The Siemens 3VA1112-5MH36-0AF0 is a 3-pole IEC frame 160 circuit breaker rated 125 A with a 55 kA breaking capacity (Icu) at 415 V, placing it in breaking capacity class M. This is a motor-starting protection variant (TM120M, AM) — it provides short-circuit protection with an adjustable instantaneous trip (Ii) from 5 to 15 times In, but no overload protection, so it pairs with a separate overload relay for motor branch circuits. The unit ships with clamp terminals, one auxiliary switch HQ, and one trip alarm switch HQ.
What the Ratings Mean for Fit
The 55 kA Icu at 415 V means this breaker can safely interrupt a fault current up to 55 kA without failing — critical for installations with high available fault current, such as large industrial switchboards or transformer secondaries. The adjustable instantaneous trip (5–15 x In) lets you set the magnetic trip threshold between 625 A and 1875 A, which you coordinate with the downstream motor's locked-rotor current and upstream protective device. Because it omits overload protection, you must add a separate thermal overload relay (e.g., Siemens 3RU2 series) in the motor starter assembly.
Panel Integration
Clamp terminals accept conductors without lugging, which speeds panel wiring. The 3VA1 frame mounts on a DIN rail or can be screw-mounted to a backplate; the auxiliary switch and trip alarm switch occupy the left-side accessory slot, so factor that into your enclosure fill calculation.