Trip unit for ComPacT NSX100-250
The C103TM040C is a TM-D thermal-magnetic trip unit for the Schneider Electric ComPacT NSX100-250 range, rated 40 A at 50 °C. It provides LI protection — thermal overload (L) and magnetic short-circuit (I) — across three protected poles (3D). The fixed instantaneous pickup trips at 500 A, and the long-time pickup is adjustable from 0.7 to 1.0 × In. This is the distribution-grade version, without earth-leakage detection.
The 500 A instantaneous pickup (Ii) is fixed — roughly 12.5 × In — so it clears hard shorts fast but may not coordinate with downstream 10 kA MCBs on a high-fault bus. The TM-D trip unit is non-interchangeable in the field — it's a fixed thermal-magnetic design with a sealed housing. The long-time delay (tr) is fixed at 120–400 s at 1.5 × In and 15 s at 6 × Ir, which suits distribution feeders rather than motor-starting profiles. For motor loads, a TM-G or electronic Micrologic trip unit would be a better fit.
The trip unit mounts into a ComPacT NSX100-250 fixed or plug-in circuit breaker. The breaker itself is IP40 front-face protected (finger-safe), suitable for enclosed panel mounting. The 3D pole configuration means the trip unit protects all three phases but does not include a neutral pole — use a 4P breaker if neutral protection is needed. No auxiliary contacts or shunt trip are integrated; those are add-on accessories that clip onto the breaker side.