What it is and what it does
The Siemens SENTRON 3VA1112-6MH32-0KH0 is a 3-pole molded case circuit breaker (MCCB) designed specifically for starter protection — meaning it's built to sit ahead of a motor starter combination, handling both the short-circuit and overload protection for the motor branch circuit. Rated 125 A continuously at 40 °C, it carries a 220 kA interrupting rating at 240 V AC and 154 kA at 415 V AC, so it can clear high-fault currents without upstream coordination issues in most industrial distribution panels.
Ratings that matter for fit
The 125 A rating holds flat from 40 °C through 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C — so in a warm enclosure you lose about 9% at the top end. The 220 kA at 240 V is the headline number, but the 154 kA at 415 V is the one that matters for most European or 400 V-class panels; at 690 V it drops to 7.5 kA, which still covers most motor-starting duty but not a high-fault industrial bus. Insulation voltage is rated 800 V, so the breaker is electrically rated for 690 V systems with margin. Power loss at full load is 28.1 W maximum — factor that into enclosure thermal calculations if you're packing several breakers on a DIN rail.
Built-in auxiliaries and releases
This variant ships with a shunt trip release (STL) for remote tripping, plus 2 auxiliary switches and 1 trip alarm switch — all factory-integrated. That means you don't need to order separate accessory kits for status feedback to a PLC or for an emergency-stop circuit that cuts power to the breaker coil. The auxiliary switch configuration (2 form-C contacts plus a dedicated alarm contact) covers most panel-wiring schemes without extra terminal blocks.
Panel fit and dimensions
Width is 76.2 mm (3 in), depth 70 mm (2.76 in), height 130 mm (5.12 in) — a standard 3-pole MCCB footprint that drops into most SENTRON panelboards and DIN-rail mounting plates. The 70 mm depth means it clears shallow enclosures where a deeper breaker would hit the gland plate or back wall.