What it is and what it does
The Siemens SENTRON 3VA1220-4EF42-0CA0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection. It carries a TM240 thermal-magnetic overcurrent release, meaning the thermal element handles overloads and the magnetic element handles short circuits — no electronic trip unit to program. The interrupting ratings are substantial: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. That SCCR headroom means it can sit upstream of a high-fault panel without cascading failure, which is exactly what a site electrical engineer wants for selectivity coordination.
Current rating and thermal derating
Rated 200 A at 40 °C, it holds that same 200 A at 45 °C and 50 °C — no derating needed in a typical warm panel. At 55 °C it drops to 194 A, then 188 A at 60 °C, 182 A at 65 °C, and 176 A at 70 °C. If the breaker lives in a hot enclosure next to drives or transformers, that derating curve tells you exactly where you land without guessing. The maximum power loss is 44.5 W, so ventilation matters in a sealed box.
Physical fit and panel integration
Dimensions are 70 mm deep, 140 mm wide, 158 mm high. That's a standard 4-pole MCCB footprint — it'll drop into a SENTRON panelboard or a DIN-rail adapter without re-drilling the gland plate. A food-and-bev process controls engineer checking panel fill factor can count on that width and depth not eating up extra rail space. The 800 V rated insulation voltage covers most 400 V and 690 V systems with margin.