Why make the switch to DC power?


Socomec’s Jean–Yves Chaboute argues that data centres can improve effiency by moving to DC distribution

As power densities increase, colocation and hyperscale data centre operators need to maximise every opportunity to reduce power consumption – and associated costs. One such opportunity is to use energy saving 380V direct current (DC), which could be a game changer for the entire data centre industry. 

Today, the industrial world uses power based on alternating current; there is, however, a movement towards using DC power sources in a wide variety of applications, including sustainable power (photovoltaics, wind and fuel cells), microgrids (residential and small commercial) and data centres. 

Telecommunications systems and DC Power 

Already proven within the telecommunications sector, telco companies have successfully used DC power solutions for decades. Historically, exchanges have operated on -48VDC for reasons of safety, durability (lack of cathodic corrosion), fault tracing and easy battery integration. However, some facilities are now moving to a higher DC voltage for new data centres. 

A driving force behind innovation and learning in this sector – and helping to deliver learnings to wider industry – is the Open Compute Project (OCP). Created as a collaborative community to support the growing demands on compute infrastructure, the OCP is an organisation that shares designs of data centre products among companies including Facebook, IBM, Intel, Nokia, Google, Microsoft, Seagate Technology, Dell, Rackspace, Cisco, Goldman Sachs, Fidelity, Lenovo and Alibaba Group. 

When Facebook found it was outgrowing its traditional infrastructure in 2009, the business initiated a project to design the world’s most energy efficient data centre. In 2011, Facebook shared these designs and launched the OCP in conjunction with Intel, Rackspace, Goldman Sachs and Andy Bechtolsheim. 

The mission of the group is to spur rapid innovation across a global community, sharing intellectual property in order to encourage the IT industry to evolve. The Open Compute Summit recently started a group dedicated to telecommunications technology firms that deploy DC solutions. In 2016, Google announced development of a 48V rack solution, and is working with Facebook and others to further the development of a DC solution within the Open Compute environment. 

The IBM supercomputer, used by the MET office, is an example where DC distribution has already been tried and tested. This application is currently being supplied with 520Vdc. While the vast majority of data centres in the UK currently use AC distribution, DC distribution can bring advantages to any type of data centre by reducing the number of stages in the electrical system. In short, DC/DC conversion is simpler than multiple AC/DC and DC/AC conversion stages.

Modern data centres typically rely on traditional AC voltage to DC voltages at the server (ie utility power –> primary/secondary power distribution systems –> uninterruptible power supply [UPS] –> power distribution unit [PDU] –> server). Each conversion causes losses in an environment where efficiency is key. 

Colocation is a likely candidate for DC distribution, due to the intense competition for efficiency, while the benefit for edge data centres would be for remote sites where all or part of the energy supply is from renewables (solar) and battery storage is employed. Typically this would be telecom applications or containerised data centres.

Pros of 380V DC power 

Clearly, the success of DC solutions within the telecommunications industry can bring highly transferrable advantages to every sector – whether creating a new facility or upgrading existing infrastructure with a simple retrofit. 

When deploying a 380VDC solution to power critical data centre equipment instead of AC power, efficiency has been proven to increase between 8% and 10%, with more efficient 380VDC motors and controls being used. With increased reliability and fewer conversions, both upfront expenditure and operating costs are lower. Furthermore, with a simpler design and implementation, system maintenance costs are reduced. Physical space requirements are less – with smaller bus and copper sizes being used – so more server area white space is available. Distributed energy storage can be used in DC systems and 380V DC microgrids can be developed. 

Is DC power right for your data centre? 

DC power solutions are just one way that data centre owners and operators can save money and energy. With careful planning and design, and working with the right partner, every data centre can benefit from the unique advantages that DC power has to offer. 

Able to monitor not only energy consumption, the higher end voltage and current modules can also monitor power quality events and max demand – enabling better, more informed decision making. 

Furthermore, the accuracy of measurements is guaranteed according to IEC 61557-12; class 0.5 from 2% to 120% of the nominal current on the global chain when associated with the Digiware sensors. 

Digiware centralises measurements for the main incoming circuit, all sub feeds and branch-circuits locally then communicates them to DCIM / EMS / SCADA / BMS software solutions over multiple open protocols (MODBUS, SNMP and BAC net). 

By delivering a compact and powerful solution to track power usage – for both main and individual circuits – Diris Digiware is ideal for any current rating, for a large number of circuits and for new or existing installations using solid core or split-core current sensors. 

Thanks to the system’s voltage adaptors, Diris Digiware is suitable for both telecoms sites (-48VDC) and more recent data centre and electrical infrastructures operating at higher voltages such as 380VDC. 

The future

DC distribution is now becoming a reality and this will lead to a simplification of data centre architecture, as well as reducing risk. As always the end-user gains need to be quantified before DC distribution can be widely deployed and operations staff will need familiarising with the new equipment and architecture.

In the next five years, we will see some trial projects in universities, but also in industry, as well as some developments for remote edge data centres. As there is increasing adoption of this approach, operators will require DC monitoring solutions to validate the benefits of DC architecture; not only for efficiency but also for power quality, and Socomec’s solutions are ready for this.


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