The Schneider Electric A9L40400 is an Acti9 iPRD40 Type 2 surge arrester, 4-pole, rated for 230/400 V AC at 50/60 Hz. The 40 kA maximum discharge current (common mode L/PE and N/PE) handles direct lightning-induced surges on a TN-C-S earthing system. Nominal discharge is 15 kA per mode — enough for a main distribution board in an industrial or commercial building.
The 4P configuration covers three phases plus neutral, with common-mode protection on each L/PE and N/PE path. The maximum continuous operating voltage is 350 V — that's the steady-state voltage the MOVs can sit across without degrading. Temporary overvoltage (TOV) withstand is 337 V L/N for 5 seconds; above that, the arrester enters a safe failure mode. The protection level Up is under 1.4 kV, which keeps downstream equipment within typical impulse withstand ratings (category III/IV). Mounting is clip-on DIN rail, so it snaps into the same enclosure as the associated circuit breaker. The tunnel terminals accept 2.5 to 35 mm² — solid or stranded — and the tightening torque is 2.5 N.m. The housing is white (RAL 9003), 72 mm wide, 85 mm high, 69 mm deep, and occupies 8 of the 9 mm DIN pitches. IK03 impact rating means it resists 0.35 J — enough for accidental tool contact in a closed panel.
The arrester is certified to EN 61643-11:2012 and IEC 61643-11:2011, with KEMA-KEUR and NF quality labels. That covers the Type 2 test sequence — nominal discharge, TOV withstand, thermal stability. The associated disconnector options are listed: iC60H, iC60N, NG125H, NG125L, NG125N circuit breakers (all 40 A curve C) or gG fuses (63 A or 80 A). The back-up protection must be sized per the manufacturer's table to ensure the arrester clears a fault without venting.