SENTRON 3VA1112-5MH32-0BA0 — starter-protection MCCB with undervoltage release
The Siemens SENTRON 3VA1112-5MH32-0BA0 is a 3-pole molded case circuit breaker (MCCB) designed for starter protection — meaning it's built to sit ahead of a motor contactor and handle the high inrush and short-circuit stress a motor branch can throw at it. Rated 125 A at 40 °C with a TM120M thermal-magnetic release, it carries a 187 kA interrupting rating at 240 V, dropping to 121 kA at 415 V and 75.6 kA at 440 V, so it handles substantial fault energy in low-voltage distribution.
What the ratings mean for fit
The 125 A rating holds flat from 40 °C through 50 °C, then derates gradually to 114 A at 70 °C — a thermal curve that matches the SENTRON family and keeps the breaker usable in warm enclosures without oversizing. The 800 V rated insulation voltage (Ui) is standard for this class and confirms it can sit on a 690 V line with margin. The undervoltage release (UVR) integrated into this order code means the breaker trips if control voltage drops below a threshold — common in safety circuits where a machine must stop on power loss. No communication function, no ground-fault monitoring; this is a straight power breaker with a UVR accessory built in. Dimensions are 130 mm height, 76.2 mm width, 70 mm depth — a 3-pole footprint that fits standard SENTRON 3VA mounting plates and panel cutouts. The 30.6 W maximum power loss at full load matters for thermal budgeting inside a sealed enclosure.
Deployment context — panel and motor branch
This MCCB snaps onto a DIN rail or mounts to a backplate in a low-voltage switchboard or motor control center. It's sized for motor starter protection, so it pairs with a contactor and overload relay upstream of a pump, fan, or compressor. The wide operating temperature range (-25 °C to 70 °C) and storage range (-40 °C to 80 °C) make it suitable for unheated enclosures in temperate climates.