What it is and what it does
The Siemens 5SV4414-0KL is a SENTRON residual current circuit breaker (RCCB) — a 2-pole, AC-type instantaneous device rated for 40 A at 230/400 V AC. It trips on residual currents of 100 mA, protecting against earth faults in circuits where the fault current is sinusoidal AC. The 10 kA short-circuit current rating (SCCR) means it can safely interrupt fault currents up to that level without welding or rupturing, so it coordinates with upstream overcurrent devices in a standard distribution board. The RCCB mounts on a DIN rail (36 mm wide, 2 width units) and fits a standard 70 mm installation depth. It is finger and back-of-hand safe per the protection class, and rated IP20 once installed with conductors connected — typical for enclosed distribution panels.
Ratings and derating
The 40 A rating holds at 40 °C ambient. Above that, the device derates linearly: 38.1 A at 45 °C, 35.59 A at 50 °C, 32.29 A at 55 °C, 28.19 A at 60 °C, 23.3 A at 65 °C, and 17.62 A at 70 °C. If the panel runs warm — near a transformer or in a crowded enclosure — use the 45 °C or 50 °C column to size the load. The operating ambient range is -25 to +45 °C; storage range is -40 to +75 °C. The permissible I²t value is 58 000 A²·s, which gives the upstream breaker a coordination target for let-through energy. The supply can land top or bottom; mounting position is any.
Wiring and compliance
The terminals accept solid or stranded conductors from 0.75 mm² up to 35 mm² — enough for the full 40 A load on a 6 mm² or 10 mm² circuit. The device is silicon-free, which matters for applications where outgassing can contaminate sensitive contacts or optics. Overvoltage category III suits fixed installation downstream of the main distribution board.