What it is and what it does
The Schneider Electric A9Z21480 is an Acti9 iID residual current circuit breaker (RCCB) — a 4-pole unit rated 80 A with 30 mA earth-leakage sensitivity, Type A protection, for 380...415 V AC networks at 50/60 Hz. It clips onto a DIN rail, neutral on the left, and uses a voltage-independent trip mechanism so it clears a ground fault even if the phase voltage collapses.
What the ratings mean for fit
80 A rated current (In) and 30 mA sensitivity is the standard residential/commercial main-switch RCCB spec — it protects the whole downstream board against earth faults while carrying the full load. Type A means it detects pulsating DC residual currents from rectified loads (switched-mode supplies, variable-speed drives, LED drivers) that a plain AC type would miss. Rated conditional short-circuit current is 10 kA (IEC 61008-1), so it withstands a bolted fault up to that level without rupturing, provided the upstream MCB or fuse limits let-through energy. Breaking capacity Idm/Im is 1500 A — that is the RCCB's own ability to interrupt a fault, not the full SCCR; the 10 kA figure governs the installation's fault-withstand rating. Pollution degree 3 means it is rated for conductive pollution or dry non-conductive pollution that becomes conductive due to condensation — typical for industrial control panels and distribution boards not in a sealed clean environment. IP20 body, IP40 in a modular enclosure: no washdown rating, so keep it inside a cabinet.