Power Distribution Units

A rack PDU (power distribution unit) is a device designed to fit into a server rack in either a vertical (0U) or horizontal (1U or more) position. Rack mount PDUs are offered in many sizes and configurations depending on voltage, current, number, and type of connections, as well as remote access and monitoring functionality.

A PDUs main purpose is to supply AC power to multiple pieces of IT equipment within the rack. This can be as simple as a basic power strip with no internal intelligence that simply provides AC power to the connected IT equipment, or as advanced as an outlet-level PDU that can remotely monitor, control, and report on the status of every outlet within the unit.


  • Basic – Provide power to the IT equipment without any advanced features such as metering or monitoring. They are widely available, easy to use and have a lower cost.
  • Metered – Provide the data necessary to properly load and balance rack power circuits. LED display lets administrators know how much headroom exists between current capacity and the maximum draw of the strip.
  • Smart/Monitored – Typically include the feature sets of metered products in a single unit but also has the ability to remotely (IP) monitor the state of the distribution unit.
  • Switched – Includes the features of the Metered PDU as well as the ability to remotely control the on/off state and reboot capabilities of each outlet contained in the unit through a web interface or a serial (RS232) menu.
  • Outlet Level Power Monitoring – Provides unprecedented reliable and granular visibility into power consumption, coupled with remote/network power, and environmental monitoring.

Rack PDU

Uninterruptible Power Supply

UPS (Uninterruptible Power Supply) is a back-up power system used to ensure uninterrupted power for various electronic devices. All but the most basic UPS systems also condition incoming power to level out sags and surges, helping to prevent damage to today’s sensitive electronic gear.

A UPS has it’s own rechargeable battery which provides emergency power for your system immediately when the main supply is cut, therefore preventing data loss. In the event of a sustained power failure, the UPS will provide sufficient battery power for your files to be saved and for the whole system to be shut down in an orderly manner. If an alternative power source such as a generator is available, the battery will provide sufficient power to keep your system running until the secondary supply is brought online. Most UPS’s also filter the power supply entering your computer system, limiting the detrimental effect of “spikes”, “noise” and other electrical disturbances.


  • Single-Conversion Systems – More efficient than double-conversion devices, but offer less protection. A good fit for loads with a higher tolerance for failure. The UPS stays on battery power until the AC input returns to normal tolerances or the battery runs out of power, whichever happens first. Two of the most popular single-conversion designs are standby and line-interactive:
  • Standby Power System (SPS) – Most commonly used to protect POS equipment and single work stations. Standby UPSs allow IT equipment to run off utility power until the UPS detects a problem, at which point it switches to battery power.
  • Line Interactive – Most commonly used UPS system for network environments. Used for small networks all the way up to enterprise applications. These UPS systems regulate input voltage up or down as necessary before allowing it to pass through to protected equipment.
  • Double Conversion On-line UPS – Less efficient, but provides the highest levels of protection and are usually the standard choice for protecting mission-critical systems. The double-conversion process isolates critical loads from raw utility power completely, ensuring that IT equipment receives only clean, reliable electricity. In normal operation, a double-conversion UPS continually processes power twice.
  • Multi-Mode Systems – Although they may be more expensive than either single or double conversion systems, they are the best choice for companies looking to achieve an optimal blend of both efficiency and protection. These combine features of both single- and double-conversion technologies and provide substantial improvements in both efficiency and reliability.

Read 5 Key Considerations when choosing your next PDU