What this MCCB brings to the panel
The Siemens 3VA1125-5EF32-0AF0 is a 3-pole SENTRON molded case circuit breaker rated for 25 A continuous at 40 °C with a TM240 thermal-magnetic release. It's designed for line protection — think feeder circuits, distribution panels, and branch protection where you need a solid interrupting rating without overcomplicating the BOM. The interrupting capacity is the headline here: 187 kA at 240 V AC, 121 kA at 415 V, and still 75.6 kA at 440 V. That's serious fault-clearing muscle for a 25 A frame — it handles high available fault currents without needing a current-limiting fuse upstream, which simplifies coordination studies. At 500 V and 690 V the rating drops to 17 kA, so watch your system voltage if you're spec'ing this into a 690 V distribution — the SCCR headroom narrows fast above 440 V.
Thermal derating and real-world current
The 25 A rating holds from 40 °C through 50 °C ambient. At 55 °C it derates to 24 A, and at 70 °C it's 23 A. That's a shallow derating curve — you don't lose much headroom in a warm enclosure, which matters when the panel sits near a furnace line or in a non-conditioned electrical room. Rated insulation voltage is 800 V, and the operating range spans -25 °C to 70 °C. Storage tolerance goes from -40 °C to 80 °C — fine for warehouse staging or seasonal shutdowns.
Physical fit and auxiliary complement
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — a standard 3-pole MCCB footprint that drops into most SENTRON distribution blocks and panelboards without re-drilling the mounting plate. It ships with one auxiliary switch and one trip alarm switch (HQ type) factory-installed. That gives you a remote status contact for the PLC or BAS without buying a separate accessory kit. No undervoltage release, no ground-fault module, no communication function — this is a straight line-protection breaker, not a smart unit. Power loss is 8.5 W maximum at rated current — modest enough that ventilation in a standard IP3X enclosure handles it, but worth checking if you're packing six of these side-by-side in a tight gutter space.