Arc Safe Operation Area of Low Voltage DC System

In the existing AC power systems, the load current becomes zero by itself every half cycle, so the breaking arc generated when the switch is cut off or the plug is disengaged from the socket outlet is just a short-time sparking of less than 1/4 cycle on average. However, since the load current flows continuously in a DC power system, the breaking arc generated when the facility is shut off is continuously maintained and can be generated into plasma, so the risk of an arc accident is very high. In order to cope with problems caused by arcs, protection regulations must be established to ensure safety against breaking arcs. For this, the physical properties of arc generation and extinguishing must be studied. This paper explores the experimental characteristics of the breaking arc discharge phenomenon that occurs in the normal brass electrode, which is the main component of the residential contact type wall mount switch and socket-outlet & plug. This paper analyzes the characteristics of the breaking arc according to the supply voltage and the size of the load power, and presents arc safe operation area defined by the supply voltage and the load power levels in which non-expert users can safely use the wall-mount switches and socket-outlet & plug facilities made of conventional brass electrodes.