DC Power Could Be Headed to Your Data Center

As power densities increase, co-location and hyperscale data center operators need to take advantage of every opportunity to reduce power consumption. Is it possible that 380V direct current (DC) might be the solution?

To answer that question, it’s important to understand the history behind AC (alternating current) and DC power, the pros and cons of using DC power in data centers, and the potential future of DC power.

Some History: AC vs. DC

The world might be different if Thomas Edison had won the power war back in the 1800s. In addition to inventing the light bulb, Edison was the inventor and patent holder of an electrical distribution system based on direct electric current. He opened the first electric utility company in New York in 1882 to supply electricity to 59 customers. By the late 1890s, he had constructed and was operating 100+ direct electric power plants in the Northeast.  

His push to deploy DC power plants ended after one of his employees (Nikola Tesla) joined George Westinghouse; together, they developed an AC power distribution system. The AC power plant was much more efficient than Edison's DC plant; AC power plants could distribute power to customers over hundreds of miles compared to DC power plants that needed to be placed within a few miles of homes and offices. 

Today’s industrial world uses power based on alternating current; however, there is a movement toward 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 centers.

Differences Between AC and DC

Direct current is linear; alternating current "alternates." Batteries, solar photovoltaic panels, wind turbines and fuel cells produce direct current. The current always flows in the same direction, and does not oscillate between positive and negative terminals.

Alternating current, however, reverses 60 times per second (U.S.) or 50 times per second (Europe), and the voltage is easily transformed. This makes it easy to transport over several miles as compared to DC power plants. 

Courtesy of DC-NEXUS

Telecommunications Systems and DC Power

Telecommunications companies have used DC power solutions for decades. Today, every telco central office houses a 48V DC plant that provides DC power to telecommunications IT equipment and a very reliable three- to eight-hour battery plant.

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.

Deploying DC Power Solutions in Data Centers

Modern data centers typically rely on traditional AC voltage to DC voltages at the server (i.e. utility power --> primary/secondary power distribution systems --> uninterruptible power supply [UPS] --> power distribution unit [PDU] --> server).

As you can see, there are several changes in state, resulting in wasted energy (rejected as heat) that must be cooled; the final power transformation occurs from AC --> DC power within the server.

The 380V DC system incorporates a single conversion from a 480V grid provided alternating current to a 380V direct current power supply native within the server, which then converts the higher voltage to a lower voltage (12V DC).

Typical data center AC power supply showing AC/DC conversions that would be removed using a 380V DC solution to increase efficiency and system resiliency. Courtesy of DC-NEXUS.

380V DC data center power technology, which has been developed by large technology firms like NTT Energy and ABB Group, provides simpler, more efficient and cost-effective solutions as compared to traditional AC power supply solutions.

Knowledge-based online news outlets, such as DC-NEXUS, and product development associations, such as EMerge Alliance, offer end-users helpful information about design, integration firm partners and technical resources for developing 380V DC solutions. DC-NEXUS, for example, issues a weekly newsletter that covers DC technology and its use in several markets, including data centers.

Pros and Cons of 380V DC Power

There are several advantages of using a 380V DC power solution to power critical data center equipment instead of AC power, including:

• Increased reliability
• Fewer conversions
• Smaller bus and copper sizes can be used
• Distributed energy storage can be used in DC systems
• Simpler design and implementation
• Lower upfront costs
• Lower operating costs
• Lower system maintenance costs
• Fewer physical space requirements, providing more server area white space
• 380V DC microgrids can be developed
• More efficient 380V DC motors and controls can be used
• Improved efficiency of between 8% and 10%

Despite the long list of advantages, there are some drawbacks to consider when using a 380V DC power solution:

• Lack of availability of components
• Lack of support from mainstream technology hardware vendors
• Overall lack of industry design, construction and operations experience
• Safety concerns
• Holistic planning is necessary from the primary power grid to the computer server
  
  

Is DC Power Right for Your Data Center?

DC power solutions are just one way that data center owners/operators can save money and energy. With careful planning and design, and working with the right partner, your data center can take advantage of the benefits that DC power has to offer.

Belden has the expertise to help you determine whether DC power may be an option in your existing data center or in a future data center project. If you decide to pursue it, our solutions can support it. Contact us to learn more!