The Siemens SENTRON 3VM1112-5EE32-0AA0 is a 3-pole molded case circuit breaker (MCCB) with a TM220 thermal-magnetic release, sized for line protection in distribution panels. It's rated 125 A continuous at 40 °C and carries a 187 kA interrupting capacity at 240 V — that's the short-circuit rating that tells you it can clear a bolted fault on a large transformer secondary without the arc flashing over to adjacent gear.
Ratings and what they mean for fit
The 125 A frame at 40 °C is the continuous current you design the feeder for; it holds flat through 50 °C and only starts to taper at 55 °C (122 A), dropping to 114 A at 70 °C. That means in a warm panel — say 50 °C ambient — you still get full 125 A without derating. The interrupting ratings step down with voltage: 187 kA at 240 V, 121 kA at 415 V, 76 kA at 440 V, 17 kA at 500 V. At 480 V typical of North American industrial panels, you'd interpolate between the 440 V and 500 V figures — still well above most service-entrance fault currents. The TM220 overcurrent release means it's a fixed thermal-magnetic trip — no electronic adjustment, no communication module. That's a simpler, more rugged choice for a fixed-load feeder where you don't need to dial in the trip curve. The 3-pole block handles three-phase circuits; there's no undervoltage release, no ground-fault monitoring, and no trip indicator on this variant.
Panel fit and environment
The case dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — that's a compact 3-pole MCCB footprint. It mounts on a DIN rail or directly to a backplate; the IP40 front face means it's protected against tools and wires >1 mm but not against water spray, so keep it inside a dry enclosure. Operating range is -25 °C to 70 °C; storage from -40 °C to 80 °C. Maximum power dissipation is 23 W — factor that into your enclosure thermal budget if you're packing several breakers side by side.