What's on the line
The ABB ACS550-01-015A-4 is an AC drive in the Motors & Motor Controls / Drives / Motor Drives class, listed at 9.00 kgs — that's the only physical anchor I can ground from the record, so panel space, mounting kit selection and handling all flow from that figure. The order code is the only thing on the spec row that drives a like-for-like swap, so every substitution question has to start there. With a part on the bench at this weight class, the first thing I check isn't a fault code — it's the panel footprint and the gland/conduit arrangement around the drive. 9.00 kgs tells me this is a two-person lift on a ladder and a unit that wants a real backplate, not a thin wall bracket. Get that wrong and the heatsink can't dump properly; that's where the premature cap-aging cases start.
Where the comparison line actually matters
ACH550-UH-023A-4 is the HVAC-flavored cousin at 11.34 kgs — close on weight but a different firmware target, so BACnet/Modbus commissioning macros and PID defaults differ. If the BOM line is a fan/pump application, the AHJ is going to want to see why the 'UH' variant is or isn't on the drawing, not why the 015A-4 is.
Sourcing posture
For an MRO planner looking at a down line, order the exact order code on the failed unit: ACS550-01-015A-4 at 9.00 kgs. Verify the parameter set from the backup file before energizing the replacement.