What This Part Is and What It Does
The Siemens 3VA1112-1AA36-0DH0 is a SENTRON 3VA1 switch disconnector in an MCCB-style housing — IEC frame 160, three poles, rated for 125 A continuous current (Iu). It is a pure disconnect: no overload or short-circuit protection built in, so it functions as a manual load-break switch for isolation and switching of circuits where the upstream protection handles the fault clearing. Rated insulation voltage is 800 V (Ui), with maximum operational voltage 690 V AC and 500 V DC. The front terminal connection accepts cable lugs, and the IP40 front protection keeps dust out of the panel cutout.
Undervoltage Release and Auxiliary Contacts
This variant ships with an undervoltage release (UVR) coil rated 208-230 V AC 50/60 Hz — the UVR trips the disconnector when supply voltage drops below the dropout threshold, preventing automatic reclosure after a power loss. No leading contact on the UVR, so the coil must be energized before the main contacts close. Auxiliary contact configuration is 2 form-C auxiliary switches plus 1 form-C trip alarm switch, all HQ (high-utilization) rated. That gives three CO contacts total for status feedback to a PLC or indicator lamp. The trip alarm switch changes state only on a UVR-triggered opening, not on manual operation — useful for distinguishing a fault trip from a normal shutdown.
Dimensions and Panel Fit
Footprint is 76.2 mm wide (3-inch grid compatible), 130 mm tall, 70 mm deep — same mechanical envelope as the 3VA1 MCCB line. Mounts on a DIN rail or directly to a backplate via the screw terminals. The front terminals are accessible with the panel door closed, so wiring checks don't require removing the device.