What you're sourcing
The ABB ACS550-PD-059A-4+B055 is the PD-form-factor variant in the ACS550 series, sitting in the Motor Drives class alongside the rest of the ACS550 general-purpose drive family. Mass on the nameplate is 36.29 kg, which puts it firmly in the cabinet-floor handling bracket rather than the DIN-rail bracket — plan the lift and the panel load before the crate arrives. Branding carries as ABB on this listing, which matters when you cross-reference against earlier ASEA BROWN BOVERI documentation in legacy BOMs.
Where the PD suffix sits in the ACS550 family
The closest same-current sibling, ACS550-U1-059A-4+B055, lists the same 36.29 kg figure and the same 059A-4 rating class, with a different enclosure code. That means the U1 and PD variants share the rating and the mass, so the swap question is the enclosure footprint and the gland plate layout, not the drive electronics rating — confirm the cabinet cut-out against the PD drawing before specifying, since the suffix change is mechanical, not electrical.