The 300 mA residual sensitivity makes this a good fit for circuits where a 30 mA RCD would cause nuisance tripping — think distribution sub-mains, feeder circuits to fixed equipment, or lighting banks with higher natural leakage. The AC-type detection handles sinusoidal AC fault currents; it's not listed for pulsating DC or smooth DC faults, so keep that in mind if the load includes rectifiers or VFDs downstream.
Temperature derating and installation
Rated 125 A at 30 °C, but the continuous current drops to 115.62 A at 40 °C, 111.25 A at 45 °C, 106.25 A at 50 °C, 101.25 A at 55 °C, and 96.25 A at 60 °C. The 70 mm installation depth is standard for SENTRON modular devices; the 11 MW width means it occupies eleven 18 mm slots on the DIN rail.