The Schneider Electric A9L40281 is a Type 2 surge arrester from the Acti9 iPRD PV-DC range, designed specifically for photovoltaic DC circuits. The 1000 V DC rated operational voltage covers the typical string voltage of commercial PV arrays, and the integrated disconnector means you don't need a separate external disconnect — the unit itself isolates the MOV cartridge for safe replacement.
The 15 kA nominal discharge current (In) is the rating for repeated surge survival. The 40 kA maximum (Imax) is the single-event survival limit.
This is a clip-on DIN rail mount unit, 2-pole width, occupying 6 x 9 mm pitches (54 mm wide). The tunnel-type terminals accept rigid conductors from 2.5 mm² up to 25 mm², or flexible with ferrule up to 16 mm² — sized for the typical PV array wiring. The white/red local flag gives a visual indication of cartridge status — white is good, red means the MOV has degraded and the cartridge needs replacement.