The Siemens SENTRON 3VA1112-1AA36-0CA0 is a 3-pole switch disconnector in an MCCB-style frame, rated for 125 A continuous without overload or short-circuit protection. It is designed for applications where you need a manual disconnect with visible isolation, not a circuit breaker — think load-break switch duty ahead of a VFD or as a panel main isolator where the upstream device handles fault clearing. The 125 A rating holds flat across the full operating temperature range from 40 °C to 70 °C, so no derating curve to chase in a warm enclosure.
What the ratings mean for fit
Rated 690 V AC and 500 V DC, so it handles standard 400 V three-phase systems with headroom and can switch DC loads up to 500 V — useful for battery banks or DC bus isolation. The 800 V rated insulation voltage (Ui) confirms it's built for 690 V line-to-line systems without creepage concerns. The undervoltage release (UVR) is factory-fitted for 120-127 V AC 50/60 Hz; if the control voltage drops, the switch trips open. That's a common safety interlock for emergency-stop circuits or undervoltage protection on motor feeders. No auxiliary contacts are included, so if you need status feedback to a PLC, you'll add a separate auxiliary switch block. Mechanical life is rated at 15,000 operating cycles — typical for a switch disconnector in this frame class. For daily switching in a production line, that's years of service; for frequent cycling (multiple times per shift), consider a contactor instead. The IP40 front protection means it's suitable for clean indoor panel environments; no washdown rating here.
Panel integration and wiring
Footprint is 76.2 mm wide, 130 mm tall, 70 mm deep — a standard 3-pole MCCB cutout. Front terminal connections with clamp-type terminals accept lug or cable. The 38 W maximum power loss at rated current matters for thermal management in a densely packed panel; account for that heat when sizing ventilation or spacing between devices. The design accepts an optional motor drive for remote switching, and the UVR coil draw is included in the loss figure.