What it is and what it does
The Siemens SENTRON 3VM1112-5MH32-0AA0 is a 3-pole molded case circuit breaker (MCCB) with a TM120M thermal-magnetic overcurrent release. It's built for distribution and motor branch-circuit protection in industrial panels — the TM120M release gives you a fixed thermal curve and magnetic trip, no adjustment dials, so it's a set-and-forget device for standard feeder or motor loads. Rated 125 A continuously at ambient temperatures from 40 °C up to 50 °C, with a slight derating curve above that: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. That means in a warm panel you still get nearly full rating — no big step-down until you're past 55 °C. The interrupting ratings are the headline: 187 kA at 240 V AC, 121 kA at 415 V, 76 kA at 440 V, and 17 kA at 500 V. That 187 kA at 240 V is high — it handles a stiff transformer-fed fault without needing a current-limiting fuse upstream. At 415 V the 121 kA still covers most large distribution panels. Maximum frame rating is 2000 A, so this breaker sits in a 2000 A frame but is fitted with a 125 A TM120M trip unit. The 800 V rated insulation voltage (Ui) means it's suitable for 480 V and 600 V class systems with margin.
Integration and mounting
Dimensions: 130 mm height, 76.2 mm width (3 inches), 70 mm depth. The 3-inch width is standard for a 3-pole MCCB in this frame class — it fits the typical panel cutout and bus-bar spacing used across the SENTRON 3VM line. Front IP40 protection keeps out tools and fingers but isn't rated for washdown; install in a sealed enclosure if the environment is wet or dusty. Power loss is 28 W maximum at rated current — that's heat you need to vent in a sealed enclosure. No undervoltage release, no shunt trip, no ground-fault module on this variant; it's a straight thermal-magnetic breaker with no auxiliary functions. Communication function is absent, so no remote tripping or status monitoring without adding external accessories.