It provides LI protection — thermal overload (L) and magnetic short-circuit (I) — for distribution applications in AC or DC networks. Rated 125 A at 50 °C, it fits a 3-pole 3D breaker with fixed mounting. The instantaneous pickup is fixed at 1250 A (10× In), and the long-time pickup is adjustable from 0.7 to 1× In. That means you can dial the overload threshold down to 87.5 A if the load requires it, without changing the trip unit. Rated operational voltage is 690 V AC (50/60 Hz) and 750 V DC, so it handles standard 480Y/277 V and 600 V panels with headroom, and can be used in DC bus applications up to 750 V.
This is a trip unit, not a complete breaker — it installs into a ComPacT NSX160 or NSX250 fixed-mount circuit breaker. The TM-D unit has no earth-leakage protection built in. If you need ground-fault detection, you'll need a separate Vigi module or an electronic trip unit with that function. The 3D pole configuration protects all three phases; the neutral is unprotected unless you add a 4-pole breaker.
No second-source cross-reference exists within the same frame — the TM-D is the standard thermal-magnetic option for NSX160/250.