The Siemens 5SM2342-0 is a SENTRON 4-pole instantaneous RCD (residual current device) designed for AC systems at 50 Hz. The AC type means it detects sinusoidal residual currents only; no pulsed DC or smooth DC component handling. That's fine for general lighting and heater circuits, but if you've got VFDs, UPS, or rectifier loads downstream, you'll want a Type A or B unit instead.
Depth is 77 mm, width 124 mm, height 90 mm. Installation depth 70 mm means the body sits 7 mm proud of the rail; check gland plate clearance if you're packing a shallow enclosure. Mounts in any position, top or bottom feed.
Thermal derating curve
At 50 °C it's 36 A; at 60 °C it's 34 A; at 70 °C it's 32 A. The -40 °C to 75 °C storage range covers most shipping and idle conditions.
This is a current-production part — no end-of-life notice on record. The SENTRON RCD line is a standard catalog item; availability is stable through distribution.