What this MCCB brings to the panel
The Siemens SENTRON 3VA1140-6MH36-0AA0 is a 3-pole molded case circuit breaker rated 40 A continuous at 40 °C, with a TM120M thermal-magnetic release tuned for starter protection — meaning it handles motor inrush without nuisance tripping while still clearing a bolted fault. The interrupting ratings climb to 220 kA at 240 V and 154 kA at 415 V, which gives you headroom for high-fault panels where the upstream transformer is close. At 500 V and 690 V it still holds 7.5 kA, so it works across 400 V class and 690 V industrial systems. The 70 mm depth and 76.2 mm width keep it compact on the DIN rail — no surprise for a 3-pole frame at this ampacity.
Thermal derating and real-world current
The 40 A rating holds flat from 40 °C to 50 °C. At 55 °C it derates to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. That's a shallow curve — you lose only 3 A across a 30 °C rise — so in a warm panel near the top of the enclosure you still get nearly full rated current. The maximum power loss is 10.8 W, which is manageable for a 3-pole MCCB at this frame size; no forced cooling needed in a standard IP40 front panel.
Panel fit and integration
Mounts on a standard DIN rail in a 3-pole footprint. The 70 mm depth leaves room for wiring gutters behind the breaker in a 200 mm deep enclosure. The IP40 front protection means it's fine for a clean indoor panel; keep it out of washdown zones unless you add a cover. The TM120M release is factory-set — no field adjustment of the thermal curve, so verify the motor FLA matches the 40 A rating before you install.