What it is and what it does
The Siemens 3VA1050-3ED42-0CC0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. Four poles, rated 50 A at 40 °C, with a breaking capacity of 75.6 kA at 240 V AC — that's the short-circuit current it can safely interrupt without welding contacts or venting plasma into the enclosure. At 415 V it still holds 52.5 kA, and at 690 V it's 7.5 kA, so the voltage you're protecting determines the fault-clearing margin. It ships with an undervoltage release (UVR) and two auxiliary switches HQ built in — no separate add-on modules to order for basic status feedback or undervoltage trip. The UVR means the breaker drops if control voltage falls below the dropout threshold, which is common in safety circuits or emergency-stop chains where a loss of control power should open the main feed.
Ratings that matter for panel fit
Dimensions: 130 mm tall, 101.6 mm wide, 70 mm deep. That's a 4-pole MCCB that fits a standard 100 mm-wide DIN-rail slot — the width is the critical number for multi-breaker rows. Depth of 70 mm means it clears most 200 mm-deep enclosures with room for wiring gutters. Thermal derating is published: it holds 50 A from 40 °C up to 50 °C, then drops to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. If your panel ambient runs above 50 °C, size the load or the breaker accordingly — the 50 A rating is not a hard limit across the full temperature range. Insulation voltage rated 800 V, so the breaker is suitable for 690 V systems with margin. Power loss at full load is 17.1 W — that's the heat you need to vent from the enclosure; for a multi-breaker panel, sum the losses and check the thermal budget.