well as the current limiting effects. According to the test results, the current is limited effectively at first peak after the fault and the current sharing performance in each winding is verified under the normal and fault conditions. In order to compare with other bifilar coils, the AC losses are measured.

Recently, YBCO coated conductor (CC) called as second generation (2G) wire has been developed rapidly. The CC has a stabilizer layer for protecting the wire during a quench of the wire. In resistive superconducting fault current limier (SFCL), the stabilizer makes the resistance and limits the fault current during the fault. Therefore, specification of the stabilizer is one of important design factors in SFCL. This paper describes the current limiting characteristics of three coated conductors with respect to the specifications of the stabilizer. Two samples made by American Superconductors® have copper stabilizers attached by soldering. However, the two samples have not same structures. One has one-sided stabilizer, the other has both-sided stabilizer. On the other hand, another sample made by IGC-SuperPower® has copper stabilizer attached by electroplating, and the stabilizer layer surrounds the whole cross-section of the wire. Over-current tests of the three samples with various stabilizers were performed. Each sample has 8 cm in length. From the results, the SFCL using the CC wire could be designed.

With the successful commercialization of Bi-2223 powder-in-tube wire, various attempts in the R&D of the high- T c superconducting (HTS) magnets for high magnetic field applications are being implemented actively. Operating temperature of HTS magnet has to be maintained at the designed level but the magnetic energy and mechanical disturbance can cause unstable operational temperature of HTS magnet. Especially, the generated heat energy of inner HTS winding is apt to be accumulated, so the normal region appears in HTS winding. This paper deals with the quenching characteristics of three kinds of selected Bi-2223 wires: the high current density wire (HC-A) and the high strength wire (HS-A) made by AMSC and HTS wire (HW-I) made by Innost. The Innost wire has the highest minimum quench energy (MQE). The high current density wire has the highest normal zone propagation velocity (NZPV).

The 21st Century Frontier R&D Program was planned to develop and commercialize the inductive Superconducting Fault Current Limiter (SFCL) in Korea until 2011. The 1.2 kV/80 A inductive SFCL was planned to develop at the first year in the first phase (2001–2002) and the 6.6 kV/200 A inductive SFCL for short run operation test was planned to develop at the second and third year in the first phase (2002–2004). The experimental characteristics of conduction-cooled cooling system developed in the first year was very weak from the sudden large thermal disturbance. Therefore, the conduction-cooled cooling system was concluded not appropriate for the cryogenic technology of the application of superconducting fault current limiter. In the third year research, the improved sub-cooled nitrogen cooling system was adopted and investigated. In this paper, the characteristics of each cooling type was compared and the basic deign of ameliorated cooling system was introduced and the total heat load of the cooling system was calculated and compared with the heat load of the cooling system developed at 2nd year research.

The high- T c superconducting (HTS) magnet is an important element for developing HTS power equipments such as the dc reactor of the inductive type superconducting fault current limiter (SFCL). In order to use the HTS magnet for the large-scale power system, its critical current needs to be high enough. Generally, the double pancake HTS magnet has the severe decrease in the critical current because of magnetic field perpendicular to the tape surface. To fabricate a high critical current magnet, we wound a solenoid with the stacked tape. In this paper, the characteristics of the critical current of the HTS solenoid wound with the stacked tape were investigated. The results of this research can be used as the background data for the design of the large-scale HTS magnet.