The Schneider Electric A9Z12491 is a 4-pole Acti9 iID residual current circuit breaker (RCCB) rated at 100 A with 100 mA earth-leakage sensitivity, Type AC, instantaneous trip. Rated operational voltage is 380...415 V AC at 50/60 Hz, with a rated conditional short-circuit current of 10 kA and impulse withstand of 6 kV. The voltage-independent residual current tripping technology means it operates without needing a separate power supply — useful on circuits where the neutral might be lost.
The 100 A rated current (In) and 100 mA sensitivity (IΔn) define the two main decisions: the RCCB protects against earth faults, not overloads or short circuits — that's the job of the upstream MCB or fuse. The 100 mA threshold is typical for sub-distribution boards feeding fixed equipment (not socket-outlet circuits, where 30 mA is standard). The instantaneous trip (no time delay) clears fast but can nuisance-trip if the circuit has high inrush or capacitive leakage; for those, a time-delay (S-type) RCCB would be the better pick.
Clip-on DIN rail mount — no screws needed for the rail. Terminals accept double front or back entry: rigid up to 35 mm² front, 25 mm² back; flexible up to 25 mm² front, 16 mm² back. Wire stripping length is 14 mm for both top and bottom connections. The IP20 body (IP40 in modular enclosure) is fine for dry indoor panels; not for washdown zones.
The A9Z12491 is listed as current-production (active lifecycle stage). No official successor or alternate MPN is recorded — this is the active order code for the 100 A 4P Type AC iID RCCB in the Acti9 range.