Exploring Data Center PDUs: Floor PDUs vs. Rack and Cabinet PDUs

A highly reliable power source is essential to data center operations. However, the layout of the modern data center, with rows of racks and cabinets, makes it difficult to supply power to IT equipment. The power distribution unit (PDU) is designed to solve this problem.

What Is a PDU in the Data Center?

As the name implies, the job of a PDU is to distribute electricity throughout the data center. It takes AC or DC power from the source — be that the electric utility, a generator, or an uninterruptible power supply (UPS) — and delivers it to IT equipment. The PDU can supply AC or DC power and may have various types of receptacles to support different equipment plugs.

PDUs help ensure that the right amount of power capacity is available in the right place to support the demands of the IT infrastructure. They minimize the distance between the IT equipment and an available outlet to enhance power quality and simplify cable management. Organizations also use network-connected “smart” PDUs to monitor and manage power usage and availability. More on smart vs. basic PDUs and metered vs. switched PDUs.

See our blogs about “What is a PDU?” and “How does a PDU work?” for a thorough overview of the basics.

Two Types of Data Center PDUs

The data center has two main types of PDUs: floor PDUs and rack/cabinet PDUs (also known as “rack PDUs” or “rackmount PDUs”). When most people think of PDUs, they think of the rack/cabinet variety. However, floor PDUs are also useful in data centers with large numbers of racks and cabinets, working in conjunction with rackmount PDUs to streamline power delivery.

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PDUs for Racks and Cabinets

Depending on the form factor, PDUs for racks and cabinets are installed horizontally in the equipment mounting area or vertically in the back of the unit (vertical PDUs vs. horizontal PDUs). Horizontal PDUs are typically 1U or 2U in height and have eight to 16 outlets. Vertically mounted PDUs are 0U units that don’t use any of the available space for IT equipment and have up to 60 outlets depending on the height of the cabinet.

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 can be configured to meet specific needs. Explore the different types of server rack PDUs.

Floor-Mounted PDUs

Floor-mounted or cabinet-based PDUs can supply 300kVA or more. Larger and more expensive than rackmount PDUs, they sit by themselves on the data center floor and transform one or more power supplies into multiple lower-capacity power supplies. Those that support high voltages typically have compartmentalized designs that isolate the controls for safety.

They fall into three primary categories with one additional related tool:

Power Distribution Cabinets

These cabinets contain large PDUs used to supply power to multiple racks and cabinets in a large data center. They provide branch circuit monitoring and power conditioning and generally have monitoring capabilities.

Power Distribution Racks (PDRs)

These are more compact, space-saving units used to accommodate growing power loads in high-density data centers. They provide up to 168 circuits to support multiple rackmount PDUs.

Remote Power Panels (RPPs)

These units provide up to 168 circuits using power feeds from existing panelboards or transformers. They enable electrical expansion without expensive rework and have a highly compact design with extensive monitoring capabilities.

Overhead Busways

High-density data centers also use overhead busways for power distribution. These solutions don’t take up floor space and allow greater flexibility and scalability. Think of these as cabling highways within the data center.

What to Look for in a Data Center PDU

As power densities increase, effective power distribution becomes more critical. PDUs play a strategic role in the data center infrastructure and should be chosen carefully based on quality and performance. Data center operators should evaluate the power demands of the data center and ensure that they have enough PDU capacity to accommodate anticipated growth. Learn how to choose the best server rack and data center PDUs.

The power experts at Enconnex are here to help you select the right power distribution units for each use case. Our PDU line is growing. We are preparing to launch new TAA-compliant, made-in-America basic PDUs soon. View our catalog to see all our PDUs for sale, and contact us to get the right PDU for your use case and to stay up to date on our latest offerings.

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Posted by Robert Faulkner on December 14, 2022

Robert Faulkner is the Vice President of Engineering and Operations at Enconnex. He comes from a strong background in product management with over 20 years in the IT industry. He currently holds an MSME and CDCD certification. He earned his MS degree in Mechanical Engineering at University of Nevada, Reno.

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