What the ratings mean for fit
The Siemens 3VA1112-5MH36-0AE0 is a 3-pole IEC molded-case circuit breaker on the 160 A frame, rated 125 A continuous with a TM120M thermal-magnetic trip — the thermal element sized for motor-starting duty (starter protection), not for feeder protection. The magnetic short-circuit pickup is adjustable 5 to 15 times In (625 A to 1875 A), which lets you coordinate with downstream contactor and overload relay let-through. The 55 kA Icu at 415 V AC means it can safely interrupt a fault of that magnitude without upstream fuses or a current-limiting breaker — critical for high-fault panels where the transformer is close. This breaker ships with four factory-installed auxiliary switches (HQ type), so you get position-indication signals for both the main contacts and the trip mechanism without adding external switch blocks. The clamp (box-lug) terminals accept copper or aluminum conductors up to the frame rating — no compression lugs needed for standard panel wiring.
Deployment context
Mounts on a DIN rail or directly to a backplate in a motor control center or distribution panel. The 3VA1 family uses the same accessory platform as the broader Sentron line — shunt trips, undervoltage releases, and rotary-handle mechanisms are shared across frames.