The Schneider Electric A9L20122 is the replacement cartridge for the Acti9 iPRD20r 3P and 4P surge protective devices, specifically for IT earthing systems. It's a Type 2 SPD cartridge using MOV technology, rated for a maximum continuous operating voltage of 460 V (Uc) and a nominal discharge current of 5 kA (In).
The 460 V Uc (maximum continuous operating voltage) means this cartridge is built for 230...400 V AC 50 Hz networks where the line-to-neutral voltage can ride up to 460 V without the MOV degrading — that's typical for IT systems where the neutral isn't solidly grounded and phase voltages can float higher than a TN system. The Type 2 classification (IEC 61643-11) means it handles induced surge currents from switching or indirect lightning strikes, not direct hits — that's what the 20 kA maximum discharge current (Imax) covers. Response time under 25 ns means it clamps fast enough to protect sensitive electronics downstream.
The cartridge plugs into the iPRD20r base module — 18 mm wide (2 x 9 mm pitches), 60 mm deep, 60 mm tall. Front-face IP20, so it's fine inside a standard IP54 or IP65 enclosure. Colour-coded flag indicator (white/red) gives local visual status without opening the panel door. Material is PBT (polybutylene terephthalate), rated for -25 to 60 °C operating ambient and up to 2000 m altitude. CE marked, designed to IEC 61643-11 and EN 61643-11.