The Siemens 3VA1112-1AA32-0AC0 is a SENTRON 3VA1 switch disconnector in an MCCB-style housing — 3-pole, rated for a flat 125 A continuous from 40 °C all the way up to 70 °C, so no derating curve to chase for most panel ambient conditions. Critical distinction: this is a switch disconnector only — no overload protection, no short-circuit protection built in. The SD100 designation on the description flags it as a pure isolating and switching device. If you need overcurrent protection, you want the 3VA1112-5EE32-0AA0 molded case circuit breaker variant instead. It carries 2 HQ auxiliary switches (form C, CO contacts) for status feedback, wired via front terminals with busbar connection for the main circuit.
Maximum power loss is 38 W — modest for a 125 A switch, but worth factoring into enclosure thermal calculations if you're packing several of these side-by-side.
Front IP40 protection suits clean indoor panels. Main circuit connects via busbar with front terminals — typical for panelboard or distribution block feed. Motor drive is optional if remote switching is needed later. Mechanical life is 15,000 operating cycles — adequate for isolation duty.