Irregular Loops With Long Time Constants in CIC Conductor
Irregular Loops With Long Time Constants in CIC Conductor
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DOI：
10.1109/tasc.2006.871277
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发表时间：
2006-06
影响因子：
1.8
通讯作者：
T. Yagai;H. Sato;M. Tsuda;T. Hamajima;Y. Nunoya;Y. Takahashi;K. Okuno
中科院分区：
文献类型：
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作者：
T. Yagai;H. Sato;M. Tsuda;T. Hamajima;Y. Nunoya;Y. Takahashi;K. Okuno
交流损耗包括与电缆绞合节距平方成正比的规则损耗和无法根据短导体样本测试结果估计的不规则损耗。从我们之前的工作中可以看出，由于 CIC 导体的空隙率低，绞线位置不对称而导致导体中不规则的环路，产生长达数百秒的长时间常数损耗。观察到的长时间常数表明，典型的环路长度应约为所有分段电缆节距的 LCM（最小公倍数），并且形成环路的两股线之间的接触条件应为线接触。为了详细研究接触情况，我们在长度为 1 m 的 CIC 样品导体上，每 11 mm 追踪 81（=3×3×3×3）股，其股线为 NbTi/Cu，无任何表面涂层。 81 根绞线的测量轨迹显示，绞线位置不对称，换句话说，由于压缩导体而导致绞线从其原始位置发生较大位移，从而提供了许多线接触。发现平均线接触长度达到约10 mm，比点接触长度10-2 mm大三个数量级
AC losses consist of both regular losses that are proportional to cable twisting pitch squared and irregular losses that could not be estimated from short conductor sample test results. It was explained from our previous works that irregular loops in conductor which are caused by asymmetric strand positions as a result of low void fraction of CIC conductor, produce the losses with long time constants up to several hundred seconds. The observed long time constant indicates that the typical loop length should be about LCM (Least Common Multiplier) of all sub-staged cable pitches, and that contact conditions between the two strands forming the loop should be line contact. In order to investigate the contact conditions in detail, we traced 81(=3times3times3times3) strands every 11 mm of CIC sample conductor with 1 m in length whose strands are NbTi/Cu without any surface coating. The measured traces of 81 strands show that asymmetric strand positions, in other words, large displacements of strands from their original positions due to compressing the conductor provide many line contacts. It is found that the averaged line contact length reaches about 10 mm that is three order of magnitude larger than the 10-2 mm of point contact length