The ACS800-U1-0050-5+L503+P901: The +L503 and +P901 suffixes are factory-installed option modules – likely a fieldbus adapter or I/O expansion – so this drive is pre-configured for a specific application. If you're replacing one, match the option codes on the nameplate; a bare ACS800-U1-0050-5 won't drop in without those modules.
Sourcing Decision – What to Expect
Because this is an EOL part with no factory successor, every unit is sourced from the aftermarket. Expect to supply the full order code including option suffixes so we can match the exact configuration. No rewiring or re-engineering if you stay with the same part number.