The C063L4WM is the bare frame of a ComPacT NS630b new generation — a 630 A, 4-pole, withdrawable air circuit breaker intended for distribution duty. It ships without a trip unit or any protection module, so you pair it with a separate control unit (e.g., Micrologic) to set the protection curve. That makes it a chassis-level part: you specify the frame once and swap trip units later without pulling the breaker out of the switchgear. Rated 630 A at 50 °C with a 150 kA Icu at 415 V AC, this frame sits at the high end of the ComPacT NS630b line — it handles heavy feeder or main-breaker duty in industrial LV switchboards. The 150 kA short-circuit rating at 415 V means it can be installed upstream of multiple sub-feeders without worrying about cascading failure during a fault. The withdrawable chassis pulls out for inspection or swap without unbolting busbars — a real time-saver on a live panel where every minute of downtime costs production. Mounts on a backplate with 70 mm connection pitch, 306 mm wide, 260 mm tall, 147 mm deep. IP40 front face, IK07 impact resistance.
But for selective coordination you also care about Ics (service breaking capacity), which is the same 150 kA at 415 V. That means after clearing a 150 kA fault, the frame is still rated to carry and switch its full 630 A load — no derating needed. That's unusual at this level; many breakers drop Ics to 50% or 75% of Icu. Short-time withstand (Icw) is 19.2 kA for 1 second. That's the current the frame can carry during a delayed trip — important for zone-selective interlocking or when coordinating with downstream molded-case breakers. Category A utilization means it's not intended for frequent switching of motor starts; it's a distribution breaker, not a motor-circuit protector.
Environmental and installation constraints
Overvoltage category III means it's suitable for fixed-installation distribution boards, not just downstream equipment. Power losses are 34 W at rated current — not negligible in a sealed enclosure. If you're packing multiple frames in a cubicle, factor that heat into your ventilation calc.