What the order code is buying
The ABB ACS800-U1-0025-5+N660+P901 is a wall-mount single-drive AC drive from the ACS800-U1 series, factory-configured with the +N660 and +P901 option codes stamped into the same part string. The base code locates the unit on the ACS800-U1 wall-mount line; the trailing +N660 and +P901 are the option suffixes that define the as-shipped build, and they have to match the purchase order line-for-line when a replacement is being specified into an existing panel. Mass is 14.06 kg, so the drive lands on the wall-mount handling class — a single service tech can position it on a backplate, but the bracket and the panel itself should be sized for that load before the unit is hung. Anything lighter than this in the class is normally a frame size down, and the weight figure is a useful sanity check that the correct frame has been quoted.
Where it fits in a panel
It is catalogued as a Motor Drive under Motors & Motor Controls, which puts it in the complete-drive category rather than the converter-module or regen-supply class. In the panel that means line filter, line reactor where required, and motor cable termination are all expected to be external to the unit — the drive itself is the enclosed wall-mount package, not a sub-assembly to be integrated into a larger cubicle.
Sizing and cross-reference to the ACS880-01 generation
The ACS880-01 wall-mount series is the factory successor class. The closest peer on record is the ACS880-01-040A-5 at 18.14 kg, same single-drive wall-mount form factor and one frame size up by mass. The other two peers, ACS880-01-034A-5 at 10.43 kg and ACS880-01-027A-5 at 10.41 kg, sit one to two frames down on mass and match the original more closely on weight.