|“It’s like Tesla versus Edison all over again. Alternating current (AC) is king today, but when it comes to finding ways to improve data center energy efficiency, some industry experts say direct current (DC) deserves a second look.” — Alex Barrett|
Today’s WhatIs.com Word of the Day is dirty electricity — also known as electrical pollution.
Electricity comes from the utility in alternating current (AC). AC is the form in which power is more easily distributed. AC is converted to DC at the power distribution unit, then converted to AC again to push out to the servers, and is converted one more time to DC at each individual server.
In a DC power distribution system, there is only one conversion from the main building AC to DC at common power supply for multiple pieces of equipment. The DC power is fed directly to the servers and switches, and also keeps the batteries charged. This has been the approach in the telco industry for decades on high-end PBX equipment.
DC-powered servers don’t have power supplies built in. The power supply is in the infrastructure. Taking the power supplies out of the equipment itself and putting it in the rack reduces space and takes away the need for an extra conversion.