In Korea, GENI(Green superconducting Electric power Network at the Icheon substation) project has been conducted since 2008. The objective of the GENI project is to install and operate a 22.9kV/50MVA High Temperature Superconducting (HTS) cable system and a 22.9kV/630A Superconducting Fault Current Limiter (SFCL) system in the Icheon substation located near Seoul. It is important to design specifications considering real power system conditions for a successful application of the HTS cable and SFCL system to a real grid. This paper proposes a design specification for the short circuit withstanding capability of the HTS cable to apply to Korean power distribution system, from the viewpoint of a protection system. The HTS cable system with the proposed specification has been operated in the Korean real grid of the Icheon substation since August, 2011.