What the BOM line actually carries
The ACS800-U1-0006-5+L503+N661+P901 is a configured ACS800-U1 wall-mount AC drive, size code 0006, with the +L503, +N661 and +P901 option suffixes baked into the factory build rather than added in the field. Listed weight is 7.53 kgs, which keeps the U1 frame in single-person lift territory for panel mounting on a reinforced backplate.
Reading the suffix string
The four + codes are where the procurement risk lives on this build: +L503, +N661 and +P901 are factory-fitted options that change the I/O, feedback or documentation package the cabinet builder specified around. Specifying against the bare ACS800-U1-0006-5 base and retrofitting these options in the field is not the same order code and will not match the original nameplate.
Frame continuity against the ACS880 generation
ABB's current-generation wall-mount successor in this rating band is the ACS880-01 family. The 7A6 frame (ACS880-01-07A6-5) sits at 6.35 kgs, the 021A frame (ACS880-01-021A-5) at 7.71 kgs, and the 052A frame (ACS880-01-052A-5) at 9.07 kgs — same U1-style cabinet footprint, adjacent current ratings, so the panel cutout, gland plate and cooling envelope carry across without rework.