The C256TM250C is a thermal-magnetic trip unit from the Schneider Electric ComPacT NSX250 range, rated 250 A at 50 °C. It provides LI protection — thermal overload (L) and magnetic short-circuit (I) — in a 4-pole, 3D configuration (three protected poles, neutral unprotected). The TM-D trip unit is fixed-mount, designed for distribution applications per EN/IEC 60947-2.
The 250 A rating at 50 °C sets the continuous current capacity for this trip unit in a 50 °C ambient — if your panel runs hotter, expect derating per the manufacturer's curve. The LI protection scheme means you get adjustable long-time pickup (Ir) from 0.7 to 1.0 x In and adjustable instantaneous pickup (Ii) from 5 to 10 x In, giving you selectivity tuning for downstream breakers. The 690 V AC / 750 V DC rated operational voltage covers most industrial distribution voltages, including 480Y/277 V and 600 V systems common in North America, plus DC bus applications up to 750 V.