The C253TM200C is a TM-D thermal-magnetic trip unit from the Schneider Electric ComPacT NSX100...250 range, rated 200 A at 50 °C for a 3-pole 3D configuration.
Protection profile and what it means on the line
The long-time pickup (Ir) is adjustable from 0.7 to 1.0 x In, so the 200 A unit can be set down to 140 A to match a downstream load without swapping the trip unit. The instantaneous pickup (Ii) is adjustable from 5 to 10 x In, meaning the magnetic trip can be set anywhere from 1000 A to 2000 A. The long-time delay (tr) is fixed at 120 to 400 seconds at 1.5 x In, with a 15-second minimum at 6 x Ir — a thermal curve shaped to coordinate with downstream molded-case breakers without overlapping the cable damage curve.