The Siemens 5SM9345-0KK is a SENTRON RC unit electronic — a 4-pole residual current device (RCD) rated 63 A at 400 V AC, with a 30 mA trip threshold for type AC fault currents. The instantaneous design means it trips with no intentional delay, suited for direct shock protection or where fast disconnection is required. Rated current holds at 58.59 A up to 45 °C ambient; above that it derates stepwise to 50.4 A at 70 °C, so panel placement away from heat sources preserves the full 63 A rating.
Four-pole design occupies the full width of a standard modular DIN-rail enclosure. The 30 mA trip covers personnel protection in TN and TT systems; type AC detection handles sinusoidal AC residual currents only — not pulsed DC or smooth DC, so verify the downstream load profile before specifying.