Power Distribution Unit (PDU) Basics

A power distribution unit, also known as a PDU, is a device designed to distribute electric power through multiple outlets. These pieces of equipment come in several forms but all serve the same basic function.

The term PDU can be linked to two major styles of hardware power devices.

  • 1. Larger, higher-cost floor-mounted units designed to transform one or more raw power feeds into any number of lower capacity distributed power feeds. These units are typically found in a data center located by themselves and sending power out to a large number of equipment racks.
  • 2. Smaller devices fitted with multiple appliance outlets designed to provide power to units within a rack. This type of power distribution unit can also come with various functions such as a monitoring and remote control features allowing technicians to keep an eye on their power supply.

Some PDUs provide remote access. Common methods include a RS-232 serial connection or a LAN network-controller accessible through monitored protocols, SNMP, or a web page. This allows an administrator to access the PDU from a remote terminal and interface with it to turn outlets on or off, to schedule power shutdowns, to control load, etc. This can be helpful if a remote machine has gone into an unresponsive state and will not restart through normal means. An administrator can connect to the PDU the machine is plugged into to power-cycle the machine.

One of the challenges in selecting PDUs for a data-center application is to balance the cost of the rack-PDU in the context of an organization's energy-management goals. Inexpensive rack-PDUs may distribute power effectively, but they offer little if any understanding or control of that energy flow. With energy costs rising over the past several years (circa 2010), IT professionals have begun to take a more comprehensive view of power management with rack-PDUs with more intelligence. The trend is more intelligence and higher-quality rack-PDU devices