What this MCCB is and what it does
The Siemens SENTRON 3VA1225-6EF32-0AE0 is a 3-pole molded case circuit breaker (MCCB) rated for a continuous current Iu of 250 A and an insulation voltage Ui of 800 V. It is configured for line protection — meaning it guards the feeder or main distribution against overload and short-circuit, not a specific motor or load group. The overcurrent release is a fixed thermal-magnetic TM240, so the thermal pickup is factory-set around the 250 A mark with a maximum adjustable response time tr of 1 second. The breaking capacity tells you where this breaker can sit in a network. At 240 V it interrupts 220 kA — that is a high-fault-current rating for a main breaker close to a large transformer or a utility feed. At 415 V the rating drops to 154 kA, at 440 V to 36 kA, and at 690 V to 17 kA. The 220 kA and 154 kA figures are the ones that matter for most industrial low-voltage distribution; the 690 V number is relevant only for specialized 690 V lineups (e.g., mining or marine). Thermal derating is documented across the operating range: the breaker holds a full 250 A up to 50 °C ambient, then steps down to 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. If your panel internal ambient runs above 50 °C, the continuous load must be capped accordingly — a common oversight when packing breakers into a sealed enclosure.
Mounting and integration
The breaker measures 105 mm wide, 158 mm high, and 70 mm deep. It mounts on a DIN rail or directly to a backplate via the standard 3VA footprint. The front face carries an IP40 protection class, so it is suited for installation inside a cabinet where no water jets or dust ingress are expected. The enclosure depth of 70 mm means it will fit in shallow back-panel enclosures where deeper MCCBs would conflict with the gland plate or door swing. Four high-quality auxiliary switches (HQ) are built in, giving status feedback for remote monitoring or PLC inputs. There is no undervoltage release, no voltage trigger, no shunt trip, no ground-fault monitoring, and no communication module on this variant — it is a straight thermal-magnetic line-protection breaker with aux contacts only. If you need undervoltage or shunt-trip capability, this order code does not carry them; you would step to a different 3VA suffix.