What the TMF trip unit means for fit
The XT2LU3040ADD000XXX: The TMF designation indicates a fixed thermal-magnetic trip curve — the thermal element handles sustained overloads (inverse-time), and the magnetic element clears short-circuits instantaneously. The 40-400 A range covers a wide band of motor and feeder protection; the fixed curve means no interchangeable trip plugs or electronic adjustments, so verify the installed setting matches the load's full-load ampere rating. In a 3-pole configuration, it switches all three phases simultaneously, which is standard for three-phase branch circuits and motor disconnects.