The subject of the contract is the expansion of the 400/110 kV Płock substation to connect new facilities to the National Power System (KSE). The detailed scope of work is defined in Part II of the SWZ (Functional-Utility Programme). The works are classified under CPV code 45000000-7 (Construction works). Equivalent solutions to those described by the contracting authority are permitted, provided the contractor demonstrates they meet the specified requirements.