What this MCCB carries and where it fits
The Siemens 3VA1225-5GF42-0AC0 is a 4-pole SENTRON molded case circuit breaker rated 250 A continuous, built for line protection in distribution panels. It uses a TM240 thermal-magnetic release — fixed thermal and magnetic trip elements, no electronic adjustment. The interrupting capacity is 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V, so it handles high fault-current scenarios across common low-voltage supply levels. The insulation voltage is rated 800 V, giving headroom for 690 V systems. Full-load power loss is 57 W maximum, which matters for enclosure heat budgeting. This is a line-protection breaker — it sits at the incoming feed or main distribution point, not downstream branch protection. The 4-pole construction covers three-phase plus neutral switching, typical for TN-S or TT systems where the neutral needs to be isolated or switched. The fixed TM240 release means no interchangeable trip units; the breaker is ordered as a single assembly.
Thermal derating and operating range
The breaker holds its full 250 A rating from 40 °C through 50 °C ambient. Above that, it derates: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. If the panel ambient runs hot — say a crowded enclosure near a furnace line — the derating curve tells you the actual continuous current the breaker can carry without nuisance tripping. Operating ambient range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Physical fit and integration
Dimensions: 158 mm high, 140 mm wide, 70 mm deep. The 140 mm width for a 4-pole frame is standard for SENTRON 3VA molded case breakers — it bolts into a panel on a mounting plate or a DIN-rail adapter (not included). The 70 mm depth means it clears most 200 mm deep enclosures with room for rear busbars. The breaker ships with two auxiliary switches HQ (high-quantity contacts) as standard, wired via the front accessory slot. No undervoltage release or ground-fault monitoring version is fitted on this order code.