What the 40 A TM-D rating means for your panel
The C11E3TM040B is a 3-pole ComPact NSXm MCCB with a 40 A thermal-magnetic TM-D trip unit. That 40 A is rated at 40 °C ambient — so in a warm panel you're not derating from a 50 °C fantasy number. The 9-module pitch (81 mm wide, 137 mm tall, 80 mm deep) fits standard DIN-rail enclosures with a 35 mm connection pitch when using spreaders; 27 mm without. Front connections top and bottom accept compression lugs or busbars, so it's a straightforward swap into an existing MCC bucket or panelboard.
What else the spec sheet tells you
Pollution degree 3, overvoltage category III, IP40 enclosure (IK07 impact). Electrical durability runs 20,000 cycles at 440 V at In/2, 10,000 cycles at In, and 5,000 at 690 V In. Power dissipation is 3.8 W per pole — about 11.4 W total at full load, so factor that into your enclosure thermal calcs. If you need ground-fault, you'd add a separate Vigi module or specify the earth-leakage version. Operating altitude: 2000 m without derating, 5000 m with derating. Relative humidity 0–95 %. Standard network frequency 50/60 Hz.