Dependence of contact condition between strands on twist pitch in CIC conductor

We fabricated a model conductor using copper wire and measured the contact length by a pressure-sensitive paper, which changes color according with pressure. The contact length increased during the compression process of the model conductor due to strand displacement. The strand displacement and increase in contact length strongly depended on twist pitch in the sub-cable, strand tension in twisting process and compression method. Therefore, we fabricated four types of (3 × 3) conductors with different combinations of twist pitches in the first and second order sub-cables to investigate the relationship between twist pitch and contact length. Smaller twist pitch in the first order sub-cable is more effective in reducing contact length. Twist pitch in the second order sub-cable did not have a strong influence on the contact length. The strand displacement in the first order sub-cable was more closely related to the twist pitch in the first order sub-cable than that of the second order sub-cable. These results imply that the smaller twist pitch in the first order sub-cable could reduce irregular coupling loss with long time constant more effectively.