Current margin of 275 KV class HTS power cable with joint against fault current

The current margin of a jointed model cable of the 275 kV class high-temperature superconductor (HTS) power cable was measured under fault condition. The cable-to-cable joint is necessary to connect long continuous sections of the power cable. At the joint the superconductor is prone to degradation due to an excessive temperature rise caused by the current passing through normal conducting zones of the joint. The jointed, and for the comparison the joint-less cables were subjected to a short-circuited fault current of 63 kA rms for 0.6 s. In the results, the allowable current margins were about the same for both model cables. The jointed cable degraded at the joint area from the result of the magneto-optical (MO) image. The numerical simulations were performed to clarify current distribution and temperature rise at the cable joint area. The temperature rise as a function of the joint gap was also calculated. The experimental and simulation results were showed in this paper.