Sizing and what the catalog figure actually constrains
The ACS355-03U-31A0-4+J400 order code carries 31A0 as the current class at 2.27 kgs, per the spec row. The 15 kW figure names the motor size this 31 A / 400 V frame typically matches on a four-pole induction motor load.
Where the J400 plus-code sits in the ACS catalog
The +J400 suffix is part of the ACS355-03U-31A0-4+J400 order string as written in the spec row; it modifies the base ACS355-03U-31A0-4 body and must be ordered as one string with the base code.
Commissioning and EMC posture
On a 400 V drive like the ACS355-03U-31A0-4+J400, the application-side watchpoints are motor cable length, grounding scheme, and output filtering. Long motor cable runs risk reflected-wave overvoltage at the motor terminals; an output filter sized to the 31 A class belongs in the BOM with the drive, not retrofitted later. EMC-wise, line-side filtering and PE bonding at the cabinet gland plate keep conducted emissions contained.