It carries the N breaking-capacity code — 50 kA Icu at 380/415 V AC 50/60 Hz per IEC 60947-2 — which makes it a distribution-grade MCCB sized for main or feeder protection in commercial and industrial panels where fault levels stay under that threshold. Four poles (4P) with neutral on the left and no integral earth-leakage module. The TM-D trip provides L (thermal overload) and I (magnetic short-circuit) protection; it is not field-interchangeable — the trip unit is fixed at the factory. Mechanical durability is rated 20,000 cycles, with electrical endurance of 10,000 cycles at rated current at 440 V.
The N breaking capacity is the middle tier in the NSX250N frame: 50 kA at 415 V AC, 36 kA at 500 V, 35 kA at 525 V, and 10 kA at 690 V. For a 400 V distribution board with a transformer impedance that limits prospective fault current to, say, 35 kA, this breaker has headroom. At 690 V the 10 kA figure is the hard limit — step up to an S or H frame if your service entrance sees higher. Category A utilisation (no intentional short-time delay) means this breaker is not designed for selective coordination against a downstream device on a delayed trip. For full selectivity in a two-level distribution scheme, pair it with a Category B breaker upstream or use the ComPacT NSX Micrologic electronic trip version that supports short-time delay.