The Schneider Electric A9L1C325 is a Type 1 + 2 surge arrester from the Acti9 iPRD1 range, designed for main distribution boards in TN-C earthing systems. It clamps onto a DIN rail and handles the full lightning impulse current (25 kA Iimp) plus the follow current from the mains (50 kA) without failing — that's the short-circuit withstand rating, not just a let-through number. The gas discharge tube (GDT) technology triggers in under 100 ns, which means it starts shunting energy before the rising edge of a surge can damage downstream equipment. The 3-pole (3P) configuration covers all three phases against common-mode events.
The 25 kA nominal discharge current (In) coordinates with downstream Type 2 arresters. The 65 kA maximum discharge current (Imax) is the one-shot survival limit.