What this MCCB is and what it does
The Siemens 3VA1112-4EF32-0AD0 is a SENTRON molded case circuit breaker (MCCB) for line protection, rated at 125 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. Its three poles handle three-phase circuits up to 800 V insulation voltage (Ui). The 121 kA breaking capacity at 240 V gives substantial fault-interrupting headroom at low-voltage distribution levels; at 415 V it still clears 75.6 kA, and at 690 V it holds 11.9 kA — enough for most industrial secondary-distribution panels.
Ratings that drive the fit
The TM240 release means the thermal pickup is fixed at 125 A (the Iu rating), with magnetic trip factory-set to a multiple of that — typical for motor or feeder protection where you want a defined short-circuit threshold. The 125 A holds across 40 °C to 50 °C ambient without derating; above that it steps down to 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C. If your panel ambient runs hot, the 70 °C figure (112.5 A) is the one to size against. The three auxiliary switches (HQ type) are built in — no separate add-on module required for status feedback to a PLC or remote I/O. The front face carries IP40 protection, so it's suited for clean indoor panels; not for washdown zones.
Panel fit and integration
Dimensions are 130 mm high, 76.2 mm wide, 70 mm deep — a standard 3-pole MCCB footprint that fits most DIN-rail or panel-mount enclosures without re-drilling. The 70 mm depth is shallow enough for compact distribution boards. Operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C.