What this MCCB is and what it does
The Siemens SENTRON 3VA1220-6EF42-0AJ0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current Iu of 200 A at 40 °C ambient. It uses a TM240 thermal-magnetic trip unit — the thermal element handles overloads, the magnetic element handles short-circuits — so it's a straightforward fit for feeder and distribution panels where you don't need electronic adjustability or communication. Breaking capacity is substantial: 220 kA at 240 V, 154 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V. That's enough for high-fault utility connections or transformer secondaries without cascading upstream breakers. The 800 V rated insulation voltage (Ui) means it's comfortable on 480 V and 600 V class systems with headroom.
Thermal derating and real-world current
The 200 A rating holds flat from 40 °C through 50 °C. Above that it derates: 194 A at 55 °C, 188 A at 60 °C, 182 A at 65 °C, 176 A at 70 °C. If your panel ambient runs hot — say inside a non-air-conditioned enclosure near a furnace line — that 176 A at 70 °C is the number to size against, not the catalog 200 A.
Physical fit and auxiliary contacts
Dimensions are 140 mm wide, 158 mm high, 70 mm deep. It's a standard SENTRON 3VA frame size — mounts on a DIN rail or panel-mount baseplate. The auxiliary contact block is factory-fitted: 2 auxiliary switches plus 1 trip alarm switch (HP type). That gives you a remote status signal for the breaker's open/closed state and a separate contact that closes only on a trip event, which is useful for alarm annunciation or PLC input without extra wiring. Front protection is IP40 — sealed against tools and small solids, but not washdown. Fine for a dry indoor panel; don't put it in a food-processing washdown zone without an enclosure.