Prediction of Critical Currents in Superconducting Windings Using Wire Data and Field Modeling

Abstract

This paper reports on the integration of publicly available HTS conductor electromagnetic performance data into a magnetic Finite Element model for determining the critical current distribution along a section of conductor in a spatially fluctuating magnetic field. The simulation results from this model are shown to be in close agreement to experimentally obtained results. Typically monitoring for quench is done by measuring the volt-drop along a section of conductor to be protected and determining when the volt-drop reaches a predetermined level. This work shows that under spatially varying magnetic field conditions, small areas of the voltage monitored section of conductor could have already surpassed the critical current level for that section of conductor and hence stand a high probability of being a site for quench. Under these conditions, it is proposed to use the maximum electric field developed along the conductor as a criterion for determining the critical current. This work points to the need for developing a quench detection technique that can be applied to much smaller sections of conductor, particularly in geometries that are expected to experience the largest variations of magnetic field such as that in a rotating electric machine.