Diagnostic Method for Monitoring Core Position and Strand Failure in DC Superconducting Cable

We have developed a diagnostic method for monitoring core position and strand failure in DC superconducting cable. DC superconducting cable has been expected for various uses such as HVDC, railway feeding, etc. On the other hand, diagnostics is indispensable for its practical operation. In particular, knowing core position in cooling process is important because the position significantly influences the thermal invasion from outside. Furthermore, detecting strand failure is also crucial as a presage of a significant fault. This can be performed by measuring stray field distribution changed by such situations. An apparatus, which can be clamped on the outer (corrugated) pipe of the cable, was fabricated with an array of multiple Hall sensors. As a result, the position of the core was successfully estimated with the accuracy of 1 mm. Furthermore, one strand failure among 16 strands was also successfully detected. We believe that this method will be a promising technique for diagnostics for DC superconducting cables.