What Is a Power Distribution Unit (PDU) and What Does It Do?

Power is a foundational element of data center operations. Without a highly reliable power source, data center operators cannot ensure the availability and performance of IT systems. That’s why the power distribution unit (PDU) is one of the most important components of the data center infrastructure.

What Is a PDU?

PDU stands for “power distribution unit.” A PDU is essentially a large power strip with multiple electrical outlets for plugging in IT equipment. PDUs have up to 60 outlets — far more outlets than a power strip — and can support a much greater power load. They are used in the data center to distribute power efficiently across all the racks, cabinets, and technology within. In another blog, we explore the differences between PDUs vs. power strips. 

PDUs are available in numerous configurations. Some can be mounted to a wall or the outside of a rack, but the most popular versions mount within the rack or cabinet. These are known as rack mount PDUs. They minimize the distance between the IT equipment and the available outlets. Rack mount PDUs come in a variety of form factors, from 1U and 2U units that fit in the equipment-mounting area to 0U units that mount vertically in the back of a cabinet.

What Does a PDU Do?

The job of a PDU is to bring power from a primary electrical source into the data center. Floor-mounted PDUs, also known as main distribution units, can supply 300kVA or more to power multiple racks and cabinets. Standard-density rack mount PDUs are generally rated up to 5kW, and high-density PDUs up to 10kW. There are also ultra-high-density PDUs for even greater power loads.

A rack mount PDU can supply AC or DC power and may have various types of receptacles to support different equipment plugs. Larger PDUs have color-coded sections that coordinate outlets with a circuit breaker to prevent unbalanced loading. Locking features reduce the risk of accidental disconnects. Best-in-class units are configurable to meet specific needs. See our blog on PDU power cord types for more information.

Choosing a PDU

It’s important to evaluate the specifications of the PDU against the power requirements of the equipment in the rack or cabinet before making a purchase. Key considerations include:

• Does the data center supply AC or DC power? What voltage is used — 120V, 240V, or 330V? And, 1-phase or 3-phase?
• What is the total power load of the equipment connecting to the PDU?\
• What types of outlets are needed to support the various pieces of equipment?
• How many outlets are needed, keeping in mind future needs?
• How will the PDU be installed — horizontally in the equipment-mounting area or vertically in the back of the rack?

Check out our PDU buying guide for more information about choosing the best PDU.

Other Features to Look For

A PDU is not a commodity product. Because it’s a mission-critical component of the data center infrastructure, it’s important to look for high-quality PDUs that will provide trouble-free service. You will also need to consider whether you could benefit from an intelligent PDU that connects to the network for remote monitoring and management.

Intelligent PDUs fall into two broad categories:

• Metered PDUs capture a variety of metrics — including current, voltage, actual and apparent power usage, and more — at the input or outlet level. Metered PDUs help technicians make better deployment decisions, avoid overloading circuits and optimize energy use.
• Switched PDUs provide precision control of devices for advanced power management and reduced risk. Technicians can power on, off, and reboot individual outlets to power cycle individual devices, enable power sequencing delays and prevent the unauthorized installation of devices on unused outlets.

Some intelligent PDUs also support add-on features such as environmental monitoring sensors that measure temperature, humidity, and airflow and detect smoke, water, or vibrations.

High-Quality Rack Mount PDUs from Enconnex

Enconnex offers a comprehensive line of rack mount PDUs to meet a wide range of specifications. We are getting ready to launch a new line of TAA-compliant, made-in-America basic PDUs as well. Contact our power specialists to get the right PDU for your use case and to stay up to date on our latest offerings.