The A9N21758: This is an add-on residual current device (RCD) — the Vigi DPNc — designed to clip onto the side of a compatible MCB (the DPNc series) to provide earth-leakage protection in a single module width. It is not a standalone RCBO; it requires a mechanical and electrical connection to the matching MCB via the screw terminals. The 40 A rated current and 300 mA sensitivity make it a group-incomer device — typically installed at the head of a sub-distribution board to protect multiple downstream circuits against earth faults, not for individual final-circuit protection where 30 mA is standard. The impulse withstand voltage is 4 kV, conforming to EN/IEC 61009-1 — this is the standard for residual current operated circuit breakers with integral overcurrent protection, though this unit is the add-on block only. The voltage-independent tripping technology means the RCD will trip on residual current even if the phase voltage is lost — a safety advantage in fault conditions where the neutral may remain live.
Mounts via clip-on to a DIN rail — standard 35 mm symmetrical rail. The 3P+N poles description with neutral on the left means it occupies four module positions (9 mm pitches each, 6 total per the spec, so 54 mm width). Depth is 70 mm, height 82 mm.
Relative humidity tolerance is 95% at 55 °C. Maximum operating altitude is 2000 m. Standards compliance includes EN/IEC 61009-1 and EN/IEC 61009-2-1.