250 A SENTRON MCCB — Line Protection with Shunt Trip
The Siemens 3VA1225-4GF42-0JA0 is a 4-pole SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current (Iu) and configured for line protection — meaning it guards the feeder or main distribution against overload and short circuit, not a specific motor or load group. Its TM240 thermal-magnetic release provides fixed thermal and magnetic trip settings, so the breaker is sized for a 250 A bus without needing interchangeable trip units — a decision that simplifies panel BOMs and reduces spare-part variety. Breaking capacity reaches 121 kA at 240 V AC, 75.6 kA at 415 V, 25 kA at 440 V, and 11.9 kA at 690 V — figures that determine whether this MCCB can interrupt a fault without upstream fuses or a larger-frame breaker ahead of it.
Thermal Derating and Continuous Current
The 250 A rating holds at ambient temperatures up to 50 °C; above that, derating applies: 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C — so for a panel that runs warm (common in compact switchgear), the actual continuous capacity is lower than the nameplate. Rated insulation voltage (Ui) is 800 V, which covers 480 V and 600 V class systems with margin; the operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C.
Integrated Shunt Trip — No Auxiliary Contacts
This version ships with a factory-integrated shunt trip (STL) release, order code 3VA9688-0BL32, for remote tripping via a control signal — useful in emergency-stop chains or supervisory shutdown schemes. It does not include auxiliary contacts (: no trip indicator: without auxiliary contact version), so if you need status feedback to a PLC or indication lamp, plan for a separate auxiliary switch block or external contactor mirror. No undervoltage release, no phase-failure detection, no ground-fault monitoring, and no communication function — this is a straight line-protection MCCB with a single remote-trip input.
Mechanical Endurance and Panel Fit
Rated for 15,000 mechanical operations (latching endurance), which is typical for a distribution MCCB — not a switching device for frequent load cycling, but fine for infrequent isolation and fault clearance. Dimensions: 140 mm wide, 158 mm high, 70 mm deep — a 4-pole frame that fits standard Siemens 3VA mounting accessories and occupies roughly the same panel footprint as other 250 A SENTRON breakers. Front protection is IP40, meaning tools and fingers are kept out of the breaker face; the rest of the enclosure determines the overall panel IP rating.