The present document contains requirements and measurements methods for the physical interface "A3" that is situated between the power supply system(s) and the power consuming ICT equipment: - the nominal voltage at power interface "A3" of ICT equipment defined in the present document is DC voltage up to 400 V; - the output performance of the power equipment including the cable network at the interface "A3"; - the input of the ICT equipment connected to interface "A3". The DC power can be supplied by a DC output power system e.g. via on-grid AC rectifiers, from DC/DC converters in solar systems, fuel cells, standby generators including a battery backup. The present document aims at providing compatibility at interface "A3" between the power supply equipment and different ICT equipment (including/monitoring, cooling system, etc.) connected to the same power supply.