What this cartridge does
The A9L1H900 is a Type 1+2 surge protection cartridge from the Acti9 iPRD1 25r family, designed for L-N protection on 240 V AC 50/60 Hz distribution networks. It handles a 25 kA impulse current (Iimp) per pole and clamps the voltage protection level to under 1.5 kV differential mode. The MOV + GDT technology gives it a <100 ns response time, and it withstands a 442 V temporary overvoltage for 120 minutes before failing safe. That 25 kA Iimp rating means it's sized for direct lightning-strike energy at the service entrance — not just secondary switching surges — so it belongs on the main distribution board, not a sub-panel.
This is the cartridge-only piece — it plugs into the iPRD1 25r 3P or 3P+N base module (sold separately). The cartridge itself measures 36 mm wide by 73.5 mm deep by 45 mm high, which is 4 standard 9 mm pitches on a DIN rail. The white RAL 9003 thermoplastic housing matches the Acti9 family aesthetic. Local status is read from two mechanical flags: green for operating state, red for fault indication — no power needed to check it.