The Electrical Backbone ⚡️: PDUs, Busways, and How They Distribute Power in Your Data Center

In a modern data center, with its rows of racks and cabinets, delivering power to all IT equipment is a challenge. This is where the Power Distribution Unit (PDU) comes in.Its job is to distribute electricity from the source, whether the grid, a generator, or a UPS, to the IT equipment.

There are two main types of PDUs in the data center:

• Rack and Cabinet PDUs (Rackmount PDUs): Think of them as smart “power strips” for servers. They are installed horizontally or vertically in racks and can have up to 60 outlets, depending on the cabinet height. Advanced units offer per-outlet power monitoring and remote management. Larger PDUs may have color-coded sections that coordinate outlets with circuit breakers to prevent unbalanced loads. Locking features reduce the risk of accidental disconnections.

• Floor-Mounted PDUs (Floor PDUs): They are larger units, often the size of a rack or more, located on the data center floor. They transform one or more high-capacity power sources into multiple lower-capacity supplies to power several rows of racks. They may include transformers and switch panels.

In addition to PDUs, high-density data centers are adopting an innovative alternative to traditional cables for power distribution: busway systems..

• Traditionally, cable has been the main carrier for electrical power distribution. However, as demand in data centers has grown (up to 5000A and beyond!), busway has proven to be a very cost-effective and viable alternative to cable for high-current applications. In fact, in many data centers, busway has already replaced cable for these high-current connections.

• A full critical power distribution design based on busway can significantly reduce capital expenditures (CapEx) when implemented across the entire distribution system.

• Beyond costs, busway offers greater configuration flexibility, “pay-as-you-grow” options, and minimal maintenance. In fact, using busway can be nearly 60% more cost-effective than cable for the same system and can free up about 8% of data center space by eliminating the need for traditional PDU systems in the data hall.

Finalmente, para asegurar la máxima confiabilidad, la discriminación de interruptores automáticos (selectividad) es crucial. Esto significa que, ante una falla, el interruptor más cercano al problema debe dispararse primero, limitando la interrupción del servicio a la mínima cantidad posible. Esto aplica desde un fallo en un suministro de rack hasta un problema en una PDU, asegurando que solo se vea afectada la porción mínima necesaria del sistema. ¡Un diseño bien pensado es la clave para la continuidad! 🛠️

Sources: “Bus Way vs. Cable: a CapEx comparison – Amazon S3”, “Exploring Data Center PDUs: Floor PDUs vs. Rack & Cabinet PDUs – BLOG – Enconnex”, “Circuit Breaker Discrimination for Reliable Data Centre – Future-tech”, “The Basics of Electrical Data Center Design in 2025 – gbc engineers”, “can anyone help me understand PDUs with in a large Data Center? : r/datacenter – Reddit”