The 30 mA type A residual current detection catches pulsating DC fault currents — the kind rectified loads (VFDs, switched-mode supplies, single-phase rectifiers) can produce. Type AC devices miss these; type A is the minimum for modern panels with electronics. The 25 A rating and 4-pole switching (neutral is switched too) make it a direct fit for three-phase sub-distribution boards feeding socket circuits or small equipment. Conductor cross-section accepts 0.75 to 35 mm² solid or stranded, which covers everything from 1.5 mm² lighting tails to 10 mm² sub-main cables. Installation depth is 70 mm — check your enclosure depth before committing.
The screw terminals take a 2.5 to 3 N·m torque — a standard screwdriver setting, no special tool. Supply can feed from top or bottom, so rework of existing busbar arrangements is minimal. IP20 applies only when the distribution board is installed with connected conductors — the front face is touch-protected (fingers won't reach live parts), but the terminals are not sealed against dust ingress. The 95% humidity tolerance covers most non-condensing environments.
The 5SU1342-7KC25 carries designations per DIN EN 61346-2 and DIN EN 81346-2 (function F). Energy limiting class 3 indicates it limits let-through energy well — relevant for coordinating with downstream devices. The test button operates down to 195 V, so it can be functionally tested even on a weak supply.