What the line gives you
The ABB ACS550-U1-114A-2+B055+L512 is the order code from the ACS550 series, with the +B055 and +L512 suffixes part of the MPN string. Listed in the Motors & Motor Controls / Drives / Motor Drives class, the unit ships as a wall-mountable AC drive package, not a soft starter or DC drive, which is the first question a controls integrator raises when the same panel slot is open.
Sourcing posture
The order code ACS550-U1-114A-2+B055+L512 is specified into the BOM as a complete string; a partial code is not a valid substitute.