It's the interchangeable brain that sets the breaker's overload and short-circuit protection — you swap it into the fixed NSX base without pulling the breaker out of the panel. Rated 40 A at 50 °C on a 4-pole 3D configuration (three protected poles, neutral unprotected), it's built for distribution duty in AC or DC networks up to 690 V AC or 750 V DC. The LI protection profile gives you adjustable long-time thermal pickup (0.7–1 x In) with a fixed delay curve, and a fixed instantaneous magnetic pickup at 500 A — no dials to mis-set on the magnetic side, which simplifies coordination on a standard panel build.
Deployment context and environment
This trip unit lives inside a fixed-mount ComPacT NSX breaker in a panel or enclosure. Class II insulation (double-insulated) so no earth connection required on the trip unit itself — one less wire to chase in a crowded panel.