OREANDA-NEWS. The Nippon Telegraph and Telephone Corporation, has published the Technical Requirements (TR) for "High-Voltage DC (HVDC) power supply system" that is considered as the next-generation power supply system, by summarizing technical specifications for introducing them to telecommunication and data-center buildings in NTT group.

The document, titled "Technical Requirements for High-voltage DC Power Supply Interfaces "., is based on standards set by the International Telecommunications Union - Telecommunication Standardization Sector (ITU-T).

By opening to the public to this TR, NTT would like to widely stimulate use of HVDC in the information & communication fields. In addition, NTT is continuously making our efforts to tackling energy conservation throughout the ICT fields.

The amount of energy consumed in the ICT field has been increasing year by year, and that has been accompanied by an increase in the emission of greenhouse gases, which has become a worldwide issue to be concerned. According to "SMART 2020: Enabling the low carbon economy in the information age", the greenhouse gas emissions in ICT amounted to 0.83 billion tons of CO2 in 2007, or 2% of the world total, but that amount is estimated to nearly double to 1.43 billion tons of CO2 by 2020.

Against that circumstance, the NTT Group which is one of the world largest companies to manage a large number of telecommunication and data-center buildings has been tackling in energy conservation measures under a policy: the Total Power Revolution (TPR), and focusing on the development and introduction of high-voltage DC power supply systems as a future measure.

HVDC supply systems are attracting attention as the next-generation system because they have fewer voltage conversion steps than an AC system, so an increase in reliability and a reduction in power loss can be expected. Moreover, increasing the voltage creates advantages such as enabling use of thinner power cable that reduces construction costs (materials and labor) and energy efficiency through improved air flow below the raised flooring of machine rooms in telecommunication or data-center buildings.

As an ability and energy usage of ICT equipment become increase, worldwide attention is being focused on HVDC power supply systems because they offer both high reliability and energy efficiency. Due to these advantages, standardization work in ITU-T has become active, and NTT energy and environmental systems laboratories have been leading the International standardization activities. As results, two international Recommendations have been established (ITU-T L.1200, "Direct current power feeding interface up to 400 V at the input to telecommunication and ICT equipment" in May, 2012 and ITU-T L.1201, "Configuration of Direct Current Power Supply Systems Up to 400 V" in March, 2014).

The NTT Group has led the way in introducing HVDC power supply systems, and as a step toward expansion to full-scale introduction of next-generation systems to NTT Group telecommunication and data-center buildings, we have summarized and published technical requirements for connection of HVDC power supply systems and ICT equipment in telecommunication or data-center buildings.