What it is
The ABB ACS800-U4-0050-5+P901 is an AC cabinet-format drive from the ACS800-U4 series, carrying the +P901 option code suffix that defines the as-shipped configuration of this specific order string. It sits in the Motor Drives class — industrial low-voltage AC drives intended for cabinet integration rather than wall-mount — so the panel-builder specifies enclosure space, cooling path, and cable entry around the unit rather than treating it as a standalone appliance. Mass is listed at 15.43 kg, which puts the unit in single-person lift territory for installation but well above what a typical DIN-rail compartment can carry — it expects a back-panel or cabinet-frame mount, not a snap-on rail.
Where it fits in the panel
As an ACS800-U4-0050-5+P901 the drive is specified into a cabinet MCC section with line reactors, braking choppers, and I/O wiring landed to the drive's control terminals — the U4 cabinet format is built for that integration rather than for retrofit on a small machine skid. The +P901 option code is the part of the order string that fixes which factory-fit options ship with the unit; specifying the wrong +P901 variant is the most common cause of a unit arriving without the I/O extension or encoder board the panel was designed around, so the full code including the suffix needs to be carried on the BOM line and on any replacement RFQ.
What the MRO keeper needs to know
The order code on the shelf label has to read ACS800-U4-0050-5+P901 in full — including the +P901 suffix — because dropping the suffix changes the factory configuration even though it reads as the same base drive on a glance; that's the kind of partial-match SKU that ends up on the wrong shelf and gets pulled for the wrong job.