SG5 is responsible for studying ICT environmental aspects on electromagnetic
phenomena and climate change. In addition, SG5 has been appointed as a lead
Study Group to advance the work on ICT and Climate Change.
Along with the wide spread use of the Internet, a great deal of ICT
equipment, such as routers, servers, and switches, has been installed in
telecommunication centres to enable high-speed and large-scale broadband
services. A DC power feeding system is commonly used inside a telecommunication
centre or a Data centre because the power efficiency is higher than that for an
AC power feeding system due fewer converters.
The power consumption per rack of conventional (legacy-type) equipment such
as exchanges or transmission devices is about 2 kW. On the other hand, that for
ICT equipment, such as routers and servers has reached over 7 kW. Therefore, the
feeding current is over a hundred amperes when we use a 48Vdc power feeding
system to supply power to ICT equipment. Moreover, the feeding cable must have
sufficient capacity for the current, so the diameter of the cable becomes large.
This situation has several disadvantages such as length limitation, voltage drop
caused by cable resistance, heavy weight, and inflexibility.
However, power feeding systems in telecommunication centers, for example, are
not specified in International standards. Along with the increase in energy
consumption of the devices, energy efficiency of the feeding system is also an
important factor in reducing the CO2 produced by ICT systems. Moreover, these
disadvantages may lead to the use of many materials, such as copper and
plastics, and may require significant consumption of energy to construct those
Therefore, it is important to consider not only the energy consumption of the
telecommunication devices, but also the validity of the energy supply to the
This work directly and indirectly contributes to a reduction in the
environmental impact of ICTs, e.g., CO2 and material use.
This Question mainly focuses on the energy efficiency of the power feeding
systems that are used in telecommunication networks or customer buildings. To
achieve higher energy efficiency, this Question will prepare methodologies for
evaluating the energy efficiency of power feeding systems including AC and DC
systems, specifications on power feeding systems, safety issues for devices and
service personnel, and methods for constructing an earthing and bonding system.
One of the key issues is characterization of a Higher Voltage DC power feeding
system, the voltage for which is around 400 V. The Higher Voltage DC power
feeding system is a topic of great interest around the world because of its
ability to improve the energy efficiency of the power feeding system. The
standardization of its specifications is very important to promote the
development of the system and improve the validity of the energy supply to the
Study items to be considered include, but are not limited to:
The work under this question could provide the basis for L-series Recommendations on power feeding systems.
- Specification of the power feeding systems, especially for the Higher
Voltage DC systems
- Nominal voltage, operation voltage range, abnormal voltage range under
fault condition, etc.
- Safety criteria and requirements for service personnel and equipment.
1) Protection (blocking) devices such as fuses, breakers, etc.
2) Basic principle for safety and working practices,
3) Requirements and criteria for protecting service personnel and
apparatuses under normal and abnormal operating conditions.
- System configuration and specification of the power feeding system
1) Earthing and bonding system of the power feeding system
2) Cable distribution method, basic concept (or architecture) of the power
- Methodologies for evaluating various power feeding systems such as the
conventional DC system, AC system provided by commercial power networks, and
Higher Voltage DC system
1) Methods for evaluating performance of the system
2) Calculation (or estimation) method for obtaining environmental effect of
the system, validity of the energy supply system to the ICT equipment, etc
Tasks include, but are not limited to:
- A new Recommendation on the characterizations and specifications of the
power feeding system, especially for the Higher Voltage DC system.
- A new Recommendation on safety for humans and equipment of the power
- A new Recommendation on the system configuration, architecture, and
cable distribution including feeding, lightning protection, EMC, earthing,
and bonding of the power feeding system.
- A new recommendation on methodologies for evaluating the performance of
energy feeding and its environmental impact.
- 1, 4, 6, 8, 11, 12, 14, 17, and 18/5
- ITU-T SGs 9, 13, 15, and 16