Power distribution units (PDUs) are an essential part of the IT infrastructure. Without them, there would be no real way to plug in IT equipment! As the name implies, PDUs bring electricity from a utility power source, generator, or uninterruptible power supply (UPS) to the racks and cabinets distributed throughout the data center. They use electrical current from one source to power multiple devices.
Beyond that basic definition, PDUs vary widely in terms of features and functionality. We’ll list a few common types of configuration options below:
- Some PDUs are designed to mount horizontally in a rack, while others mount vertically in the “zero U” space of the enclosure (vertical vs. horizontal PDU overview).
- There are specific PDUs for single-phase and three-phase power sources and different voltages (single vs. three-phase PDU overview).
- “Smart” PDUs (also known as “intelligent” PDUs) connect to the network to enable remote monitoring of input and output voltage, amperage, kilowatts consumed, and other information (intelligent vs. basic PDU overview).
- Metered PDUs measure the amperage to prevent overloading. This can be done at an individual outlet level or collectively. Switched PDUs allow administrators to control outlets collectively or individually (switched vs. metered PDU overview)
PDUs also have different types of plugs, receptacles, and power cords to meet various requirements. A basic understanding of these components is essential to selecting the right PDU for your environment.
PDU Plug or Input Connector Types
One of the first things to determine when choosing a PDU is what PDU connector or plug types your configuration calls for. Input connectors, or plugs, attach the PDU to the input power source. In essence, the PDU plug needs to match the receptacle. The International Electrotechnical Commission (IEC) and National Electrical Manufacturers Association (NEMA) have established standards for plug and receptacle types, which are designated by codes.
- IEC 60320 are some of the most commonly used connectors. These include the C13, C14, C19, and C20 plugs.
- IEC 60309 connectors are used in industrial environments. They are designated by the configuration of pole (P), earth/ground (E) and neutral pins – for example, 2P+E, 3P+E and 3P+N+E. Yellow fittings are generally for 100V to 130V, blue for 200V to 250V, and red for 380V to 480V.
- NEMA connectors are designated by P for plug and R for receptacle (socket). Common types of plugs are 5-15P and 5-20P, L5-20P and L5-30P, L6-20P and L6-30P, L15-20P and L15-30P, and L21-20P and L-30P. The L indicates a locking plug.
- A Hubbell CS8365C plug is a proprietary locking connector manufactured by Hubbell, Inc.
The choice of PDU plug – and the PDU itself – also depends upon whether the power is single-phase or three-phase. Most office buildings use single-phase power, while larger data centers and industrial facilities use three-phase power.
PDU Receptacle or Outlet Types
Choosing the right PDU outlet or receptacle types is also an important consideration when choosing a PDU. It’s often necessary to power both 120V IT devices as well as more demanding servers. As a result, many PDUs have multiple NEMA 5-15R and 5-20R receptacles. Some have combinations of NEMA L5-30R and L6-30R and IEC 60320 receptacles. Before ordering a PDU, you should determine the type and number of plugs of the equipment in the rack and configure the PDU accordingly. It’s good to have extra receptacles for expansion, as long as the PDU isn’t overloaded.
More On PDU Power Cord Types
The last piece of the PDU puzzle is PDU power cord size. Input PDU power cords (also known as PDU whips) typically range from 10 to 15 feet and have a heavy-duty construction for safety and durability. Output PDU power cords (also known as jumper cords) lengths can vary from 1 to 15 feet. The most important thing to consider when choosing both input and output PDU power cords (outside of plug types) is the amperage and voltage they support. Input cables need to sufficiently handle the power generated from the main power source and the output cables need to support the power draw coming from each individual device to maintain efficient performance and safety.
The diameter of the power cord determines the amperage it supports. In the United States, diameter is commonly measured in terms of American Wire Gauge (AWG). Internationally, diameter is measured in square millimeters (mm2). With AWG, the lower the number, the thicker the cord is and the higher the amperage it supports. For example, three-phase power cords are thicker and heavier than single-phase cords. Input PDU power cords (PDU whips) typically range from 10-4 AWG and output PDU power cords (jumper cords) typically range from 18-14 AWG.
Enconnex Power Distribution Units
Enconnex offers a full line of power distribution units available in a wide range of configurations. Designed for performance and scalability, our PDUs integrate seamlessly into your environment. Combine them with other Enconnex solutions to save time, reduce costs, and improve overall network performance.
Contact Enconnex today to learn more.