The Siemens 3VA1112-1AA32-0DH0 is a SENTRON 3VA1 switch disconnector in an IEC frame 160, 3-pole SD100 design, rated for 125 A continuous current without overload or short-circuit protection elements built in. It functions as a manually operated load-break switch for isolation and switching in distribution panels — think of it as the disconnect ahead of a motor feeder or a branch circuit where you need visible isolation but the overcurrent protection lives downstream in the MCCB or fuse. The 125 A rating on a 160 A frame gives thermal headroom for continuous loads at elevated ambient temperatures up to 70 °C.
Rated continuous current Iu of 125 A on the 160 A frame means this switch disconnector carries full load continuously without derating at 40 °C; above that, the thermal curve applies. The max rated operational voltage of 690 V AC 50/60 Hz covers 400 V and 480 V systems with margin; the DC rating of 500 V makes it usable in 250 V or 400 V DC bus applications common in data-center or solar combiner panels. When control voltage drops below about 170 V, the UVR trips the switch open. This is standard for safety interlocks or emergency-stop chains where a loss of control power must drop the load — common on conveyor lines or press feeders. The UVR has no leading contact, so it does not provide early break; the main contacts carry the full interruption. That gives three independent status signals: switch open/closed, switch open/closed (redundant or for two different loads), and a separate trip alarm that only changes state when the UVR or a manual trip opens the switch under fault. Useful for PLC inputs or status lamps without adding external relay blocks.
Mounts on a DIN rail via the integrated clip; the 76.2 mm width (roughly 4.5 modular units) and 70 mm depth fit standard 200 mm deep enclosures. Main circuit connection is busbar connection with front terminals — the busbar stabs insert from the front, so plan busbar routing behind the switch. The UVR and auxiliary switches are factory-fitted; no field wiring of internal coils. The nut keeper kit (included per the description) retains the busbar mounting nuts during maintenance.