The Schneider Electric C163MG125 is a TM-G thermal-magnetic trip unit for the ComPacT NSX160 molded-case circuit breaker frame, rated 125 A at 40 °C and built to EN/IEC 60947-2. It is a 3-pole (3D protected poles) unit designed specifically for generator protection — the TM-G curve accounts for the higher inrush and sustained overload profile typical of generator feeders, which a standard TM-D or TM-A trip might nuisance-trip on. Protection is LI (long-time and instantaneous): the thermal element handles overloads with an adjustable Ir pickup from 0.7 to 1.0 x In (87.5–125 A), and the fixed tr delay sits at 120–400 s at 1.5 x In. The magnetic element picks up at a fixed 440 A — that's about 3.5 x In, which is deliberately higher than a standard distribution breaker to ride through generator start-up transients without tripping.
This is a plug-in trip unit for the ComPacT NSX160 fixed-mount breaker — it swaps into the same cradle as other NSX160 trip units. The breaker itself is DIN-rail or screw-panel mounted; the trip unit adds no extra panel space. That covers most indoor industrial enclosures, including unheated warehouses. Class II shock protection means no earth connection is required on the trip unit itself.