Development of a Standard Model for Low-Voltage DC Switchgear Considering Electrical Safety

This paper proposes a standard model to enhance the safety and efficiency of low-voltage direct current (LVDC) switchgear. While alternating current (AC) systems are supported by standardized single-line diagrams in the Korea Electrical Code (KEC), DC systems still lack such models. To address this, AC standardized single-line diagrams and KEC regulations were analyzed to derive an LVDC standard model, supported by component-specific application criteria. Six types of LVDC single-line diagrams were additionally presented. A 50 kW testbed was built to validate the model through tests on load variation, rapid load change, voltage fluctuation, parallel operation, ground faults, short circuits, and overloads. Results confirmed that the proposed model ensured proper interruption and protection under all conditions. This study provides fundamental data for advancing LVDC commercialization and developing international standards.