What this MCCB is and what it does
The Siemens SENTRON 3VA1225-6GE42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated at 250 A continuous, with a TM220 thermal-magnetic trip unit. It's designed for line protection in distribution panels — the TM220 gives you a fixed thermal curve for overloads and a magnetic trip for short circuits, no electronic adjustments. The 250 A rating holds from 40 °C up to 50 °C before derating starts (243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, 223 A at 70 °C), so in a warm enclosure you still get full ampacity up to 50 °C.
Breaking capacity — what the numbers mean for your fault duty
This breaker's interrupting rating varies sharply with system voltage: 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. For a 480 V panel (common in North America), the relevant figure is the 440 V rating at 75.6 kA — that's the closest standard voltage. At 690 V the 17 kA figure still covers most industrial fault duties, but verify your available fault current against that number. The rated insulation voltage is 800 V, so the breaker is built for 690 V systems without derating the insulation.
Panel fit and integration
Dimensions are 158 mm high, 140 mm wide, 70 mm deep. Front face carries IP40 protection — fine for a closed panel, not for washdown. The 4-pole format handles three-phase-plus-neutral or three-phase-plus-switched-neutral configurations. Power loss at rated current is 57 W, so factor that into your enclosure thermal calculation. No undervoltage release, no communication function, no ground-fault monitoring on this variant — it's a straight thermal-magnetic line-protection breaker.