The Siemens SENTRON 5SM1746-0 is a 4-pole residual current circuit breaker (RCCB), type AC, rated 63 A at 400 V AC with a 500 mA tripping residual current and a 10 kA short-circuit current rating. It mounts on a DIN rail (REG) and fits a 4-module width unit — standard for a 4P device in a distribution board.
What the ratings mean for fit
The 63 A rating holds at 40 °C and 45 °C; above that it derates linearly to 50.4 A at 70 °C. That derating curve (–) matters if the RCCB sits in a warm enclosure or next to heat-generating devices — at 50 °C you have 60.48 A headroom, not the full 63 A. The 500 mA residual-current sensitivity is for equipment protection or fire prevention, not personnel shock protection. Type AC means it detects sinusoidal AC fault currents only, suited for standard resistive and inductive loads without electronic front ends. The 10 kA SCCR (short-circuit current rating) at 400 V AC means the device can safely interrupt a fault up to 10 kA without welding contacts or rupturing the case. That is typical for a distribution board fed from a transformer with moderate fault capacity; if the prospective fault current exceeds 10 kA, a backup fuse or MCB is needed upstream. Wire range accepts 1.5 to 25 mm² solid or stranded, terminated under screw terminals with a tightening torque of 2.5 to 3 N·m. The 55 mm installation depth fits standard enclosure depths; mounting position is any orientation.
Deployment context
Snaps onto a DIN rail in a distribution board or sub-panel. IP20 when installed with conductors connected — suitable for dry indoor enclosures, not washdown or outdoor exposure. Overvoltage category III means it is rated for fixed installation downstream of the main distribution board.