The Siemens 5SU1354-6KV40 is a combined residual-current circuit breaker with overcurrent protection (RCBO) — a single module that packs both a Type A RCD and a B-curve MCB into a 1+N-pole package. It carries a rated residual current IΔN of 30 mA, a breaking capacity of 10 kA, and a thermal-magnetic trip characteristic at B 40 A. The 70 mm depth fits standard distribution boards without crowding the gland plate.
What the ratings mean for fit
Type A detection means it catches pulsating DC fault currents up to 6 mA superimposed on the AC waveform — the minimum for circuits with single-phase rectified loads like washing machines, LED drivers, or EV chargers. The 30 mA IΔN is the standard for personal protection against direct contact (IEC 60364-4-41). The B-curve at 40 A trips between 3 and 5 times rated current (120–200 A magnetic release), sized for resistive or lightly inductive loads where inrush stays moderate — think lighting banks, small heaters, or control transformers. The 10 kA breaking capacity at the rated voltage covers most domestic and light commercial distribution boards (typically 6–10 kA prospective short-circuit current at the final subcircuit).