The Schneider A9L08321 iPRD8r is a three-pole Type 2+3 surge arrester built on MOV technology, designed for IT earthing systems at 400 V AC ±10 %. It handles common-mode transients up to 8 kA maximum discharge current and 2.5 kA nominal. Use it downstream of a main SPD in distribution panels where the neutral-to-ground impedance is high (IT systems) and where you want a second-level clamp plus a very low let-through voltage for sensitive loads.
Type 2+3 means it serves both as the secondary surge protection (Type 2 at the sub-distribution) and as the equipment-level fine protection (Type 3 right at the load), so you can omit a separate third-stage SPD in many cases. The Up protection level <1.8 kV common mode (L/PE) stays well inside typical equipment withstand margins for devices rated 2.5 kV. The temporary overvoltage (TOV) withstand is 337 V for 5 seconds line-to-neutral—useful in IT systems where a ground fault can shift the neutral potential. Phase-to-ground TOV withstand at 1455 V for 200 ms is a safe failure mode (the MOV goes to short-circuit, not flame). Coordination: the iPRD8r expects an upstream overcurrent device. Schneider recommends a 10 A curve C iC60L or a gG 25 A fuse.
Panel wiring and mounting
Clip-on DIN rail mounting, 6 modules wide. Terminals accept 2.5–25 mm² rigid or 4–16 mm² flexible with ferrule. Tightening torque 3.5 N·m. The tunnel terminals accept wiring from top or bottom, which simplifies busbar layout in a crowded panel. Relative humidity 5–95 % non-condensing. The remote signaling contacts are rated 0.25 A / 250 V AC, enough for driving an input on most PLCs.