What is a Power Distribution Unit (PDU)? - Definition and examples

A PDU, or Power Distribution Unit, is a device used to control and distribute electric power. The most basic form of a PDU is a large power strip without surge protection. This is designed to provide standard electrical outlets for use within a variety of settings that don't require monitoring or remote access capabilities.

For larger projects, a floor-mounted PDU, sometimes referred to as a Main Distribution Unit, provides a crucial management bridge that connects the building's primary power source and a variety of equipment racks within a data center or remote location. These units can handle considerably larger amounts of energy as well as the ability to support the load required by multiple racks of gear.

A rack-mounted PDU mounts directly into the equipment rack so it can monitor and control the power supply to specific servers, switches, and other data center devices and assist in balancing power loads. These PDUs can be described by several different names including 'Smart' or Intelligent PDUs.

"PDU" Definition

The acronym "PDU" stands for Power Distribution Unit. PDUs are, essentially, industrial-grade power strips used (in most cases) to power servers and telecommunications equipment.

You'll generally have too many devices at a site to plug them all directly into your power supply. You need PDUs to distribute your site's power to each device. This is possible because a PDU turns one (or a few) power inputs into many (usually about eight) power outputs.

PDUs are available in both AC and DC models to match the power in use at different kinds of sites.

DC PDUs are built just like their AC-power counterparts, except for their output current.

DC power distribution units are designed to provide electric current in the Direct Current format that many rack-mounted devices use.

"Rack PDU" Definition

Now let's add another layer to our definition by adding the word "rack". A "rack PDU" is a PDU that is designed to be mounted in an industry-standard equipment rack. These are typically either 19 inches or 23 inches in width. Height can vary from PDU to PDU, but most are just one "rack unit" high. This translates to about 1.75 inches.

A rack PDU is different from other kinds of PDUs that are designed to be wall-mounted or attached to the side of an equipment rack. These other PDUs conserve valuable physical rack space in cramped equipment racks, but they do increase the distance between the power outputs of the PDU and the power inputs of the devices that will receive electricity.

Switched Rack PDU example: Remote Power Controller 100
This is one example of a switched rack PDU, the Remote Power Controller 100 from DPS Telecom.

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