500 A Class Small AC Transformer Using Oxide Superconductor Operating at Liquid Nitrogen Temperature

Title, author, abstract

Possibility of Reduction in Hysteresis Loss Due to Reversible Fluxoid Motion in a Superconducting Bi-2223 Multifilamentary Wire
Edmund S. Otabe1, Yasuyuki Morizane1, Hiroshi Matsuoka1, Masayuki Izawa1
Teruo Matsushita1,2, Jun Fujikami3, Kazuya Ohmatsu3
1Department of Computer Science and Electronics, Kyushu Institute of Technology,
680--4 Kawazu, Iizuka 820-8502, Japan
2Graduate School of Information Science and Electrical Engineering, Kyushu University,
6--10--1 Hakozaki, Higashi-ku, Fukuoka 812--8581, Japan
3Basic High Technology Laboratories, Sumitomo Electric Industries, Ltd.,
1--1--3 Shimaya, Konohana-ku, Osaka 554--0024, Japan
A small superconducting transformer of 500~A class was designed and fabricated using a Bi-2223 tape for a compact AC current source for loss measurement. For the primary winding, a copper wire of 0.2~mm$\phi$ was wound on a bobbin of 54~mm in diameter by 300 turns. A silver-sheathed Bi-2223 multifilamentary tape with the critical current of 45~A at 77~K was used for the secondary winding. Ten tapes connected in parallel were wound by 2 turns to attain a sufficient secondary current. An iron core was used to get a good coupling between the primary and secondary windings. The peak secondary current reached 841~A at 35~Hz when the primary current was 9.28~A in liquid nitrogen. A distortion was not detected in the secondary current in the frequency range of 35--2000~Hz. The AC current energy loss density was measured for a Y-123 bulk superconductor prepared by QMG method using the transformer.
Original paper appears in
Advances in Superconductivity XI (Springer-Verlag, Tokyo), 1999