The Siemens 5SU1654-6KV40 is a combined residual-current and overcurrent protective device — an RCBO in the FI/LS line — rated 40 A B-curve with a 300 mA Type A residual trip and a 10 kA breaking capacity. Type A detection covers pulsating DC residual currents up to 6 mA plus sinusoidal AC, which is the standard requirement for most single-phase final circuits with electronic loads (switched-mode supplies, variable-speed drives on lighting or small motor circuits). The B-curve magnetic release trips between 3 and 5 times rated current, so it clears short-circuit faults fast enough to coordinate with a 10 kA upstream MCB without nuisance tripping on motor inrush.
Panel integration and wiring
The 1+N-pole format (switched phase plus switched neutral) fits a 70 mm deep enclosure — standard for flush-mount consumer units and small distribution boards. The neutral pole opens and closes with the phase, so no separate neutral bar connection is needed downstream of the device. Spring-cage terminals accept 0.75–25 mm² conductors; strip length 8–10 mm avoids whiskers under the clamp.