4-pole MCCB with UVR for line protection
The Siemens SENTRON 3VA1050-4ED42-0CC0 is a 4-pole molded case circuit breaker rated for a continuous current of 50 A at 40 °C, with a TM210 thermal-magnetic overcurrent release and a factory-fitted undervoltage release (UVR). It's set up for line protection duty — no ground-fault monitoring, no N-conductor protection, no comms module. The 121 kA interrupting rating at 240 V means it can handle high-fault utility feeds without cascading upstream; at 415 V it still breaks 75.6 kA, and at 690 V it's 11.9 kA. That's a lot of headroom for a 50 A frame, which is exactly what you want when the available fault current on site is unknown or high.
Thermal derating and panel fit
The 50 A rating holds flat from 40 °C to 50 °C, then steps down to 48 A at 55 °C, 47 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. If the panel runs hot — say a packed enclosure near a furnace line — that derating curve tells you exactly where you land. Dimensions are 130 mm high, 101.6 mm wide, 70 mm deep, which is the standard 4-pole SENTRON 3VA footprint. IP40 on the front means it's splash-resistant from the panel face but not sealed; keep it inside a rated enclosure.
Auxiliary contacts and release configuration
This unit ships with two auxiliary switches (HQ type) and the undervoltage release already integrated — the UVR order code is 3VA9608-0BB24. No voltage trip, no phase-failure detection, no communication function. The TM210 release is a thermal-magnetic fixed-trip design, so you're not adjusting the magnetic pickup in the field. The latching endurance is rated at 15,000 operations, which is typical for a distribution-grade MCCB — not a switching duty cycle, but fine for infrequent manual isolation and automatic fault clearing.