An optimized BSCCO/Ag resonator coil for utility use

Abstract

Tlic prcsciit gciwratioii ol' BSCCO conductors is very promising for commci+cial npplicalioii i n ciicrgy distribution nctworks [I]. Tlicrcforc, rl dcmoiislratioii project was initinted lo dcvclop tlic tcchniqucs, iiccdcd I'm llic production of M V A class HTS cuils. Parallcl lo tlic rlcvclopincnl, the gnincri knowledge is tr;insferretl to relevant incinbcrs in h c indiistry, to reduce the gap between the laboratory and the inclustry iis Fast as possible.An inclustry produccd I MVA rcsmiator coil, operating at 50 Hz and 65 IC has hccri choscii as a i'inal goal. The coil will bc opcmtcd in a circuit :is slimvii iii Fig, I. In this way a capxitor C or a cablc like an overhead Iinc can hc tested at l'ull powcr using a rclalivcIy sinall poww supply.Ttic coil is to hc coiislruclcd Imn n numbcr or sub-coils to tiavc thc opporlunily to cxaminc difrcmnt produclion tcchniqucs and clillcicnl npcrating circumstnnccs. This papa' describcs tlic first nf thc scrics or iridustry-protluccd sub-coils lliat hnvc hccn h i l l aiid lcslcd and tlic pilot cui1 cxpcrimcrits thai havc lctl to thc ctirrcnl design. DESIGN ASPECTSA number of sinall dinmcter, strinll height, as wcll as full diamctcr, small licigiil rlcmoiistrntor coils haw bccn conslnictcd ai~tl fiii;ilyxctI, to evaluate theories i d to t'lcklc production problems tit iiii eitrly stlige [2j, [3]. An ovcrvicw of all the pre-production coils is given in Table I. Main cvalualioris that arc pcrhincd on thc piloi coils are:Mccha~iical integrity; i.e. no dcgradation of the critical cinwnt is a1 lowcd tluriiig i nsulati OH, winding, therrnal cycling niid opertition of the coils.Thclmnl inlcgrity; i.e. sull'icicnt cnoling lo avoid Ihermal runaway during DC and AC operation.Insulation stabitity; i.e. the coils must be able to bear tlic combinntion of IO0 A,,,,$ and 10 kV,,,,, at low temperatures.Rcduction of thc rntlinl ficld componcnts to impmvc the criticnl currcnt and lower the losses by shaping the magnetic field by inciins of Ikrro-magnctic C-cups around tlic coil ctlgcs (see Fig. 2) 121, [31. 'This also lcarls to a reduction of lhc stray L'icld nntl incimscs (Iic scli-inductancc or the coil. Thc stiluiion requires ii spccific optimization as ihc ctltly current loss in iroii ciiii aincel the g i n in the supercontluclor.The gain in crilical current that can be iichicvetl in this way is about 30%.Thc electric qitnlity factor Q = Lo/R of a typical copper coil, operating at room tetnpeuatiirc is aliout 20. The qiidity factor of n supercotirluctiog air core coil is limited to 250 by the dominant loss due to thc radiai ficld components at thc coil edges. The dominant loss will IIC aca~cditcrl to tbc axial ficld when the rarli;il €icM compouents n i t ~~~I u c c dby field shaping nnrl a quality factor of 1000 is expected [ 2 ] .

The scaling law for the strain dependence of the critical current density in Nb3Sn superconducting wires

“…Critical currents were measured at 10 µV m −1 or calculated at 10 µV m −1 from measurements performed at higher electric-field criteria using n-values measured in Durham (the error bars show the effect of these calculations on the normalized values). The legends show the spring material (or the CICC jacket material), the value of applied strain where the critical current is a maximum (ε M ) and the value of the critical current at this maximum (I CM ) [29,[53][54][55]92].…”

Influences of voltage–current characteristic difference on quench development in low-Tc and high-Tc superconducting devices (Review)

“…Thus, low n in HTS devices permits them stable operation at current even more than the ''critical'' one (determined by the certain electric field on a conductor) if other conditions of (9) (good enough cooling and low enough current density) are completed. With n rising, the situation becomes Theory, n=12 Bi2223 coil from [4] Bi2223 coil from [23] Bi2223 coil from [24] Bi2223 coil from [20] Bi2212 coil from [19] Bi2223 coil from [25] LDX L-coil [26], best and worst scenario [8] Coils sizes rise Total conductor length/ Cooling surface, m -1 Relative Thermal Quench Current Fig. 3.…”

Performance boundaries in Nb3Sn superconductors

“…This lack of predictability renders a thorough discussion of the various pinning theories outside the scope of this thesis. For an overview of pinning theory the reader is referred to an introduction by Dhallé [186] and the more extensive reviews of Blatter [12] and Brandt [187]. Here, the discussion on pinning mechanisms will be limited to an introduction of the main concepts.…”