What it is and where it sits on the BOM
The ABB ACS550-01-045A-4 is a member of the ACS550 series low-voltage AC drive family, catalogued under Motors & Motor Controls › Drives › Motor Drives, and the order code on the line card is ACS550-01-045A-4.
Cross-shop notes against same-family peers
Three same-family peers appear on the cross-shop list: ACS550-U1-096A-4 at 19.96 kgs, and ACH580-01-014A-4 and ACH580-01-023A-4 at 6.80 kgs each. The split is series, not size — the U1-096A-4 is an ACS550-U1 (UL-listed) frame at roughly double the current class, while the ACH580 entries are a different, newer platform. That distinction matters for the panel-rework question — a cabinet laid out for ACS550-U1-096A-4 will not accept a -01-045A-4 without re-checking footprint, current class and the U1 versus -01 enclosure rating, so the answer to a drop-in swap is negative on dimensional and ratings grounds, not on connector-pinout grounds.