SENTRON 3VA1 MCCB — 125 A, TM240, Undervoltage Release
The Siemens 3VA1112-4EF32-0BA0 is a SENTRON-series 3-pole molded case circuit breaker (MCCB) rated for line-protection duty, carrying a continuous current of 125 A at 40 °C ambient and a TM240 thermal-magnetic trip unit. The TM240 designation means the thermal element is fixed at 125 A (the frame rating) and the magnetic short-circuit pickup is factory-set at 240 A — roughly 8x In for this frame, typical for motor or distribution feeder protection where you want inrush ride-through. Breaking capacity is the headline spec here: 121 kA at 240 V, dropping to 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V. That 75.6 kA at 415 V puts it squarely in high-fault-current territory — think transformer secondaries or large motor control centers where the available fault current is well above 50 kA. At 690 V the 11.9 kA rating still clears most industrial distribution faults, but verify your point-of-fault current against the 11.9 kA ceiling. The breaker includes a factory-fitted undervoltage release (UVR), designated as an undervoltage release (UVR) auxiliary release. This means the breaker trips if the control voltage drops below a set threshold — standard for safety circuits where loss of control power must open the main disconnect. No ground-fault monitoring or communication module on this variant; it's a straight thermal-magnetic line-protection device with UVR.
Thermal Derating & Panel Fit
Full 125 A rating holds from 40 °C through 50 °C ambient. Above that it derates linearly: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. If your panel ambient runs hot — say, a non-ventilated enclosure near a furnace line — factor in the 114 A ceiling at 70 °C rather than the 125 A nameplate. Maximum power dissipation is 30.6 W, which matters for enclosure thermal calculations in a packed cabinet. Physical footprint: 130 mm height, 76.2 mm width, 70 mm depth. That 70 mm depth is shallow enough to fit most standard distribution panels without a deep enclosure — common for retrofit into existing switchboards where depth is constrained. The 3-pole body occupies three 18 mm module spaces on a DIN rail or direct-mount plate. Rated insulation voltage is 800 V, so the breaker is suitable for 690 V systems with margin. Operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C. No trip indicator on this variant — you'll need to check the handle position or add an auxiliary switch for remote status.