The ABB ACS550-U1-012A-4+B055 on the BOM line
The ABB ACS550-U1-012A-4+B055 is an AC drive from the ACS550 family, listed in the Motor Drives line at a shipping weight of 7.26 kgs. The +B055 suffix in the order string denotes the factory option bundle applied at build; it sits inside the standard ACS550-U1 frame designation rather than identifying a separate product family.
Where this class of drive is used
AC drives in this class are specified for variable-speed control of AC induction motors — fans, pumps, conveyors, mixers — where soft-start, ramp profiles, and adjustable acceleration replace across-the-line contactor control. At 7.26 kgs, this wall-mount drive lands inside a VFD cabinet section with clearance for input fusing and motor-cable glanding the panel builder expects.
Sourcing posture for the ACS550-U1-012A-4+B055
For panels already designed around the legacy ACS550 generation, keeping the ACS550-U1-012A-4+B055 on the BOM preserves the original wiring, parameter set, and spare-parts commonality; an ACH580 swap belongs on a re-engineered panel, not as a field-service alternate.