The Schneider Electric A9Z31491 is a 4-pole Acti9 iID residual current circuit breaker (RCCB) rated for 100 A continuous current with 30 mA earth-leakage sensitivity. It is a voltage-independent, instantaneous-trip device — meaning it does not need an external power supply to detect a fault and will clear a ground leak the moment it exceeds 30 mA. That 30 mA threshold is the standard for personal shock protection in most residential and light-commercial panels (IEC 60364 specifies 30 mA for socket-outlet circuits). The Type A-SI (Super Immunised) designation means it handles pulsed DC fault currents from electronics (switch-mode supplies, VFDs, LED drivers) without nuisance tripping from high-frequency leakage, while still tripping on the 50/60 Hz AC residual.
Rated operational voltage is 380...415 V AC at 50/60 Hz, which covers the common three-phase 400 V line-to-line supply across Europe and much of Asia. The 10 kA rated conditional short-circuit current (SCCR) means the RCCB can withstand a fault up to 10 kA without rupturing, provided an upstream overcurrent device (MCB or fuse) clears the fault within its let-through rating — standard for a distribution board fed from a 100 A or smaller transformer. Insulation voltage (Ui) is 500 V AC, and impulse withstand (Uimp) is 6 kV, which is the typical coordination level for a Type 2 surge arrester downstream. Mechanical durability is 20,000 cycles; electrical durability under AC-1 resistive load is 10,000 cycles. For a fixed-installation RCCB that is not switched daily, that is a lifetime rating — the part will outlast the panel's service life in normal use. The 8/20 µs impulse withstand of 3,000 A confirms it survives surge events from nearby lightning or switching transients without damage.
Clip-on mounting to a 35 mm DIN rail, 4-pole wide (72 mm width, 8 x 9 mm pitches).