Nominal Current Test Performance of 2 kA-Class High-Tc Superconducting Cable Conductors and Its Implications for Cooling Systems for Utility Cables

Abstract

The current carrying performance of 3-10 m long superconducting cable conductor models has been evaluated. A reduced energy loss compared to conventional cables can be obtained using high-Tc superconducting materials due to the limited resistive and ac hysteresis losses in some conductor configurations. The conductors are characterised under dc and ac conditions. The current and voltage is recorded during the tests in order to determine the impedances and the losses of the cable models. Using a phase-sensitive measurement with two lock-in amplifiers, small losses can be accurately measured at high currents. The critical currents of these conductors are in the range of 1-3 kA, and ac losses smaller than 1 W/m are measured at 2 kArms. AC currents with peak values exceeding the dc critical currents are applied. Increased losses, in excess of the expected magnitization losses are observed when individual layers in the cables saturate. The loss-contributions from other components of the cable system are discussed,and the implications for the cooling apparatus for superconducting utility cables are determined.