125 A MCCB with serious fault current headroom
The Siemens 3VM1112-5EE42-0AA0 is a 4-pole SENTRON molded case circuit breaker rated 125 A continuous at 40 °C, with a TM220 thermal-magnetic trip unit that gives you an adjustable instantaneous pickup up to 1,250 A. What sets this one apart is the interrupting capacity: 187 kA at 240 V AC, 121 kA at 415 V, and still 76 kA at 440 V. That kind of headroom means it handles high-fault utility feeds or transformer secondaries without cascading failure upstream — a real asset in an industrial MCC lineup where the available fault current is known to be stiff.
What the ratings mean for your panel
The 125 A frame is rated continuously at 125 A all the way up to 50 °C, then it derates gradually — 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. If your panel runs hot near the top of a sealed enclosure, you still keep 114 A of continuous capacity. The 690 V rated insulation voltage (Ui) means it's comfortable on 480 V or 600 V class systems with margin. At 500 V AC the breaking capacity drops to 17 kA, so check your available fault current if you're on a 480 V or 500 V service — the 440 V number (76 kA) is the more relevant benchmark for most North American 480 V panels.
Physical fit and panel integration
Dimensions: 130 mm tall, 101.6 mm wide, 70 mm deep. The 4-pole width (101.6 mm or 4 inches) is the standard 4-pole MCCB footprint — it'll drop into a panel that's laid out for a 4-pole SENTRON or similar frame. IP40 on the front means it's protected against tools and solid objects larger than 1 mm, but not sealed against moisture; keep it in a dry indoor enclosure. No communication function, no motor drive option, no ground-fault monitoring built in — this is a straight thermal-magnetic breaker for basic overcurrent protection.
No-frills line protection — what you get and what you don't
The product version is explicitly 'Line protection' — not a motor circuit protector, not a switch-disconnector. The TM220 release gives you a fixed thermal element and an adjustable magnetic pickup (li max 1,250 A), but no electronic trip unit, no zone-selective interlocking, no power metering. If your application needs selective coordination downstream of a transformer, the 187 kA at 240 V gives you the short-circuit rating to coordinate with smaller branch breakers. But if you need adjustable long-time and short-time delays for full selectivity, you'd be looking at an electronic-trip SENTRON 3VA instead. This one is for straightforward feeder or main breaker duty where the available fault current is high and the trip curve is simple.