Higher-Voltage AC as a Power Savings Tool

emerson-switchgear

Staff from Emerson Network Power staff check out the power switchgear at its new data center in St. Louis.

Data center professionals continue to debate the merits of AC vs. DC for distributing power throughout a data center. A related topic that has received less attention is the potential for alternate approaches to AC power distribution.

Emerson Network Power expects to reduce the power bill for its new data center in St. Louis by 1 percent by using slightly higher voltage for the facility's power distribution. Emerson is using 240 volt AC power instead of the traditional 208 volt.

Jack Pouchet, Director of Energy Initiatives at Emerson Network Power, says most data center equipment will work in a range from 100 to 260 volts. "You don't need to go to DC or make other radical changes to get improvements," said Pouchet.

Some customers are reluctant to consider alternate AC designs, citing potential problems with contractors and others who would support the systems. Pouchet said he believes this is overblown, and that 240 volt and other voltages would be well supported.

Emerson is not alone in recommending alternate AC voltages. Another long-time proponent is Neil Rasmussen of APC by Schneider, who has written a white paper (PDF) supporting the 230 volt standard used in Europe. The Green Grid has also issued several white papers on power configuration options that examined the merits and drawbacks of multiple AC and DC configurations (see papers offering both qualitative and quantative efficiency analyses).