Green’s Zurich-West leads the way for DC

The world’s data centres demand around 80 million MWh of electricity per year, which equates to 2 percent of total CO2 emissions and demand is growing. An extra 5.75 million new servers are added to the ranks every year, causing demand to grow by 10 percent.

To balance the financial and environment costs of growing demand, operators are keen to improve the efficiency of their data centres. One major opportunity is in eliminating the energy lost when converting AC (alternating current) to DC (direct current) and back.

While the grid carries AC power to the door, electronic equipment works from DC, as do the batteries in UPS systems. By switching to a DC power system, data centre operators can convert from AC to DC only once, simplifying their power supply and removing the need for equipment, as well as saving the energy that is lost during conversion.
Because less equipment needs to be purchased, installed and maintained, investment costs are 15 percent lower and the footprint is 25 percent smaller than a comparable AC system. Fewer components lead to fewer outages, improved reliability and lower operating and maintenance costs in a sector where outages can cost upwards of $1 million per hour.

World’s largest DC data centre

The world’s largest DC-powered data centre opened its doors in May 2012 in Switzerland following a project between operator Green, and partners ABB and HP. The Green group is a major Swiss data centre operator employed by banks, insurance companies, system integrators and technology companies around the world.
Its stringent ecological values meant that it jumped at the opportunity for ABB to deliver the pilot project, which had the goal of operating the data centre with greater efficiency and consuming less energy than a conventionally powered centre.
ABB’s installation is a fully redundant one megawatt DC power distribution solution for a 1,100 m2 expansion of the 3,300 m2 Zurich-West data centre and meets the specifications of the International Electrotechnical Commission (IEC). The project won the prestigious Swiss Federal Office of Energy’s Watt d’Or prize for buildings and space in 2013.
Performance tests have shown that the data centre’s power distribution system is 10 percent more efficient than comparable AC technology and investment costs were 15 percent lower.
Franz Grueter, CEO of Green said: “The implementation of 380 volt DC technology in our data centre is part of our long-term energy optimisation strategy, a big step that has set a new standard in the industry. When fully loaded, the system will result in energy savings of up to 20 percent in power consumption from grid to chip and in cooling.”

DC power distribution

The system was installed by ABB Switzerland in collaboration with Validus DC systems,
a leading supplier of DC power infrastructure and is powered by AC power from the local grid at 16 kV or an emergency power system. These feed into ABB’s ZS medium voltage GIS (gas-insulated switchgear).
Power is then converted into 400 V DC by a rectifier unit made up of a medium-voltage switch, a highly efficient transformer and a rectifier unit based on high efficiency power electronics and semiconductors.
DC power is then distributed to servers throughout Green’s facility with no need for further transformation to power equipment or to connect with the site’s battery system, which is based on DC power and which stores energy to power the site for 10 minutes while the emergency power system is brought online.

AC comparison

From the point of the medium-voltage GIS, a comparable AC power supply would include medium-voltage transformers, AC switchgear, power conversion equipment for the UPS, AC power distribution units and AC power supply units for every item of equipment in the data centre.
Switching to DC will not only cut the costs of power engineering equipment but will also save costs in installation, operation and maintenance and will free up valuable space for servers. Plus, by removing the individual power supply units for every item of equipment, the operator will not only improve energy efficiency but will also reduce the need for cooling in the IT room (and the energy demands of the cooling equipment).

Decathlon for Data Centres

Green is also making use of Decathlon for Data Centres, ABB’s data centre infrastructure management (DCIM) solution, at Zurich West. The software delivers precise monitoring, control and automation of the building management and electrical power systems and is Green’s primary data centre automation solution. As part of the package, ABB has deployed its Decathlon Command Centre Extended Operator Workplace solution, which enables operators to oversee and manage the entire operation.

Reliability and efficiency

Tarak Mehta, head of ABB’s Low Voltage Products division said: “Across all our business areas, customers are asking for improved availability and energy efficiency, and DC power is an effective solution. Zurich West will serve as a global showcase to demonstrate that DC is a complementary technology in data centres as it enhances reliability while minimising footprint, installation and maintenance costs.”

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