The TM-D trip unit combines a thermal element for overload protection and a magnetic element for short-circuit protection — no electronic adjustments, so it's a fit-and-forget choice for standard distribution duty.
Mounts on a backplate in horizontal or vertical orientation. The 81 mm width and 137 mm height fit standard panel layouts; depth is 80 mm. Connection is front-facing via compression lugs or busbars — no rear-access needed, which simplifies wiring in a crowded enclosure. IP40 front face and IK07 impact resistance mean it handles typical panel environments (tools dropped, dust settling) without issue.
In a panel with a transformer or upstream breaker rated higher, you need to verify selectivity — but for most 400 V distribution boards, 36 kA covers the service entrance. Power dissipation is 13.7 W per pole, so at full load the three poles together dissipate about 41 W. That matters for enclosure thermal rise — if you pack several breakers in a small cabinet, factor this into the ventilation or derating calculation. Electrical durability is 20,000 cycles at 440 V at half rated current (In/2), and 10,000 cycles at full rated current (In). Mechanical durability is also 20,000 cycles. For a distribution breaker that sees infrequent switching, that's ample; for a machine that cycles every few minutes, consider a contactor instead.