Open Electronic Tender Below The Limits For The Conclusion Of A Contract For The Provision Of Maintenance Services - Technical Support And Repair Of: 1) Generator Pairs (H/Z), 2) Medium Voltage Substations (M/S M.T.) And 3) Uninterruptible Power Systems (Ups), Which Are Installed In Buildings Housing The Services Of The Central Administration/Competence Of The Administration Of E-Efka In Attica (Fpy 38/26)