What this MCCB is and what it protects
The Siemens SENTRON 3VA1050-4ED42-0DA0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection — meaning it sits at the feeder or main distribution point, not at a motor or branch load. Its job is to clear faults before they cascade upstream, and the breaking capacities here are the numbers that tell you whether it holds coordination with the upstream transformer or generator. Rated continuous current Iu is 50 A, and it holds that rating from 40 °C through 50 °C ambient — no derating needed in a warm panel. At 55 °C it still carries 48 A, and at 70 °C it carries 45 A. That thermal curve matters if this breaker lives near other heat sources or in a non-climate-controlled enclosure. The overcurrent release is the TM210, a thermal-magnetic design — thermal for overloads, magnetic for short-circuits. No electronic trip unit here, so no adjustable curves or communication. Simple, field-proven, and less to fail in a high-vibration environment.
Breaking capacity — the real selectivity numbers
At 240 V this breaker interrupts 121 kA. At 415 V it manages 75.6 kA. At 440 V it drops to 52.5 kA, and at 690 V it's 11.9 kA. These are the values you need for a selectivity study — not the catalogue Icu alone, but the actual system voltage you're coordinating. If your panel feeds a 690 V drive bus, the 11.9 kA figure is the one that governs fault clearance.
Panel fit and integration notes
Width is 101.6 mm, height 130 mm, depth 70 mm. The front face carries IP40 protection — fine for a clean indoor panel, but keep it behind a sealed door if the enclosure sees washdown or dust. No auxiliary contact is fitted as standard (order code 3VA9608-0BB25 if you need remote status). An undervoltage release (UVR) is included; verify the coil voltage against your control supply before wiring. No phase-failure detection, no ground-fault monitoring, no communication module. This is a straight line-protection breaker — thermal-magnetic, no electronics.