AC Current Loss of a Meander-Shaped QMG Current Limiting Device



E. S._Otabe__________1), T. Endo1), T. Matsushita1);2), M. Morita3)
1)Kyushu Institute of Technology, 680-4 Kawazu, Iizuka 820-8502, Japan

2)Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan

3)Nippon Steel Corp., 20-1 Shintomi, Futtsu, 293-8511, Japan



  The AC current loss of a meander-shaped QMG current limiting device was measu*
 *red.  The

specimen was cut from a bulk QMG Y-123 superconductor and the cross section and*
 * the total

length were 1.5 mmx0.5 mm and 170 mm, respectively. The voltage at each straigh*
 *t section was

measured to confirm a homogeneity of the specimen. A bridge shaped specimen was*
 * also prepared

for comparison. The AC current was applied to the specimen by a superconducting*
 * transformer

in which a Bi-2223 tape is used for the secondary winding. The maximum peak cur*
 *rent was about

200 A.

  Although the frequency was changed in the range of 35~200 Hz, an obvious freq*
 *uency de-

pendence of the AC current loss was not observed.  Hence, the pinning loss is d*
 *ominant in the

observed AC current loss. The specimen seemed to be homogeneous and not to be d*
 *amaged during

a manufacturing process, since the voltages in the measured sections were nearl*
 *y the same and

the energy loss density coincided with the result on the bridge specimen. The e*
 *xperimental result

of the AC loss agreed well with Norris's formula for an elliptic cross section.


Dr. Edmund Soji Otabe

Department of Computer Science and Electronics

Kyushu Institute of Technology

680-4 Kawazu, Iizuka 820-8502, Japan



tel&fax: +81-948-29-7683

e-mail:otabe@cse.kyutech.ac.jp