It is a 4-pole unit with fully protected neutral (4D), designed specifically for generator protection duty per the manufacturer's application designation. The trip unit provides LI protection: long-time thermal overload (L) adjustable from 0.7 to 1 x In, and fixed instantaneous magnetic short-circuit protection (I) picking up at 520 A. It complies with EN/IEC 60947-2 for low-voltage switchgear and carries an IP40 finger-protection rating on the front face.
The fixed 520 A instantaneous pickup (about 2.08 x In) means the magnetic trip clears short-circuits above that threshold without delay — this is a relatively high ratio, typical for generator applications where inrush from upstream transformers or load banks must ride through without tripping. The long-time delay is fixed at 120 to 400 s at 1.5 x In, which gives a generous thermal band for generator overload profiles. The 4D neutral protection means the neutral pole is fully rated and protected identically to the phase poles — critical for generator paralleling where neutral currents can approach phase levels.
Integration notes for panel builders
The trip unit mounts into a ComPacT NSX250 fixed-mount breaker frame. The neutral position is on the left (4-pole arrangement). The IP40 front face is suitable for enclosed panel mounting; if the panel door is open during maintenance, finger-probe protection is maintained on the trip unit face.