scope:

This Recommendation defines solutions for progressive migration of information and communication technology (ICT) sites (telecommunication and data centres) to up to 400 V direct current (400 VDC) distribution and direct use of up to 400 VDC powering ICT equipment from 400 VDC sources. The Recommendation also defines different major use case options and migration scenarios, such as:

- migration to an up to 400 VDC of telecommunication site power solution;

- migration to an up to 400 VDC of data centre power solution;

- migration with up to 400 VDC power transfer between existing −48 V centralized sources to high power density −48 V equipment, such as routers;

- integration of up to 400 VDC remote powering;

- combined architecture with up to 400 VDC and AC sources and distributions possibly using hybrid power interfaces on ICT equipment.

For each of these, this Recommendation describes many possible options and characteristics, such as:

- migration architecture with up to 400 VDC/−48 V conversion to power existing −48 V equipment using existing −48 V room distribution; 

- conditions for tripping overcurrent protection devices without −48 V batteries;

- migration architecture with up to 400 VDC/AC inverter as an alternative to the AC UPS to power existing AC equipment;

- use of local up to 400 VDC for remote powering of ICT equipment;

- coupling up to 400 VDC systems to a local REN source or to a DC microgrid;

- possibility of conversion between battery and up to 400 VDC distribution, e.g., for long power distribution or short-circuit current or battery technology (e.g., lithium-ion).

This Recommendation also gives a saving assessment frame reference to define the best migration scenario and its steps by considering energy, resource, environmental impact and cost savings based on functional aspects such as modularity, flexibility, reliability, efficiency and distribution losses, as well as maintenance evolution when migrating from −48 V or alternating current (AC) to up to 400 VDC solutions. This also includes consideration of load architecture evolution dependent on use cases (e.g., telecommunication site, data centres).