What this MCCB is and what it does
The Siemens 3VA1225-5EF32-0KC0 is a SENTRON molded case circuit breaker (MCCB) configured for line protection — meaning it's the primary overcurrent and short-circuit safeguard on a feeder or main distribution panel, not a motor-protective device. Its 250 A rated continuous current (Iu) holds flat from 40 °C to 50 °C, then derates to 223 A at 70 °C; that thermal curve matters if your enclosure runs hot. The TM240 thermal-magnetic release handles the time-current coordination — thermal for overload, magnetic for short-circuit — and the shunt trip (STL) auxiliary release lets a remote signal or emergency-stop circuit trip the breaker independently of the overcurrent condition. Breaking capacity is the headline number for this class: 187 kA at 240 V, 121 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V. At 415 V — common in industrial distribution — 121 kA means this breaker can safely interrupt a fault current over 120 000 A without welding its contacts or rupturing the case. That puts it in the high-interrupting range, suitable for large transformer secondaries or busway feeds where available fault current is high. The 3-pole design covers three-phase systems. Rated insulation voltage Ui is 800 V, so it's rated for 690 V line-to-line applications. Two built-in auxiliary switches (HQ type) give you status feedback — open/closed indication for a PLC or panel lamp — without adding an external contact block.
Panel fit and mounting
Footprint: 105 mm wide, 158 mm high, 70 mm deep. That 105 mm width (roughly 4.1 inches) is standard for a 250 A frame MCCB — it occupies three 35 mm DIN-rail modules plus some overhang for the case. The depth of 70 mm means it clears most 200 mm deep enclosures with room for rear busbars. IP40 on the front means protection against tools and wires >1 mm — fine for a dry indoor panel; no washdown rating. Operating temperature range -25 °C to 70 °C. Storage range -40 °C to 80 °C. The derating above 55 °C is already baked into the current table — no extra calculation needed if your ambient stays under 70 °C.
What's included and what's not
The breaker ships with the TM240 overcurrent release and the shunt trip STL installed. The integrated auxiliary trip order code is 3VA9688-0BL33 — that's the specific shunt trip module inside this variant. Two HQ auxiliary switches are factory-fitted. No undervoltage release, no communication module, no phase-failure detection, no ground-fault monitoring, and no trip indicator. If you need those, you're looking at a different order code in the 3VA family. Latching endurance rated at 15 000 cycles — that's the mechanical life for the switching mechanism under no-load or low-current conditions. Not a wear-out concern for a main breaker that cycles a few times a year, but worth noting if it's used for frequent load switching.