What the order code points to
ACS550-01-038A-4+B055 is the ABB ACS550-01 AC drive with the +B055 option suffix appended, catalogued under Motor Drives at 5.90 kgs chassis weight.
Where this drive class is applied
ACS550-frame drives are general-purpose industrial AC drives sized for fans, pumps, conveyors, and constant-torque loads where sensorless vector control and a built-in Modbus interface are enough. The +B055 suffix is an application-specific option bundle layered on the base drive; matching it on a replacement BOM keeps the panel wiring and parameter map consistent.
Cross-shop notes against the ACH580 and ACS380 peers
ACH580-01-014A-4 and ACH580-01-023A-4 are catalogued in the same Motor Drives slot at 6.80 kgs, and ACS380-040C-032A-4+K475 sits at 5.90 kgs. The ACH580 is a separate ABB platform, not a same-frame substitute for the ACS550-01-038A-4+B055.
Sourcing posture
Quoted to order against an RFQ; specify the full suffix string ACS550-01-038A-4+B055 on the BOM line so the option bundle is not lost in procurement.