What this MCCB carries and where it fits
The Siemens SENTRON 3VA1112-4EF36-0BH0 is a 3-pole molded case circuit breaker rated for 125 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. It's built for line protection — meaning it sits at the feeder or main distribution point, not downstream for motor or branch-circuit duty. The 125 A rating holds flat from 40 °C up to 50 °C, then derates to 112.5 A at 70 °C, so in a warm enclosure you still have headroom. Breaking capacity is 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V. That 121 kA at 240 V covers high-fault utility feeds; the 75.6 kA at 415 V handles most industrial distribution panels without needing a current-limiting fuse upstream. The 800 V rated insulation voltage (Ui) means it's rated for 690 V line-to-line systems. It includes an undervoltage release (UVR) as the auxiliary release design — that's the coil that drops the breaker if control voltage falls below a threshold, common for emergency-stop or undervoltage protection schemes. The auxiliary contact block is a 2 aux + 1 trip alarm switch (HQ version), giving you two form-C signals plus a dedicated alarm contact that changes state only on a fault trip. Mounts on a DIN rail or panel-mount base. The front face carries an IP40 rating — fine for a clean indoor panel, but not for washdown or dust. Depth is 70 mm, width 76.2 mm, height 130 mm, so it fits standard SENTRON 3VA panel cutouts.