The C104TM050C is a TM-D thermal-magnetic trip unit for the ComPacT NSX100...250 range, rated 50 A at 50 °C, 4 poles 4D. It provides LI protection — thermal overload (L) and magnetic short-circuit (I) — per EN/IEC 60947-2. The 50 A rating at 50 °C means this trip unit is sized for a 50 A continuous load in a 50 °C ambient; if your panel runs hotter, you'll need to derate or step up to the next rating.
Mounts fixed into ComPacT NSX100...250 circuit breaker frames. The trip unit is a plug-in module — no wiring to the breaker itself, just snap it into the cradle. Neutral position is left, which matches standard panel layout for 4-pole breakers where the neutral lug is on the left side. IP40 front face keeps out tools and fingers; the breaker body itself handles the enclosure seal.
The long-time pickup (Ir) is adjustable from 0.7 to 1 x In, so you can dial the 50 A trip unit down to 35 A if the load is lighter — that's one SKU covering a range of feeder sizes. The instantaneous pickup (Ii) is fixed at 500 A (10 x In), which gives a good balance between nuisance trip avoidance and short-circuit protection for distribution feeders. Thermal delay (tr) is fixed at 120-400 s at 1.5 x In and 15 s at 6 x Ir — no field adjustment on the time curve, so coordination studies need to account for the fixed band. Rated operational voltage is 690 V AC 50/60 Hz and 750 V DC, covering most industrial distribution voltages up to 600 V class.