The Siemens 3VA1112-1AA36-0AF0 is a SENTRON switch disconnector in the 3VA1 IEC frame 160 platform — a three-pole device rated for 125 A continuous current (Iu) that provides visible isolation of a circuit but carries no overload or short-circuit protection elements. It is designed strictly as a load-break disconnect for maintenance and safety isolation, not as a circuit breaker.
Rated continuous current Iu is 125 A — this is the maximum current the disconnect can carry continuously without exceeding its thermal limits. The maximum power loss at that load is 38 W, so panel ventilation matters if multiple units are ganged. Rated insulation voltage Ui is 800 V, and the maximum operational voltage is 690 V AC (50/60 Hz) or 500 V DC. Short-time withstand current is rated at 2 kA for both 0.5 s and 1 s durations. This tells you the disconnect can survive a fault current up to 2 kA for up to one second without welding its contacts — but it will not interrupt that fault. Upstream protection (a fuse or circuit breaker) must clear the fault before the disconnect's thermal limit is reached. The mechanical endurance is 15,000 operating cycles, which is typical for a panel disconnect that sees daily switching but not continuous motor starting.
The 3VA1112-1AA36-0AF0 mounts on a DIN rail via the standard 3VA frame footprint: 70 mm deep, 76.2 mm wide (3 inches), 130 mm tall. Front terminal connection for the main circuit — clamp-type terminals accept copper or aluminum conductors. The auxiliary contact block is factory-integrated, so no add-on module occupies adjacent DIN space. An optional motor drive can be added for remote switching (product extension optional).
The closest functional peer in the same frame is the 3VA1110-5EF32-0AM0, which is a full molded-case circuit breaker with thermal-magnetic overcurrent protection (TM240), rated 100 A at 40 °C, and carries a much higher interrupting capacity (187 kA at 240 V AC). By contrast, the 3VA1112-1AA36-0AF0 is a switch disconnector only — no overcurrent trip, no fault interruption capability, and a lower short-time withstand (2 kA). The physical footprint is identical (same 70×76.2×130 mm envelope), so a panel designed for the breaker can accept the disconnect without rewiring the bus bars or DIN-rail position. The decision between them is purely functional: if the circuit already has upstream overcurrent protection and you only need a local disconnect, the 3VA1112-1AA36-0AF0 is the correct choice; if you need integrated branch-circuit protection, use the 3VA1110-5EF32-0AM0.