Contact Life Of 400V Class Low Voltage DC Switches

With the advent of the DC distribution market, securing the safety of the DC distribution system is emerging as a major issue. Like AC distribution systems, DC switches and circuit breakers are one of the main means to ensure safety. However, in the DC system, since there is no current zero point in the load current, the phenomenon occurring when the circuit is cut off is different from that of the AC system, so technical research is required to cope with this. In this study, the aging characteristics of the contact points of a 400V class low voltage DC (LVDC) switch are studied for the development of wall switches and circuit breakers for residential houses. As an arc extinguishing method to break DC load current, a prototype experimental circuit breaker that uses a magnetic extinguishing method that is effective for blocking low voltage low power DC is invented, and an automated experiment system is established. The DC switch under test repeats the operation of turning it on for about 1.5 seconds and then turning it off for 2 seconds until 10,000 times, and continuously evaluates the performance of the electrodes by calculating the voltage drop between the electrode contacts and the corresponding ohmic resistance value when conducting every 500 times.