The Siemens SENTRON 5SM3414-0 is a 2-pole residual current circuit breaker (RCCB) rated 40 A at 230 V AC, 50 Hz, with a 30 mA trip sensitivity and a 10 kA short-circuit current rating. It is an instantaneous-type device for AC fault currents, designed to snap onto a DIN rail (REG) in a distribution board. Same part, different passport — this is the standard European-spec unit, current production, and the one you want for a 230 V single-phase submain or feeder where earth leakage protection is required.
The 40 A rating at 40 °C and 45 °C is the headline number, but the thermal derating curve tells the real story for a warm enclosure: at 50 °C it carries 37.6 A, at 55 °C it drops to 35.2 A, and at 60 °C it is 32.8 A. If your distribution board runs hot — say above 45 °C ambient — you need to size up one frame or accept the reduced continuous current.
The 70 mm depth matches standard distribution board cutouts. IP20 applies only when the board is installed and conductors are connected — this is an open-back device, not for standalone outdoor use. The test button requires a minimum 100 V to operate.