What the order code resolves to
The ACS550-U1-031A-4: At 14.47 kg, the unit is a one-person lift onto a wall bracket inside a control room — the practical concern at this mass is mounting hardware and torque on the wall anchors, not shipping weight. If the line is down and the spare is in stores, plan on one technician to set it and a second to land the power leads; the output wiring side is the heavier work.
What the headline ratings decide
The output rating of 31 A at 380-480 VAC, 50/60 Hz is the figure the application engineer works against: it sets the upper limit for constant-torque loads on a 15 kW motor, and it is also the number the upstream breaker and the output cable sizing have to clear. Below the output figure, the ACS550 family is a general-purpose sensorless vector drive class — sized for fans, pumps, conveyors and similar industrial loads at the 15 kW node, not for high-inertia or vertical-axis applications without braking consideration. Cable-side planning for a 480 V drive is the next decision after the rating: longer motor leads call for a dV/dt or sine filter, while shorter runs land direct.