What it is and what it does
The SENTRON 3VM1112-3EE42-0AA0 is a 4-pole molded case circuit breaker (MCCB) designed for line protection in industrial power distribution. It carries a TM220 thermal-magnetic overcurrent release, meaning it combines a thermal element for overload protection with a magnetic element for short-circuit interruption. Rated at 125 A at 40 °C, it handles continuous loads up to that current in a 40 °C ambient, with gradual derating to 114 A at 70 °C. The interrupting ratings are substantial: 76 kA at 240 V, 53 kA at 415 V, 32 kA at 440 V, and 12 kA at 500 V. The rated insulation voltage is 800 V, so it's suitable for 480/277 V and 400/230 V systems with headroom.
Mounting and integration
The breaker measures 101.6 mm wide, 130 mm high, and 70 mm deep. Front protection is IP40, so it's protected against tools and small wires entering the front but not sealed against dust ingress — standard for panel-mount MCCBs. The 4-pole design allows it to switch all three phases plus neutral in a 3-phase 4-wire system. No undervoltage release, no voltage trip, no communication function, and no ground-fault monitoring — this is a basic thermal-magnetic breaker for straightforward feeder or branch protection. The TM220 release is a fixed thermal-magnetic type; no interchangeable trip units here.