What this MCCB carries and where it fits
The Siemens 3VA1112-5EF36-0KC0 is a 3-pole SENTRON molded case circuit breaker rated for 125 A continuous current with a TM240 thermal-magnetic overcurrent release. The interrupting capacity hits 187 kA at 240 V, 121 kA at 415 V, and 75.6 kA at 440 V — numbers that tell you this breaker is sized for high-fault industrial panels, not light commercial distribution. The 800 V rated insulation voltage (Ui) confirms it belongs on 400/480 V lineups with headroom to spare. It ships with a factory-installed shunt trip (STL) auxiliary release and two auxiliary switches (HQ version). The shunt trip lets a safety PLC or E-stop circuit drop the breaker remotely — common on machine-tool and conveyor infeed panels. No undervoltage release, no ground-fault module, no communication stack. This is a straight line-protection MCCB with a remote-trip option, not a smart breaker.
Thermal derating and panel integration
The 125 A rating holds flat from 40 °C to 50 °C — no derating needed in a typical enclosed panel. At 55 °C it drops to 120 A, at 60 °C to 117.5 A, and at 70 °C to 112.5 A. If your panel ambient runs hot from adjacent drives or transformers, size the load at the 70 °C figure. The front face carries IP40 protection, meaning tools and fingers stay out, but the breaker is not sealed against washdown. Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep. The 76.2 mm width is a standard 3-pole MCCB footprint — it drops into the same DIN or bolt-on mounting pattern as other SENTRON 3VA frames. No rewiring needed if you're swapping from a 3VA1112-5EF32-0CA0; the line and load lugs land in the same positions.
What the interrupting ratings mean for coordination
At 240 V the 187 kA SCCR lets this breaker sit at the main or feeder position in a high-capacity transformer secondary without cascading upstream. At 690 V the rating drops to 17 kA — still adequate for most 690 V drives and motor circuits, but verify coordination with the upstream protective device if your fault current exceeds that. The TM240 release is thermal-magnetic: the thermal element handles overloads (125 A continuous), the magnetic element clears short-circuits. No electronic adjustment, no zone-selective interlocking.