Improvement of the Safety Verification Framework for Electric Vehicle DC Charging Facilities Considering Protection Function Verification

Ensuring the safety of electric vehicle DC charging facilities requires not only verification of the conditions of installed facilities but also consideration of the verification scope for DC output-side insulation monitoring and fault-response protective functions. This study compares the verification objects and objectives across three distinct layers: facility safety inspections based on the Korea Electro-technical Code (KEC) and the Korea Electrical Safety Code (KESC), product safety verification based on KC 61851-23, and the self-diagnostic functions embedded in the charging system itself. The analysis is limited to System C, which corresponds to the DC Combo (CCS) fast-charging interface used in Korea. The proposed 2026 amendment to KC 61851-23 is treated separately as comparative material for identifying the direction of future technical requirements rather than as a currently effective legal basis. The analysis shows that facility-side earthing and insulation inspections differ in both verification object and purpose from DC output-side protective-conductor continuity monitoring and insulation-monitoring functions on the DC output side. It also confirms that the charging system independently performs insulation verification before charging and continuous insulation monitoring during operation. The fundamental requirements for insulation monitoring and protective actions are already included in the currently effective KC 61851-23, while the main differences introduced by the proposed amendment lie in terminology and the level of detail in the associated test procedures rather than in the underlying assessment principle. Accordingly, this study proposes a staged safety verification framework consisting of product safety verification, installation and field safety confirmation, utilization of operational diagnostic information, and conditional verification of protective functions. Prior to institutionalization, available diagnostic information is used as supplementary information for maintenance and technical diagnosis, while detailed verification through fault-state reproduction is performed only when clearly defined conditions arise, such as recurring safety-related anomalies or the repair or replacement of major protective components. Incorporation into statutory inspections should be considered only after field validation and standardization and only when the KESC and related public notices are amended accordingly. Because resistance values and response times differ in meaning and applicable conditions across standards, this study does not propose a single new acceptance criterion.