The SENTRON 3VA1225-6GF42-0DA0 is a 4-pole molded case circuit breaker (MCCB) rated for 250 A continuous current with a TM240 thermal-magnetic overcurrent release. It's a line-protection device — meaning it's sized for feeder or main breaker duty, not motor branch-circuit protection where a motor-protective breaker would be the call. The interrupting ratings tell the story: 220 kA at 240 V, 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. That 220 kA at 240 V is the headline number — it handles high-fault scenarios common in large distribution panels or transformer secondaries without needing a current-limiting fuse upstream.
Thermal derating and panel fit
The breaker holds its full 250 A rating from 40 °C up through 50 °C ambient. At 55 °C it derates to 243 A, at 60 °C to 237 A, and at 65 °C to 230 A — hitting 223 A at 70 °C. If the panel ambient runs above 50 °C, size the upstream conductor and bus for the derated value, not the nameplate 250 A. Dimensions are 158 mm high × 140 mm wide × 70 mm deep. That 70 mm depth is shallow enough for most 200 mm deep enclosures with room for wiring gutters. The 140 mm width for a 4-pole frame is standard for this class — verify the mounting footprint matches the existing backpanel drilling if replacing an older frame.
What the undervoltage release means for the circuit
The built-in undervoltage release (UVR) trips the breaker when supply voltage drops below a set threshold — typically 70–35 % of rated control voltage. That's standard for applications where you want automatic disconnection on brownout or loss of control power (safety circuits, emergency-stop chains, or sequencing interlocks). The UVR is factory-fitted, not a field-add accessory, so verify the control voltage matches your panel's auxiliary supply before wiring. Rated insulation voltage is 800 V, and maximum power loss is 59.5 W — factor that into enclosure ventilation if the panel is densely populated.