The purpose of this part of IEC 62257 is to specify the general requirements for the design and the implementation of the interface equipment within the user’s installation which connects to a microgrid or the generating part of a standalone system. This part of IEC 62257-9 applies to a simplified user's interfaces (distribution board) in electrical installations with maximum power of 500 VA in Decentralized Rural Electrification Systems (DRES). NOTE For installations above 500 VA in decentralized electrification systems, IEC 62257-5 applies. This part of IEC 62257-9 applies to an interface equipment within the user’s installation and which connects the user's installation to: • 230 V a.c. or 120 V a.c. microgrid, • the generating part – a.c. or d.c. - of a stand-alone installation. This equipment provides protection, isolation, and distribution functions.