Rated current and breaking capacity — what they mean for your panel
The Siemens SENTRON 3VA1125-6GF42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for a continuous current of 25 A, with no derating needed up to 50 °C ambient — it holds full 25 A at 40 °C, 45 °C, and 50 °C, then drops to 24 A at 55 °C and 60 °C, and 23 A at 65 °C and 70 °C. That temperature curve means you can install it in a warm enclosure without oversizing, as long as the ambient stays under 50 °C. The interrupting ratings are what make this breaker stand out: 220 kA at 240 V, 154 kA at 415 V, 121 kA at 440 V, and 17 kA at both 500 V and 690 V. At 240 V, that 220 kA rating means it can safely clear a fault current that would vaporize a standard industrial breaker — it is sized for high-available-fault installations like large transformer secondaries or busway-fed panels where the prospective short-circuit current is extreme. The TM240 overcurrent release is a thermal-magnetic type, meaning it uses a bimetal strip for overload protection (thermal) and a solenoid for short-circuit protection (magnetic). The 240 designation indicates the magnetic trip threshold is fixed at 240 A — ten times the 25 A frame rating — so it will not nuisance-trip on motor inrush but clears hard faults fast.
Panel fit and integration
At 70 mm deep, 101.6 mm wide, and 130 mm tall, this 4-pole MCCB fits standard distribution panel cutouts. The IP40 front protection means it is dust-protected on the face but not sealed against water — fine for indoor panel mounting, not for washdown areas. Rated insulation voltage is 800 V, so it can be used in 690 V systems with full clearance margins. Maximum power loss is 8.5 W at rated current — negligible for thermal budgeting in a crowded enclosure, but worth noting if you are packing multiple breakers side-by-side with no ventilation.
What the 5SQ2670-2YA06 comparison tells you
The 5SQ2670-2YA06 is a functionally similar 4-pole MCCB from the same SENTRON family, also rated 25 A with a thermal-magnetic release. The deciding difference is the breaking capacity: the 3VA1125-6GF42-0AA0 carries the higher 220 kA at 240 V, while the 5SQ2670-2YA06 is typically rated lower. If your panel's available fault current exceeds 100 kA, the 3VA1125-6GF42-0AA0 is the one you need — the 5SQ2670-2YA06 would not coordinate. Footprint is the same 70 mm × 101.6 mm × 130 mm, so a swap between them requires no enclosure modification, only a check of the fault current study.